w3 Dev BLOG - Share the knowledge .NET

Windows 7: How to access password protected shared folder

2011-11-01T08:19:00.000-07:00

How to pass current Windows credentials to password protected network share

1. Create user/password on destination computer matching the user/password of current computer
2. Share a folder on the destination computer giving access to the new created user
3. On current computer change the local security settings as following:
3.1 Open Local Security Policy Console
3.2 Select Local policies -> Security Options -> Network security: LAN Manager authentication level
3.3 Select Send LM and NTLM response and click OK.

You can also specify different user to connect by during mapping a network drive on the destination computer.

IIS Redirection with Page and Query String

2011-07-14T08:42:00.000-07:00

By default IIS redirects to a given domain and/or application.
The web page and query string can be transferred to the destination url by using the respective parameters $S and $Q.

Ex.
template: http://example.com$S$Q
redirection from
http://old-example.com/default.aspx?id=1
will lead to
http://example.com/default.aspx?id=1

In IIS 6 the checkbox "Exact Url" will avoid appending the web page to the query string.

How to concatenate row data into string using SQL

2011-04-22T08:53:00.000-07:00

Very simple way to achieve this is to use FOR XML statement. The result of the following example is list of user names including first and last name separated by commas.

SELECT FirstName+' '+LastName+', ' FROM UserProfile FOR XML PATH('')

But the result string ends with a comma and space. We can either remove it by SUBSTR or REPLACE functions. Using REPLACE as it is shown below saves the usage of subquery or calcualtion of the length of the same expression.

SELECT
REPLACE((REPLACE((REPLACE(
(SELECT FirstName+' '+LastName FROM UserProfile FOR XML PATH('A'))
,'</A><A>',', '))
, '</A>',''))
,'<A>','')

Here is another way to achieve this which might be convinient in stored procedures.

DECLARE @Names VARCHAR(8000)
set @Names=''
SELECT @Names = @Names + CASE WHEN @Names<>''
THEN ', ' ELSE '' END + Name
FROM Users
SELECT @Names

Solution on "HTTP Error 414 Request URI too long" error using getJSON

2011-01-23T08:44:00.000-08:00

The explanation of 414 error is described here:
http://support.microsoft.com/kb/248061

With regard to JSON queries with jQuery this basically means we are not able to use long GET parameters. But for sure this is necessary for sending bigger objects serialized as JSON.
The solution would be using POST requests, but is jQuery support that?

The answer is yes if we just extend jQuery with post requests as it is described in jQuery forum:
http://forum.jquery.com/topic/getjson-using-post

jQuery.extend({
postJSON: function( url, data, callback) {
return jQuery.post(url, data, callback, "json");
}
});

Then just replace getJSON with postJSON where it is needed.

IIS Url Rewriting - avoid repeat of querystring parameters

2010-12-29T03:07:00.000-08:00

Using the URL rewriting mechanism of IIS causes repeat of querystring parameters on every postback, because it builds the postaback url (rewrites url) by appending the querystring to current url.

Actual url:

/product.aspx?type=hats

Rewritten url:

/product/hats

Rewritten url after postback:

/product/hats?type=hats

which is actually equal to /product.aspx?type=hats&type=hats

So the type value is "hats,hats".

To avoid repeat of querystring variables simply check if the url is already rewritten:

protected void Page_Load(object sender, EventArgs e)
{
if ( !String.IsNullOrEmpty(Request.ServerVariables["HTTP_X_ORIGINAL_URL"]) )
{
form1.Action = Request.ServerVariables["HTTP_X_ORIGINAL_URL"];
}
}

Detailed description:

http://blogs.iis.net/ruslany/archive/2008/10/23/asp-net-postbacks-and-url-rewriting.aspx

SQL Server Express and IIS: Failed to generate a user instance of SQL Server due to failure in retrieving the user's local application data path.

2010-11-23T01:57:00.000-08:00

SQL Express user instancing fails with the default IIS 7.x configuration. To solve this you can do the following:

1. Create new application pool in IIS
2. Open Application Pool Advanced settings
3. Change Identity from ApplicationPoolIdentity to NETWORK SERVICE and confirm
4. Change the application pool that the web application belongs to by opening Advanced setting of the web application

3 ways to get date in SQL without time

2010-10-11T08:04:00.000-07:00

Here are 3 ways of getting date-only part of timestamp in SQL Server:

1. DATEADD( DAY, 0 , DATEDIFF(DAY,0, CURRENT_TIMESTAMP) )

2. CONVERT( datetime, FLOOR(CONVERT(float(24), GETDATE())) )

3. CAST( CONVERT(CHAR(8), GETDATE(),112) as DATETIME)

Passing Parameters to .NET Web Service as a Query String (GET Method) or POST Request

2010-09-02T13:58:00.000-07:00

First of all the way of passing parameters must be defined in web.config as follows:

<system.web>
<webServices>
<protocols>
<add name="HttpGet"/>
<add name="HttpPost"/>
</protocols>
</webServices>
</system.web>

Then the URL of the web service may include parameters as query string.
http://tempuri.org/webservice.asmx/MethodCaseSensitive?parameter1=yes&parameter2=123

MethodCaseSensitive is the name of web method to be performed as part of the webservice called webservice.asmx.

In case you need POST method of sending parameters just use a form and text fields as in the following example:

<form name="input" action="http://tempuri.org/webservice.asmx/MethodCaseSensitive" method="post">
<input name="parameter1" type="text">
<input name="parameter2" type="text">
<input value="Submit" type="submit">
</form>

Both of methods return XML response as it is defined in the web method.

The Web Service results can be easily checked using the .NET ability for integrated passing of parametersin a web interface:
http://tempuri.org/webservice.asmx?op=MethodCaseSensitive

The screen allows the user to enter web service parameters and submit them. The result is the same.

How to add custom shortcuts in Save / Open dialogs on Windows Vista

2010-02-18T12:36:00.000-08:00

1. Start Group Policy Editor by starting gpedit.msc
2. Navigate to:
User Configuration -> Administrative Templates -> Windows Components -> Windows Explorer -> Common Open File Dialog
3. Open "Items displayed in Place Bar"
4. Enter appropriate paths for you shortcuts

The changes take effect immediately.

Stop a postback by javascript with IE7

2010-01-16T04:35:00.000-08:00

Somehow the statement javascritpt:return false; doesnt work with IE 7. But there is a workaround by setting the event.returnValue to false.

OnClientClick="javascript:event.returnValue=false; return false;"

Minifying javascript source files.

2010-01-10T14:46:00.000-08:00

I just want to recommend you a very simple tool called JSMin, which helps minifying the javascript sources. This code improvement significantly decreases the download time because of the smaller page size. The toll successfully removes whitespaces and comments which are not needed on client side.

The tool is available as a script or a console application.

The usage of jsmin.exe is simple:
jsmin.exe output.js

Javascript Query String

2010-01-09T01:35:00.000-08:00

The query string is reachable through window.location.search property. Splitting it by & gives you list of passed GET parameters.

function GetPageParameter(param) {
var query ='';
if (window.location.search.length>3){
//removes '?' from the query string
query = window.location.search.substring(1);
}else{
return '';
}
params = query.split("&");
for (i=0;i1){
if (pair[0] == param) {
return pair[1];
}
}else{
return '';
}
}
return '';
}

var value = GetPageParameter("value");

How to fix a WebClient timeout issue

2009-12-21T11:31:00.000-08:00

The issue occurs when the time for generating the whole response of a WebClient request is longer than the default timeout (2 minutes / 60000 miliseconds) . So the solution is to increase this timout value. The WebClient class doesn't have such property or method, so you have 2 possibilities:

1. Use HttpWebRequest instead of WebClient and set its timeout by ReadWriteTimeout property. Of course the usage of this class is more complex than WebClisnt's one but it gives you more flexibility.

2. Make a derived class (wrapper) , which willset the timeout propery of the base class of the WebClient.

public class MyWebClient: WebClient
{
   //time in milliseconds
    private int timeout;
   public int Timeout
   {
           get {
               return timeout;
           }
           set {
               timeout = value;
           }
    }

    public MyWebClient()
    {
           this.timeout = 60000;
    }

     public MyWebClient(int timeout)
    {
           this.timeout = timeout;
    }

    protected override WebRequest GetWebRequest(Uri address)
     {
           var result = base.GetWebRequest(address);
           result.Timeout = this.timeout;
           return result;
    }
}

The usage is pretty much the same as the WebClient's usage but we have to specify the new timeout in the constructor or by setting the Timeout property:

MyWebClient wClient = new MyWebClient(1800000);
          
UTF8Encoding objUTF8 = new UTF8Encoding();

try
    {               
           byte[] data = wClient.DownloadData(url);

           File.WriteAllBytes(
             System.AppDomain.CurrentDomain.BaseDirectory + @"\files\output.xls", data);

           wClient = null;
           objUTF8 = null;
}
catch (Exception ex)
{
          objWebClient = null;
          objUTF8 = null;

}

As you see this timeout property solves the problems by client side. The server response should also have longer timeout for generating the response. It is set by machine.config or web.config - httpRuntime section. Note that the timeout in web.config is specified in seconds.

SQL – Cannot resolve collation conflict for equal to operation

2009-10-05T01:52:00.000-07:00

When the sql collation of strings is not equal but need to me compared we need to explicitly define the collation. The most common way is the using of the default database collation as in the example:

WHERE Table1.Name COLLATE DATABASE_DEFAULT=Table2.Name COLLATE DATABASE_DEFAULT

The collation change can be performed on tables joining, 'where' clausesq as part of stored procedures and functions, as well as database Default collation change.

Forcing downloading files by save dialog

2009-09-30T13:22:00.000-07:00

Here is the code snippet for downloading files with asp.net:

Response.Clear();

Response.AddHeader("content-disposition", "attachment;filename=" + filename);
Response.Cache.SetCacheability(HttpCacheability.NoCache);
Response.ContentType = "image/jpeg";

byte[] data = System.IO.File.ReadAllBytes(MapPath(url));
Response.BinaryWrite(data);
Response.Flush();
Response.End();

The key moment in forced save dialog is the header "content-disposition" with file attachment. This will tell to your browser to show you dialog and give you the possibility to get directly that file.
If you use attachment in "inline" header (appending it instead of "content-disposition") the file is gonna be opened in the same window. Browser back button can get you back on your page.

List of content types can be found here: MIME Reference

Visual Studio - Pre or Post-build events - copying example

2009-07-27T12:47:00.000-07:00

The Pre or Post events are simple and useful actions before or after building the solution, which can be used for performing customized actions to simplify deployment or testing.

The following example copying all output files to myproject\bin located in the solution directory.
Ex.
copy "$(TargetDir)*.*" "$(SolutionDir)myproject\Bin"

For reference see Macro table in MSDN

Batch files can be used as well for more complex predefined actions using the call statement Ex. call C:\Batch.bat

VB.NET How to encrypt and decrypt a string (password) using Rijndael cipher.

2009-04-24T01:38:00.000-07:00

The Rijndael algorithm is part of AES (Advanced encryption standard) which is approved by US government as enough secure way of protecting data.

The .NET offers pretty easy way for encrypting and decrypting data using Rijndael cipher:

Dim cryptography As New System.Security.Cryptography.RijndaelManaged
Dim ms As New MemoryStream()
Dim cs As New CryptoStream(ms, _
cryptography.CreateEncryptor(ASCIIEncoding.ASCII.GetBytes("[16 bytes ascii string]"), _
ASCIIEncoding.ASCII.GetBytes([16 bytes ascii string])), CryptoStreamMode.Write)
Dim sw As New StreamWriter(cs)
sw.Write(inputString)
sw.Flush()
cs.FlushFinalBlock()
ms.Flush()
Dim encryptedString As String = _
Convert.ToBase64String(ms.GetBuffer(), 0, CType(ms.Length, Integer))

The example encrypts inputString using for private key and salt two 16 bytes ascii strings. The private key and salt can be predefined as byte arrays . The result is 128 bit encrypted string stored in encryptedString.

Dim cryptography As New System.Security.Cryptography.RijndaelManaged
Dim buf As Byte() = Convert.FromBase64String(encryptedString.Trim())
Dim ms As New MemoryStream(buf)
ms.Position = 0
Dim cs As New CryptoStream(ms, _
cryptography.CreateDecryptor(ASCIIEncoding.ASCII.GetBytes("[16 bytes ascii string]"), _
ASCIIEncoding.ASCII.GetBytes("[16 bytes ascii string]")), _
CryptoStreamMode.Read)
Dim sr As New StreamReader(cs)
Dim decryptedString As String = sr.ReadToEnd()

The encrypted string is decrypted using the same private key and salt as in the encrytpion in and it is stored in decryptedString finally.

SQL: Transaction count after EXECUTE indicates that a COMMIT or ROLLBACK TRAN is missing.

2009-03-18T04:09:00.000-07:00

The following error message is got when the number of open transactions is different than the number of committed or rolled back transaction in the end of the stored procedure.

The global variable @@TRANCOUNT gives the number of opened transactions in the moment of check-up. If you are not sure what is number of opened transactions you can check the number at the end of the procedure and commit or rollback.

DECLARE @TranStarted bit
SET @TranStarted = 0

IF( @@TRANCOUNT = 0 )
BEGIN
BEGIN TRANSACTION
SET @TranStarted = 1
END
ELSE
SET @TranStarted = 0

-- do something
-- use select statements with locking rows or tables using
-- WITH ( UPDLOCK, HOLDLOCK ), WITH (HOLDLOCK)

IF( @@ERROR <> 0 )
GOTO Cleanup

--do something

IF( @@ERROR <> 0 )
GOTO Cleanup

-- if no errors commit the transaction
IF( @TranStarted = 1 )
BEGIN
SET @TranStarted = 0
COMMIT TRANSACTION
END

RETURN 1

-- in case of errors jump to the label cleanup to rollback the transaction
Cleanup:

IF( @TranStarted = 1 )
BEGIN
SET @TranStarted = 0
ROLLBACK TRANSACTION
END

RETURN 0

History support on Microsoft Ajax Library 3.5 SP1

2009-03-14T11:54:00.000-07:00

The history control maintain the browser back button. An explanation of the feature is located in the Readme documentation of the Microsoft Ajax Library 3.5 SP1 package.
For quick reference the links are listed below:

Managing Browser History Using Client Script: http://msdn.microsoft.com/en-us/library/cc488538.aspx
Sys.Application.addHistoryPoint: http://msdn.microsoft.com/en-us/library/cc488025.aspx
Sys.Application.navigate event: http://msdn.microsoft.com/en-us/library/cc488024.aspx

In order to allow the browser history feature without using the server-side ScriptManager control, it is necessary to add the following markup into the page for Internet Explorer versions before 8:

<iframe id="__historyFrame" src="/System.Web.Extensions/3.5.0.0/3.5.30729.1/empty.htm" style="display:none;"></iframe>

C# Implicitly Typed Local Variables and Arrays

2009-03-11T08:28:00.000-07:00

As a whole C# is a strongly-typed language. In other word the C# variables can hold explicitly defined data type.

From C# version 3.0 on the developer get the possibility to assign any values to a variable and the compiler to obtain accordingly the data type. It is not in the C# style as we know it but has some advantages of course.


var intVariable = 1235;
var stringVariable = "Hello";

The var keyword instructs the compiler to infer the type of the variable from the expression on the right side of the initialization statement. The may be a built-in type, an anonymous type, a user-defined type, or a type defined in the .NET Framework class library.

The biggest advantage of this new feature is the usage in LINQ query expression using anonymous data types. The anonymous type name is automatically generated by the compiler and is not available at the source code level, but his usage saves much developer's efforts.

For more information in MSDN click here

How to get the value of the server variable LOGON_USER

2009-03-06T03:36:00.000-08:00

1. Uncheck Allow Anonymous in the security tab of the site properties in IIS. At least Basic or Windows Authetication is needed.

2. Use the variable Request.ServerVariables("LOGON_USER") to get the full user name

How to open ComboBox (DropDown it) hosted in DataGridView with single mouse click.

2009-01-06T03:54:00.000-08:00

The usage of ComboBox in a DataGridView delivers some limitations of its usage. Very common problem is opening the ComboBox with single click of the mouse. By default double mouse click is needed because the first click selects the cell and the second click enters into Edit mode where the ComboBox fires its DropDown event.

We can do this using DataGridView.CellClick event. The following code is enough to open the ComboBox and fire its DropDown event.


Private Sub DataGridView1_CellClick(ByVal sender As System.Object, 
     ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) 
     Handles DataGridView1.CellClick
        'enters into edit mode
        DataGridView1.BeginEdit(True)

        'checking if the editing control is a combobox
        If TypeOf (DataGridView1.EditingControl) Is ComboBox Then

            'casting the editing control and fire DropDown event
            CType(DataGridView1.EditingControl, ComboBox).DroppedDown = True

        End If
End Sub

DataGridView.EditingControl represents the control hosted by the current cell.

Escape apostrophe in javascript and dynamic built scripts

2008-12-15T05:46:00.000-08:00

The apostrophe in javascript is its string delimiter. To render the apostrophe on the response without errors it must be escaped using backslash \.

alert('John\'s name') will produce message box with text: John's name.

Using asp.net usually the scripts are built dynamically on server side before rendering the page. Remember that the backslash is also escape character in C# and you have to put two backslashes to build the javascript correctly:

Response.Write("alert('John\\'s name');");

FTP over SSL with IIS is not supported.

2008-12-10T02:36:00.000-08:00

This is a common problem when you need more secure connection. Microsoft explains the features of their FTP server here:
http://support.microsoft.com/kb/283679

It is good to know that current FTP Service in IIS doesn't support Secure Sockets Layers (SSL). Of course that means your connection details and credentials to such service can be caught by Network listeners between you and the server. Therefore if you need secured connection you have to consider usage of Webdav over SSL or another FTP server which supports SSL.

A suggestion for free and easy to set up server is FileZilla FTP Server for Windows.

Edit shortcuts in Places bar in Save dialog / Open dialog in Windows

2008-11-24T00:58:00.000-08:00

It's absolutely boring to navigate to your most often used folder in windows save or open dialogs. Th purpose of Places bar is to help you to do this faster. The Places bar locations can be edited via Group Policy editor in Windows XP Pro and Vista. Use the following way:

1. Open gpedit.msc (Start->Run)
2. Navigate to User Configuration -> Administrative Templates -> Windows Components -> Windows Explorer -> Common Open File Dialog
3. Open "Items displayed in Places bar" and write down the locations you want with their paths. Symbolic names are also allowed like Desktop.

SQL: How to check for existing contraint

2008-11-11T05:50:00.000-08:00

Just an example how to get it form the database information schema:

IF NOT EXISTS(SELECT * FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE CONSTRAINT_SCHEMA='dbo' AND CONSTRAINT_NAME='IX_Constraint' AND TABLE_NAME='TableName')
BEGIN
ALTER TABLE [dbo].[TableName] WITH CHECK ADD CONSTRAINT ..... /* constraints */
END

How to set column width in a CheckBoxList in an ASP.NET page

2008-11-07T16:03:00.000-08:00

Maybe this is common problem since CheckBoxList control doesn't have set of parameters for obtaining column width and row height. But we always can use CSS for styling this control getting in mind he is rendered as html table or floated div tag.


<asp:checkboxlist runat="server" id="chkBoxList1" cssclass="chkBoxList" repeatcolumns="4" repeatlayout="Table">
</asp:checkboxlist>

Here we explicitly define the layout to be rendered as table (which is by default) and also need to define the css class "chkBoxList" in current page or web site theme.


<style>
.chkBoxList tr
{
   height:24px;
}

.chkBoxList td
{
   width:120px; /* or percent value: 25% */
}
</style>

Of course any other css styles can be attached here.

Only ASP.NET :)

SQL Stored Procedures - getting return value

2008-11-04T00:17:00.000-08:00

Starting directly with example:


CREATE PROCEDURE ProcessValue
(
@value int,
@returnValue int OUTPUT
)
AS
BEGIN
/* do calculation and processing and assign the result value to output parameter */
SET @returnValue = value + 5*value

END

The following calling of the procedure shows how to get output parameter.

declare @result int
EXEC ProcessValue 15, @result OUTPUT

Of course this example is pretty simple - only for showing how to use. For such usage the SQL scalar-valued functions are better way.

Way for localizing MessageBox in Windows Forms

2008-10-10T08:00:00.000-07:00

Very good article in code project, where you can see how the buttons of MessageBox can use custom text labels. The natural language of .NET platform will be overridden and only your labels will be shown.

http://www.codeproject.com/KB/miscctrl/Localizing_MessageBox.aspx

Actually if you use MessageBoxOptions in the parameters of MessageBox.Show(..) only the original labels are shown. But I don't think this is big problem.

How to map an extension for server side scripting - html to php

2008-10-06T13:04:00.000-07:00

Sometimes we need including some functionality or server includes into static web files - html. But changing the extension can lose current search engine index and rank. That is why leaving the fiels with the same name is the better way. Easy html files can be mapped to be parsed as php file.

IIS 7.0:
1. Open IIS Management Console
2. Open Web-site node
3. Open Handler Mapping
4. Add the extension as request path (*.html)
5. Set the handler application/library: something like C:\Program Files\PHP\php5isapi.dll
6. Name it and click OK

Apache:
Just add the following row in the .htaccess file:
AddType application/x-httpd-php .html

SQL Server 2005 - Out Of Memory exceptions connected to its RAM usage

2008-10-02T05:09:00.000-07:00

After the allocated RAM for SQL Server exceeds the System memory unexpected behavior of the server is present.

Here is a quick guide for configuring Sql server.

http://www.mattec.com/service/appnotes/820-0019.pdf

And remember: Never allocate less then 1 GB of RAM to SQL Server :)

VB.NET: General Exception Handling in Windows Forms

2008-10-01T09:08:00.000-07:00

VB.NET

My.Application.UnhandledException Event is the way for handling all unhandled exceptions in an windows forms application. The application raises this event when it encounters unhandled exception.
For using the event editing ApplicationEvents.vb file is needed. By default ApplicationEvents.vb is hidden. For openning (unhiding) it use Project Properties -> Application tab -> View Appication Events.
Then the handler can be added/edited as in the example below:


Private Sub MyApplication_UnhandledException( _
              ByVal sender As Object, _
              ByVal e As Microsoft.VisualBasic.ApplicationServices.UnhandledExceptionEventArgs _
              ) Handles Me.UnhandledException

          Try
              //write log, which is nessted in Application Data folder
              My.Application.Log.WriteException( _
                  e.Exception, _
                  TraceEventType.Critical, _
                  "Unhandled Exception!")

              //check up if the Event folder exists.
              //if not - create new one
              If Not EventLog.SourceExists("My software") Then
                  EventLog.CreateEventSource("My software", "My Software")
              End If

              //write event log, can be seen by Event Viewer
              EventLog.WriteEntry("My software", _
                  e.Exception.ToString(), _
                  EventLogEntryType.Error)
          Catch ex As Exception

          End Try

          // code for notifying the user with user friendly message
          ...................

          //set the default application action (closing) not to be performed.
          e.ExitApplication = False
End Sub

And from now on all unhandled exception in the application will be stored as exception information and stack trace in the application log file or in the Windows Event log and the user will receive friendly message.

C#

Of course most of my posts give examples with VB and C# when they are different. Now I will give up this pleasure to R. Newman with his great post "Top-level Exception Handling in Windows Forms Applications"

How to check the type of an object or control using VB.NET or C#

2008-09-24T02:16:00.000-07:00

The VB.NET check up is:


If (TypeOf sender Is TextBox)Then
 Dim txt As TextBox= DirectCast(sender, TextBox)
End If

And the C# code:


if (sender Is TextBox){
 TextBox txt=(TextBox)sender;
}

Error reporting in PHP run on IIS

2008-09-17T21:34:00.000-07:00

The PHP error reporting is controlled either by the php.ini file as a global setting or programatically, or using .htaccess.

The error reporting in php.ini is defined in "Error handling and logging" section.

error_reporting = E_ALL & ~E_NOTICE - shows all errors except E_NOTICE errors. E_NOTICE are possible errors which can occur even during normal program workflow - something like Microsoft's warnings.
display_errors = On
display_startup_errors = On

Programmatically the same settings are applied for current site like this:

ini_set('display_errors','1');
ini_set('display_startup_errors','1');
error_reporting(E_ALL & ~E_NOTICE);

In .htaccess the flags must be changed in the following way:

php_flag display_errors 1
php_flag display_startup_errors 1

Php error_reproting help -> http://php.net/error_reporting

URL Encoding - reserved and unsafe characters

2008-09-10T14:36:00.000-07:00

RFC 1738: Uniform Resource Locators (URL) specification is described in the following page. Also simple convertor is included.

http://www.blooberry.com/indexdot/html/topics/urlencoding.htm

Server.URLEncode(url)

applies these rules to the url. During getting an url parameter from the query string the value will be automatically decoded.

Javascript trace log

2008-09-02T07:48:00.000-07:00

Simple and useful tool can be found here:

http://v2.easy-designs.net/code/jsTrace/

Using it you can get rid of the alert messages while debug applications.

How to excute string with javascript

2008-09-01T11:17:00.000-07:00

Simply use eval().

eval('peformAction()') will execute

Adding a relationship between DataTables

2008-08-28T02:26:00.000-07:00

A DataTable can be related to another DataTable in the same DataSet using DataRelation object. Using DataRelation the navigation between DataTable (foreign key connection) becomes very easy.

An example for using Child Relation is located here:
http://msdn.microsoft.com/en-us/library/system.data.datatable.childrelations.aspx

Here is an example for using Parent Relation:

We have two DataTables: DataTableOrder (OrderId is foreign key to DataTableOrderDetails) and DataTableOrderDetails (Id is primary key)

//create dataset
DataSet dataSet = new DataSet();

//add existing tables to the DataSet
dataSet.Tables.Add(DataTableOrder );
dataSet.Tables.Add(DataTableOrderDetails);

// create relation between both tables
dataSet.Relations.Add(
dataSet.Tables[1].Columns["Id"],
dataSet.Tables[0].Columns["OrderId"]);

foreach (DataRow row in DataTableOrder .Rows)
{
//get parent rows using relation - all order details for current order
//use GetParentRows for relations 1 to many
DataRow dr=row.GetParentRow(dtm.ParentRelations[0]);
//check if there is a parent row
if(dr!=null){
Response.Write(row["OrderName"].ToString() +"->"+ dr["OrderDetails"].ToString() +"
")
}
}

Good working free CAPTCHA control for asp.net

2008-07-10T13:09:00.000-07:00

CAPTCHA stands for "Completely Automated Public Turing test to tell Computers and Humans Apart" and means software peace which makes user input challenges which are easy for solving by humans and difficult for machines. The purpose is to avoid spam or hackers attacks which can harm your data or make unpredictable responses.

This post will show you one very good CAPTCHA control, which is tested by me and works fine, even with ajax. It is easy for use and will save you time to develop such control.

Thanks for Mondor software.
http://www.mondor.org/captcha.aspx

Why don't you have .NET 3.5 as a selectable framework in IIS

2008-06-19T04:59:00.000-07:00

The reason is that the .NET Framework 3.5 delivers not whole new runtime machine, but only library extension of .NET 2.0. In other words there are no new CLR or new language compilers. But there are new available libraries and new versions of C# (3.0) and VB (9)

.NET Framework 2.0 includes the CLR, Winforms, Asp.NET and web services.

.NET Framework 3.0 includes in addition libries for WCF (Windows Communication Foundation), WPF (Windows Presentation Foundation) and Windows Workflow (WF).

.NET Framework 3.0 includes in addition libraries for AJAX, LINQ and REST

Finally you will see there is no problem with your IIS. You've just received some new additional and really good features for easier programming.

Gmail consider the mail as SPAM. How to avoid that?

2008-06-11T09:15:00.000-07:00

Obviously Gmail uses Sender-ID and DKIM to verify every email. That is why you need to modify DNS records for your domain using txt record. Here is a tutorial how to do that openspf.org.
You can build your txt records using the wizard and add them. You need something like:
record for domain.com in txt: v=spf1 a mx ~all
record for the mail server mail.domain.com in txt: v=spf1 a -all

Very good way to see how your html table will look like

2008-06-07T06:46:00.000-07:00

http://www.somacon.com/p141.php

Interactive tool for creating good looking html table using css. Make the table you want and copy and paste the generated css classes.

How to obtain current SQL Server version using sql query

2008-05-19T08:59:00.000-07:00

SELECT SERVERPROPERTY('productversion') As Version, SERVERPROPERTY ('edition') As Edition, SERVERPROPERTY ('productlevel') As Updates

The first columns shows current version as number, the second one is the edition (standard, express etc.) and the third one shows which version level the server belongs to (SP1, SP2 etc.)

Trick to start web application with another SQL Server database

2008-05-17T03:12:00.000-07:00

The following exception is thrown when you try to use one application with the another database. The problem is caused by asp.net membership provider which cannot recognize its schema.

The 'System.Web.Security.SqlMembershipProvider' requires a database schema compatible with schema version '1'. However, the current database schema is not compatible with this version. You may need to either install a compatible schema with aspnet_reqsql.exe (available in the framework installation directory), or upgrade the provider to a newer version.

First of all be sure the aspnet membership provider is registered on that database using aspnet_regsql.exe.

Then the solution is: taking the web application offline and then online using Web Site Administration Tool. That makes some changes in web.config in the pages tag and globalization if needed. Then you can go!

SQL pagination: get fixed number of rows page by page

2008-05-16T02:13:00.000-07:00

See the following examples:

SELECT * FROM
(SELECT ROW_NUMBER() OVER (ORDER BY Id) AS [SortNum], * FROM MyTable) As Tmp
WHERE SortNum Between 11 AND 20

or

WITH Tmp As
SELECT ROW_NUMBER() OVER (ORDER BY Id) AS [SortNum], * FROM MyTable)
SELECT * FROM Tmp
WHERE SortNum Between @StartRow AND @StartRow+@NumberOfRows-1

or

WITH Tmp As
SELECT ROW_NUMBER() OVER (ORDER BY Id) AS [SortNum], * FROM MyTable)
SELECT * FROM Tmp
WHERE SortNum Between (@page-1)*10+1 AND (@page)*10

The first one gives the second page of 10 records.
The second example shows the usage of WITH keyword and getting rows passed as parameter of stored procedure.
The third one shows you how to use 1 passed parameter as number of the desired page.

How to set your master page by the nested page

2008-05-11T10:53:00.000-07:00

The PreInit Page event n the nested page can be used for setting some Master page parameters.

protected void Page_PreInit(object sender, EventArgs e)
{
(this.Master as MasterType).Property = value;
}

Then the Master page will be loaded and rendered using these settings.
Master is the reference to the Master page. MasterType is the type of master page used.
Property is the public variable which must be set before loading page.

Using Page_PreInit the Master page can be set dynamically.

Sql Date Manipulation

2008-05-09T13:05:00.000-07:00

DATEPART (datepart, date) returns the desired part of the date specified by datepart parameter: year,
quarter, month, dayofyear, day, week, weekday, hour, minute, second, millisecond.

Example: DATEPART(month, GETDATE()) returns current month number

DAY(date), MONTH(date), YEAR(date) return respectively the number of the day, month or year of the passed date.

To add or subtract date parts from a given date use this function:
DATEADD (datepart , number, date)
where datepart is one of the following parameter (datepart): year,
quarter, month, dayofyear, day, week, weekday, hour, minute, second, millisecond.

Example: DATEADD(day, -7, GETDATE()) return the date week ago.

DATEDIFF (datepart, startdate, enddate) gives you the difference between two dates in desired date part (see DATEPART date parts above). Startdate should be date before end date. Otherwise a negative number will be returned.

Example: DATEADD(day, DATEADD(day, -7, GETDATE()), GETDATE()) return 7 days.

Ajax Error Message:The state information is invalid for this page and might be corrupted

2008-04-28T04:41:00.000-07:00

The message is shown when a page with partial postback regions (update panels) is refreshed by F5 or browser's refresh button and then a new partial postback request is performed. In this case the information stored in the page has been changed and causes not to be possible to perform partial postback. For pages like these the page parameter EnableEventValidation must be set to false:

<%@ Page EnableEventValidation="false" ....

Another case is described here: http://support.microsoft.com/kb/323744

How to execute string (custom built sql query ) in a stored procedure

2008-04-25T06:14:00.000-07:00

sp_executesql executes string in a stored procedure. It is used in more complex queries which we need to build concatenating strings. The string is run as a batch. The following example gets the TOP records from a table matching predefined conditions.

CREATE PROCEDURE [GetTOPRecords]
@count varchar(6),
@conditions nvarchar(300)
AS
BEGIN

DECLARE @SQL nvarchar(1000)

SET
@SQL='SELECT
TOP '+ @count + ' * FROM RecordsTable
WHERE ' + @conditions

EXEC sp_executesql @SQL

END

The @count and @conditions are passed as parameters. The execution string is built run-time and executed. If you don't need any conditions here just pass the string ' 1=1 ' as @conditions.

How to build unsafe C# code with Visual Studio

2008-04-24T11:22:00.000-07:00

Unsafe code may only appear if compiling with /unsafe

This appears as an error when you try to compile assembly which contains unsafe code in release mode.
You must change the compiler options using project's Properties page -> Build -> and check Allow Unsafe Code. Consider if you want to use unsafe code :)))

Javascript: How to check if the variable is a number?

2008-04-22T02:53:00.001-07:00

There are some ways for doing this but I think the following is the most easiest and convenient for use:

if (! isNaN(variable)) {
//code here
}

isNaN comes from is Not A Number and can be used for understanding if the variable is a number.

How to maintain the view state of dynamically added control in an asp.net page

2008-04-15T09:45:00.000-07:00

First of all you must read these articles:

The viewstate of a dynamically added control can be saved for maintaining the state of the control after postback.
This can be achieved by adding the controls before the Load Viewstate stage (see the page stages in the articles above). Therefore the viewstate information ( control value) from the request will be applied to already added controls as they are defined already in the page.
The right place of adding dynamic controls is Page_Init. Use Page_Init also for defining dynamically master pages and themes.

Understanding AutoEventWireup attribute in Asp.net page. Event handlers.

2008-04-15T07:35:00.000-07:00

The AutoEventWireup attribute indicates if the page events are auto-wired up. If the attribute is set to true .Net framework searches automatically for methods which names are created in the way Page_xxxxx (Page_Load, Page_Init etc.) and connects them to the events. Otherwise the developer or the environment must do that using delegates:

this.Load += new System.EventHandler(this.Page_Load);

for all handled page events. Setting AutoEventWireup to false is the better way because of the performance -> the framework uses only the methods with code!

The attribute can be set on several places: in machine.config, web.config and for every page.

Note:
The note is not connected directly to the page events, but to events of postback controls like button, linkbutton etc.
In VB.NET the event handlers can be attached to the events using the keyword "Handles".

Protected Sub LinkButton1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles LinkButton1.Click

This method will handle the event Click and will work like adding the attribute
OnClick="LinkButton1_Click" to the LinkButton tag. But NEVER USE both of the ways at the same because this will invoke the method twice!!
Consider using keyword "Handles" OR OnEvent="", but never use them together.

How to covert System.Drawing.Color to a HTML/CSS color value

2008-04-10T12:31:00.000-07:00

The System.Drawing.Color represenation of the color including the alpha color element:
alpha, red, green, blue.
The process is simple - convert the decimal color representation to a hexadecimal, then remove the alpha hexadecimal value from the string and concatenate to '#'.

Dim HTMLColor As String = Hex(color.ToArgb())
HTMLColor = "#" + HTMLColor.Substring(2)

where "color" is an instance of System.Drawing.Color

There is a difference between VB.NET and C# in getting the hexadecimal value as string. The C# fans can use the folloing code:

string HTMLColor = color.ToArgb().ToString("X8");
HTMLColor = "#" + HTMLColor.Substring(2);

The opposite process can be accomplished by ColorTranslator' services:
Dim color As System.Drawing.Color = System.Drawing.ColorTranslator.FromHtml("#e5e5e5")

Javascript string functions

2008-04-04T05:41:00.000-07:00

Let's see how to use replace() function for replacing string with another one. The specialty here is the usage of regular expressions to replace the string if it occurs more than once in the source string.

replace('aa','a'); is gonna replace only the first occurrence of the 'aa'.
replace(/aa/g, 'a') will replace all occurrences of the 'aa' string.
replace(/A/i, 'b') will replace the occurrences of 'A' or 'a' with 'b' - case insensitive.

Very common problems are the special character replacement. These characters should be escaped using \.

replace(/\./g, '') will replace all occurrences . with an empty ('') string.

Unicode and hosted PHP

2008-03-12T03:37:00.000-07:00

To make apache to work with unicode you must add into .htaccess the following:

php_value default_charset utf-8
AddDefaultCharset utf-8

.htaaccess geve you the ability to change PHP settings without changing php.ini

How to get the whole url on the page in PHP

2008-02-26T07:45:00.000-08:00

Here is a usefull function for getting current url:

function GetCurrentURL() {
$url = '';

if ($_SERVER["HTTPS"] == "on")
{
$url .= "https://";
}
else
{
$url .= "http://";
}
if ($_SERVER["SERVER_PORT"] != "80") {
$url .= $_SERVER["SERVER_NAME"].":".$_SERVER["SERVER_PORT"].$_SERVER["REQUEST_URI"];
} else {
$url .= $_SERVER["SERVER_NAME"].$_SERVER["REQUEST_URI"];
}
return $url;
}

Get UrlRewritingNet to work with IIS 7.0

2008-02-24T09:45:00.000-08:00

There is a well known problem using url rewriting functionality with UrlRewritingNet and IIS 7. The problem can be solved by setting the pipeline mode of the application pool to be in classic mode. Looking forward for the next version :).
Actually the url rewriting functionality can be achieved much easier with IIS 7.

AJAX: Timeout problem by asyncronous postback

2008-02-13T04:58:00.000-08:00

The most common cause of this problem is the time of asyncronous response. It occur when the response takes more than 90 seconds. First of all be sure that there is no client script in the update panel. Use

ScriptManager.RegisterStartupScript(Me.Page, Me.GetType(), "tmp", "<script type='text/javascript'></script>", False)

to register such scripts during loading page.

If the reason is long calculations on the srever you can change the asyncronous timeout in the ScriptManager tag.

<asp:ScriptManager ID="ScriptManager1" AsyncPostBackTimeOut="3600" runat="server" />

This makes the response to be valid an hour.

How to sum values in Excel only from visible cells

2008-02-09T15:19:00.000-08:00

There is a good article in microsoft support site for this problem and the example works fine.

How to use a VBA Macro to Sum Only Visible Cells

see also how to create user defined functions (UDF)
in Excel

Creating User Defined Function in Excel (UDF)

2008-02-09T15:06:00.000-08:00

You have to use VBA for making User Defined Function in Excel (UDF).
Click on Developers tab in the ribbon (Excel 2007) then click on Visual Basic or use Alt+F11.
Then insert a new module by Insert->Module and write your function there.
The functions will be inlcuded Insert Function dialog box in "User Defined" category.

To use the functions in another excel documents you must save them in your own add-in by saving the file as add-in file .xla or .xlam for Excel 2007. Then load the add-in by Start->Excel Options->Add-ins->Go.

How to enable VBA on Excel 2007 (Microsoft Office 2007)

2008-02-09T14:57:00.000-08:00

The developer's functions of excel and VBA are disabled by default. They can be unlocked using Start->Excel Options window. Check "Show developers tab in the Ribbon" in Popular section. After clicking OK the developers tab is shown at the last place in the ribbon.
Another important thing is the saving xls documetns with recorded macros or inlcuded VBA scripts. You must save the file by Save As dialog box as an Excel Macro-Enabled Workbook with extension .xlsm .

Error rendering a custom control

2008-02-02T03:37:00.000-08:00

Maybe this is a little MS Visual Studio bug. It is connected to the control registering in the page in case of using a control defined in App_Code folder, not in another assembly. The exception thrown while opening design view of the page is:

Error Rendering Control - [control] An unhandled exception has occurred. There was an error parsing the theme. The assembly attribute cannot be an empty string.

So the VS environment doesn't recognize the control defined in the App_Code. Therefore the control regitration must inlcude the assembly name - "App_Code"

<%@ Register TagPrefix="my" Namespace="MyControls" assembly="App_Code" %>

or

<add tagPrefix="my" namespace="MyControls" assembly="App_Code" />
in web.config - pages/controls section

SQL Server Express permissions

2008-01-20T12:08:00.000-08:00

Fix for exceptions like these:
"CREATE DATABASE permission denied in database 'master'",
"EXECUTE permission denied on object "
"SELECT permission denied on object"

Asp.NET uses the NETWORK SERVICE account (for Windows Server 2003) and ASPNET user for Windows XP. If we use windows authetincation for using sql express we need to add these users as sql server logins:
SQL Server manager -> Security -> Logins -> add "NT AUTHORITY\NETWORK SERVICE" or ASPNET
Then click on the properties menu of the login and make the login dbcreator. This will fix the first of the exceptions above. Then with User Mapping setting we can add permissions explicitly to the desired database -> dbowner gives all needed permission.

How to get Profile instance out of asp.net page,

2008-01-18T08:18:00.000-08:00

The way of getting Profile instance from a page context is Profile.GetProfile(). But how to do this when you need to get it from App_Code for instance. Here is the way:

MembershipUser mUser = Membership.GetUser(UserId);
ProfileCommon prof = (ProfileCommon)System.Web.Profile.ProfileBase.Create(mUser.UserName);

the object "prof" has all profile fields as in a page.

How to set page/script timeout on an asp.net page

2008-01-13T04:41:00.000-08:00

The solution is pretty simple. Use Server.ScriptTimeout to set the timeout for the script in a page. The value is measured in seconds.

Server.ScriptTimeout = 3600

Use this in Page_Load event. The example makes the timeout to be an hour.

NOTE: using compilation debug="true" will ignore script timeout and it won't work. Make sure the debug value is false on the release version of web.config

FormsAuthentication.Authenticate vs Membership.ValidateUser

2008-01-04T13:30:00.000-08:00

FormsAuthentication.Authenticate can be used with clear passwods to check user authentication:
if(FormsAuthentication.Authenticate(Username.Text, Password.Text))
{
FormsAuthentication.RedirectFromLoginPage(Username.Text, false);
}

This doesn't work if the password format is not clear. Asp.NET membership provider offers you Clear, MD5 or SHA1 represented passwords.
In case of using MD5 or SHA1 (specified in web.config, SHA1 is default for hashed passwords) the checking for user credentials should be done by Membership.ValidateUser which delivers the provider model for user authentication.

if( Membership.ValidateUser(curentUserName, pwd)){
FormsAuthentication.RedirectFromLoginPage(Username.Text, chkPersistent.Cheked);
}

The other things of authentication process can be left to the Asp.Net provider.

See also for web.config: authentication and authorization, machine key generation, password format, password salt ...

How to use SQL Express database for more than one application

2008-01-02T23:38:00.000-08:00

Somethimes we need to use one database for more than one application, web, desktop or service.
The only thing to do is to get rid of the generation of a new user instance by the connection string in web.config. Assure that User Instance=False in the connection string and try again.

Javascript: How to cancel leaving page without saving

2007-12-17T01:18:00.000-08:00

Preparing the javascript:
string jscript = "var needToSave= false;" +
"window.onbeforeunload = confirmExit;" +
"function confirmExit(){" +
"if (needToSave){" +
"return 'Are you sure you want to leave the page without saving?';" +
"}" +
"}";

Registering the script - safe for ajax:

ScriptManager smgr = ScriptManager.GetCurrent(Page);
ScriptManager.RegisterStartupScript(this.Page, this.GetType(), "temp", "", false);

On every field that changes the data and requires saving put:
control.Attributes.Add("onkeydown","javascript: needToSave=true;")

on the button that make save postback add:
control.Attributes.Add("onclick","javascript: needToSave=false;")

Page Cannot Be Found Issue on IIS 6 on Windows 2003

2007-12-11T10:10:00.000-08:00

Also:
HTTP 404 - File not found

First of all be sure that the default document list contains the page you are requesting (IIS -> Server Node -> Site node -> right mose click -> Properties -> Documents
Also set the necessary permission to the web folder (NETWORK SERVICE must have read/write rights)
Check if the asp.net status is allowed (IIS -> Server Node -> Web Service Extensions -> Asp.net must be allowed). This can be done during the installation of IIS.

ASP.NET Export content to Excel files.

2007-12-06T13:29:00.000-08:00

The most common problem during exporting page content to an excel file is the following exception: RegisterForEventValidation can only be called during Render();
The only thing you need to do is to set enableEventValidation ="false" in web.config (affects all your pages) or in the head page line.

If you want to render a control into an excel file (using HTML representation) the VerifyRenderingInServerForm() method must be overridden.

public override void VerifyRenderingInServerForm(Control control){}

This confirms that an HtmlForm control is already rendered.

... and the example - rendering existing gridview control into a xls file:
Response.Clear();
Response.AddHeader("content-disposition", "attachment;filename=file.xls");
Response.Charset = "";
Response.Cache.SetCacheability(HttpCacheability.NoCache);
Response.ContentType = "application/vnd.xls";
System.IO.StringWriter stringWrite = new System.IO.StringWriter(); ;
System.Web.UI.HtmlTextWriter htmlWrite = new HtmlTextWriter(stringWrite);
htmlWrite.Write("text text");
htmlWrite.WriteBreak();
GridView1.RenderControl(htmlWrite);
Response.Write(stringWrite.ToString());
Response.End();

How to recover Mozilla Firefox Bookmarks

2007-11-06T00:55:00.000-08:00

Very strange problem. Sometimes firefox' bookmarks dissapear. May be this is connected with NTFS problems (sometimes solved by chkdsk c: /f). But the best way to recover the bookmarks is to get them again from the last firefox archive. They are in

C:\Documents and Settings\[username]\Application Data\Mozilla\Firefox\Profiles\pypbblhs.default\bookmarkbackups

and the last archive must be ranamed and put into

C:\Documents and Settings\[username]\Application Data\Mozilla\Firefox\Profiles\pypbblhs.default

This solved my problem :)

Problems with using SQL Server instance by Windows remote desktop

2007-10-28T11:04:00.000-07:00

'Failed to generate a user instance of SQL Server due to a failure in starting the process for the user instance. The connection will be closed.'

This problem occurs when the user uses remote desktop and logs into the system for the first time. If the user logs in at first locally and then uses remote desktop the problem doesn't occur.

Microsoft describe the problem in the article
http://support.microsoft.com/?id=896613
It is enough to request them to send you a link for the fix (windows update) and wait a few hours. The fix cannot be downloaded directly because of need of additional testing. But it works fine for me.

A tip for avoiding null values in aggregate functions in sql

2007-10-24T23:37:00.000-07:00

Sometimes the aggreagete functions in SQL returns null value - when the data doesn't meet selection criteria defined in the query.
We can return 0 instead NULL with (ISNULL (column, 0)).

For example:
SELECT
(ISNULL (SUM (salary), 0)) As Total
FROM Salaries
WHERE
UserId=@UserId

Using such statement avoids checking for null values in the code.

How to hibernate Windows.

2007-10-24T01:25:00.000-07:00

What is Hibernate? This is a process of copying all RAM content to the hard disk and possibility to continue your work from the last state after shutting down the system.
The required things are:
1. Your motherboard must support this Function
2. Hard disk space at least your RAM size.
3. Enabled Hibernation in Windows
(Display Properties -> Screen Saver -> Monitor Power -> Hibernate -> Enable Hibernation check box)

Button "Hibernation" is shown after clicking Shut Down. If you dont have this button, you can show it by pointing "Stand By" button on the shutdown dialog box and hold Shift button. :-) I dont know why? It seems the newer versions of XP doesn't show Hibernate button.

ASP.NET How to access the EmptyDataTemplate controls from OnRowCommand in GridView

2007-10-23T01:44:00.000-07:00

The way of getting access to the controls in EmptyDataTemplate is similar to the way of accessing controls in the same data row in the gridview.

For example - inserting value in the empty gridview:


protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
{
 if (e.CommandName == "Insert") {
  TextBox txt  =
    (((Control)e.CommandSource).NamingContainer).FindControl("txtTest") as TextBox;

    //do insert action
 }
}

Another way to do this is by getting EmptyDataTemplate table and its controls:

if (e.CommandName == "Insert")
{
   Table table = (Table)GridView1.Controls[0];
   TextBox txtTest= (TextBox)table.Rows[0].FindControl("txtTest");

   //do insert actions
}

ASP.NET How to set and get key values for every gridrow in a gridview.

2007-10-22T02:04:00.000-07:00

Setting primary key values during data binding:


gvUsersInRoles.DataSource=taUsersInRoles.GetData();
gvUsersInRoles.DataKeyNames = new string[] { "UserId", "RoleId" };
gvUsersInRoles.DataBind();

This example uses composite primary key for showing more complicated usage.

Getting primary key values during performing row command (command, insert, delete, update):


Guid uid = new Guid(gvUsersInRoles.DataKeys[e.RowIndex]["UserId"].ToString());
int pid = int.Parse(gvUsersInRoles.DataKeys[e.RowIndex]["RoleId"].ToString());

Getting the the newly created primary key after sql insert operation

2007-10-19T12:36:00.000-07:00

INSERT INTO Table(COL1) VALUES('213')

SELECT @@IDENTITY

or

Return SCOPE_IDENTITY()

or

Return IDENT_CURRENT('TableName')

SCOPE_IDENTITY and @@IDENTITY return the last identity values that are generated in any table in the current session.

SCOPE_IDENTITY returns values inserted only within the current scope.

@@IDENTITY is not limited to a specific scope. It returns the last identity value after performing all scopes (including triggers).

IDENT_CURRENT returns the last identity value generated for a specific table in any session and any scope. In othe words it teturns the last value inserted into 'Tablename'

Using ASP.NET SQL Server Registration Tool (aspnet_regsql.exe) with SQL Express 2005 databases

2007-10-18T06:16:00.000-07:00

The aspnet_regsql can be found in
[HDD Drive]:\WINDOWS\Microsoft.NET\Framework\v2.0.50727

The command used for adding asp.net 2.0 membership stuff is

aspnet_regsql -A all
-C "Data Source=.\EXPRESS;Integrated Security=True;User Instance=True"
-d "[database path]"

-d - specifies the database by actual database path

-A all|m|r|p|c|w -

Adds support for one or more ASP.NET application services. Service identifiers can be specified together or separately. The following identifiers are used for ASP.NET application services:

all - All services, including common tables and stored procedures shared by the services

m - Membership

r - Role Manager

p - Profile

c - Web Parts Personalization

w - Web Events

-C - Specifies the connection string to the computer running SQL Server where the database will be installed, or is already installed. This option is not necessary if you specify only the server (-S) and login (-U and -P, or -E) information.

How to set up SMTP Virtual Server with IIS

2007-10-16T13:59:00.000-07:00

Exception: Mailbox unavailable. The server response was: 5.7.1

Check the following settings in IIS

IIS -> Default SMTP Server -> Properties -> Access
1. Authentication -> Anonymous access -> Checked
2. Connection control -> Only the list below -> Add current web server ip
Relay restrictions > Relay > - Only the list below -> Add current web server ip

Also add localhost ip here 127.0.0.1 . If DNS lookup doesnt work you can add alias for 127.0.0.1 in your
C:\WINDOWS\system32\drivers\etc\hosts file.

Also it is necessary to have these lines in web.config

<system.net>
<mailsettings>
<smtp deliverymethod="network" from="user@domain.com">
<network host="localhost" port="25" defaultcredentials="true">
</network>
</smtp>
</mailsettings>
</system.net>

How to validate dates in ASP.NET

2007-10-16T06:49:00.000-07:00

The simpliest way is by using range validator control and define date bounds


<asp:textbox id="textbox1" runat="server">
</asp:textbox>
<asp:rangevalidator id="valRange" runat="server" controltovalidate="textbox1" 
maximumvalue="31/12/2010" 
minimumvalue="1/1/2000" type="Date" 
errormessage="*" display="dynamic">
*
</asp:rangevalidator>

Some facts about Sessions in ASP.NET

2007-10-15T13:46:00.000-07:00

The kind of objects that can be stored in a session variable depends on which mode is used:
InProc Mode- objects stored in session state are actually live objects, and so you can store whatever object you have created.
State Server or SQL Server mode, objects in the session state will be serialized and deserialized when a request is processed. So make sure your objects are serializable and their classes must be marked as so. If not, the session state will not be saved successfully.

To enable sessions in the asp.net site you need to
include a pages attribute in web.config:


<pages enablesessionstate="true">

or enable SessionState in the Page directive in your page :

<%@ Page enableSessionState = "true" %>

Also, the System.Web.SessionStateModule should exist in your
httpModules section in the application configuration.

<httpModules>
<add type="System.Web.SessionState.SessionStateModule" name="Session" />
</httpModules>

Page attributes in ASP.NET for extending System.Web.UI.Page

2007-10-15T12:40:00.000-07:00

PageBaseType – Takes a string value defining the base type that will be used for the bage. The default is System.Web.UI.Page. The value gets overridden by the value in the inherits attribute in the standalone file.

userControlbaseType – specifies the base type for controls to be used when the page is standalone.

After implementing classes that extend System.Web.UI.Page or System.Web.UI.UserControl their type can be determined for all pages in the site by their page attributes in web.config. Another way to define the type of the base class is by explicitly defined property CodeFileBaseClass=... in the Page or Control tag (first row in the page).

The using of Page properties (fields) or custom methods by user control is possible by converting Page field to the base page type:


CType(Me.Page, PageBase).Property
CType(Me.Page, PageBase).Method()

Add/remove columns, changing default values in a SQL Server 2005 table

2007-10-11T09:19:00.000-07:00

Add new column in a table with checking for existence.
IF NOT EXISTS(SELECT * FROM syscolumns WHERE id=object_id('ColumnName') and name='TableName')
 ALTER TABLE TableName ADD ColumnName bit not null default 0

Changing default values in a SQL Server 2005 table
ALTER TABLE [Table]  ADD CONSTRAINT
    ConstrName  DEFAULT 0 FOR ColumnName

DropDownList in GridView

2007-09-24T03:00:00.000-07:00

It is necessary to convert bound field to a template field, then set your DropDownList up. In the example it is bound to an ObjectDataSource. It is possible to use statement like (SelectedValue=<%# Bind("Field") %>), but this way is good only for read-only gridview.
Any postback can throw an exception connected to the Bind/Eval way of binding -
'Databinding methods such as Eval(), XPath(), and Bind() can only be used in the context of a databound control'.

The better way is by using customized code during processing the ItemUpdating event:


<asp:TemplateField HeaderText="Header text">
  <ItemTemplate>
    <asp:DropDownList ID="ddlItem"
        runat="server" OnDataBound="ddlItems_DataBound"
        DataSourceID="ObjectDataSource1"    AppendDataBoundItems="false"
        DataTextField="Name" DataValueField="Id" >
    </asp:DropDownList>
  </ItemTemplate>
</asp:TemplateField>


protected void ddlItems_DataBound(object sender, EventArgs e)
{
  DropDownList ddl = (DropDownList)sender;
  GridViewRow gvr = (GridViewRow)ddl.NamingContainer;
  if (gvr.DataItem != null)
  {
      string id = ((DataRowView)gvr.DataItem)["Id"].ToString();
      ddl.ClearSelection();
      ListItem li = ddl.Items.FindByValue(id);
      if (li != null) li.Selected = true;
  }     
}

It is important to use cast of sender, not direct calling to the GridView1 control. Every GridViewRow is actually DetailsView object.

protected void GridView1_RowUpdating
 (object sender, GridViewUpdateEventArgs e)
{     
 DropDownList ddl =
   (DropDownList)(((GridView)sender).Rows[e.RowIndex].FindControl("ddlItems"));
 e.NewValues["Id"] = ddl.SelectedValue;
}

Confirmation dialog to a GridView delete option

2007-09-23T05:57:00.000-07:00

Actually it is not possible to attach client confirmation to the delete command filed. But it is pretty easy to do this by template field. The only think you have to do is to set command name to be "Delete" (CommandName="Delete"). GridView event handlers are responsible for the other things of delete process.


<asp:TemplateField>  
         <ItemTemplate>
         <asp:LinkButton ID="delete1"
  runat="server"
  OnClientClick=
  "return confirm('Are you sure you want to delete this record?');"
         CommandName="Delete">Delete
         </asp:LinkButton>
         </ItemTemplate>
</asp:TemplateField>

Passing data between two pages with Cross-page Postback and Server.Transfer

2007-09-21T12:08:00.000-07:00

The ASP.NET control, that cause postback, post back to the page for processing. That page can be current page or another page. Every control that cause postback can be configured to post to a different page - this postback is called cross postback and is often used for getting information from the pages in the multi page form, especially convenient for creating wizards.

<asp:Button
ID="Button1"
PostBackUrl="~/TargetPage.aspx"
runat="server"
Text="Submit" />

Cross-page post back is similar to Server.Transfer method, but there are some imporrtant differences. Server.Transfer conserves the post data between pages and also it keeps the url. And also it has a documented bug with getting url parameters from the source page. The Server.Transfer method is a server-based operation whereas cross-page postback is a client-based transfer. The main aim of the Server.Transfre method is to reduce client request to the server which makes it faster than Response.Redirect().
Anyway the cross-page postaback can throw the user on another page but with possibility to get the post data.

if (Page.PreviousPage != null)
{
TextBox SourceTextBox =(TextBox)Page.PreviousPage.FindControl("TextBox1");
if (SourceTextBox != null) { Label1.Text = SourceTextBox.Text;
}
}

there is also possibility to get public properties from the source page with decalring the source:

<%@ PreviousPageType VirtualPath="~/SourcePage.aspx" %>

getting the whole source page:

SourcePage_aspx sourcePage;
sourcePage = (SourcePage_aspx) PreviousPage;
Label1.Text = sourcePage.CurrentCity;

With PreviousPage.IsCrossPagePostBack we can determine whether the page was invoked from a cross-page posting.

Resources:
http://msdn2.microsoft.com/en-us/library/ms178139.aspx
http://www.developer.com/net/asp/article.php/3299641
http://www.codeproject.com/useritems/CrossPagePosting.asp

Script Callbacks in ASP.NET

2007-09-19T12:36:00.000-07:00

I am sure that every web developers hates page refresh. And everyone chases the way to make its page more interactive without postback. The best way is client side scripting, but it is not enough to generate all page activity. Javascript based technologies like callbacks and AJAX are at the bottom of the effcicient developer's code.
Here are some good posts for callback technology in ASP.NET 2.0.

http://msdn.microsoft.com/msdnmag/issues/04/08/cuttingedge/

http://www.developer.com/net/asp/article.php/3485991

http://www.mredkj.com/vbnet/scriptCallback.html

At the core, ASP.NET script callbacks consist of some client-side JavaScript code needed for asynchronous communication to the server. The first requirement for using the callbacks is that some server-side code awaits client calls. The client-side callback intermediary manages the call while the user continues to see the old page and interact with it.

Getting fixed number of rows with SQL Select query

2007-09-18T11:04:00.000-07:00

The syntax for SQL Server:
SELECT TOP 10 id, name email
FROM person

The syntax for MySQL:
SELECT id, name email
FROM person
LIMIT 10

These examples get the first (top) 10 rows in the query.

I will describe also the paging technology of the asp.net.

Using DataTable (DataView) Filter expressions, Sorting

2007-09-17T15:52:00.000-07:00

In some cases it is necessary to be made some calculations or data filtering and sorting of local data - already received from a database. These things can be made with the DataTable or DataView classes in a way similar to SQL Select queries.
When we have a filled DataTable we can easy retrieve only the rows we need with DataView.RowFilter. This property gets or sets the expression used to filter which rows are viewed in the DataView (often used for DataSourse in data components).

DataTable dt= ......... //filling the data table
DataView dv= dt.DefaultView;
dv.RowFilter="AreaId="+searchId+" AND SubAreaName LIKE 's*'; //getting all records for searched area whic name starts with 's'
dv.Sort="Name desc, number asc"; //sorting data

dv.RowFilter = "Name LIKE 's*'" // values that start with "s"'
dv.RowFilter = "Name LIKE '%s%'" // values that contain 's'
dv.RowFilter = "Name NOT LIKE 's*'" // values that don't start with 's'
dv.RowFilter = "Name <> 'MyName'" // values different than 'MyName'
dv.RowFilter = "Name IN ('MyName','MySecondName')" // value equal to 'MyName' or 'MySecondName'

If the pattern string in a LIKE statement contains special characters like * % [ ], they must be escaped in brackets [ ] in this way [*], [%], [[] or []].

RowFilter is an expression string that can be evaluated to true or false, and uses the syntax described in the DataColumn.Expression documentation.

It is very useful to use also aggregate functions for calculation. For example

dt.Columns("ItemCount").Expression = "Count(ItemID)"

dt.Columns("ItemCount").Expression = "FirstName = 'John'"

dt.Columns("ItemCount").Expression = "Date < #1/31/82#"

dt.Columns("ItemCount").Expression = (LastName = 'Smith' OR LastName = 'Jones') AND FirstName = 'John'


Here is the MSDN reference for the filter expressions:
http://msdn2.microsoft.com/en-us/library/system.data.datacolumn.expression(VS.71).aspx

SQL Server Express Edition attaching and using problems

2007-09-14T02:36:00.000-07:00

"Cannot open user default database. Login failed.
Login failed for user ......"

This problem occurs very often while the developer uses Visual Studio and testing in a browser at the same time. The reason is the already opened connection to the database in the VS environment. For example every time when the developer edit DataSet connected to current database this connection stays opened. The solve this problem the connection to the db has to be closed by the right mouse button -> Close Connection in the Server Explorer tab.

Another problem with attaching database and using its connection is:
"An attempt to attach an auto-named database for file ..... failed. A database with the same name exists, or specified file cannot be Opened, or it is located on UNC share."

1 . The first thing that has to be done is to try to attach the database manually with Microsoft SQL Server Management Studio.

2. The data folder permissions have to be set to "Modify" for ASPNET account and NETWORK SERVICE for windows server 2003

3. Make ASPNET user a member of SQLServer2005MSSQLUser$server$SQLExpress group

4. Add new Login to the SQL Express server for ASPNET (NETWORK SEVICE) user

5. In the connection string User Instance=True has to be checked. It works only if SQL Server uses Windows Authentication mode.
Changing the authetication mode can be done by SQL Server Management Studio with right mouse click on the computer name and Properties -> Security.
When Integrated Security=SSPI in the connection string is used make sure you are using in system.web sections of the web.config and also make sure that a windows account for the "Anonymous User" is selected in the access section in IIS.

6. Also the sql settings in c:\Documents and Settings\<username>\Local Settings\Application Data\Microsoft\Microsoft SQL Server Data\ can be deleted and the sql service restarted.

ASP.NET Request Validation has detected a potentially dangerous client input value

2007-09-12T06:54:00.000-07:00

This exception occurs when the server meet content containing un-encoded HTML. This is action for preventing script atacks, for example <script> alert("blabla")</script> can be executed. In this way other harmful code can be executed. The request validation feature of ASP.NET doesn't allow this to be done.
To disable request validation on a page you must set the validateRequest attribute of the Page directive to false. The developer has to ensure that the content is properly encoded.
One more way to disable it is by web.config. You have to set
<configuration>
<system.web>
<pages validaterequest="false">
</pages>
</system.web>
</configuration>

The HTML content can be encoded/decoded using the Server.HtmlEncode(string)/Server.HtmlDecode(string) functions.

How To: Enable Microsoft ASP.NET Ajax Extension V1.0 on an existing site

2007-08-28T13:17:00.000-07:00

The fastest way to add ajax fuctionality to your site -
Here is a good explanation of the process of enabling ajax in an asp.net page.
There is also integeration of CTP on an existing site.

How to delete row in a DataTable with C# or VB.NET

2007-08-28T09:19:00.000-07:00

When you use a DataRow.Delete() method the row is not actually deleted. It is only marked to be deleted after calling DataTable.AcceptChanges(). It is not good idea to remove row with DataTable.Rows.Remove or RemoveAt methods. They forces row removing and causes by iterating the following exception:
'Collection was modified; enumeration operation may not execute'
One more thing to be sure that the iterating will be performed succesfully is to iterate through returned by DataTable.Select() rows (not DataTable.Rows).

For Each row As DataRow In dt.Select()
If (bool_statement) Then
row.Deleted()
Enf IF
Next

dt.AcceptChanges

If adapter is used changes can be commited by Update method. All rows with DataRow.RowState of 'Deleted' will be deleted.

How to use SQL SERVER 2005 with SQL EXPRESS at the same time.

2007-08-22T00:59:00.000-07:00

Error message received by Visual Studio 2005:
"Connections to sql server files (*.mdf) require sql server express 2005 to function properly"
I had installed Visual Studio 2005 and SQL Server 2005 Developer Edition when I received it. To solve the porblem I installed other instance of SQL Server - Express Edition. But to get VS to work with it I had to change its instance name in the VS options. Tools -> Options - > Database Tools -> Data Connections. Now I can work with the two sql server instances - Developer Edition and Express Edition.

To change an existing instance of Microsoft SQL Server 2005 to a different edition of SQL Server 2005, you must run SQL Server 2005 Setup from the command prompt and include the SKUUPGRADE=1 parameter.

Checking for existing Javascript variable

2007-08-21T03:53:00.000-07:00

Somethemes it is necessary to know if the variable is already defined. For example when postback methods which register client script block are used.

function isSet( v )
{
return( typeof( v ) != 'undefined' );
}

Default Web Site on IIS doesn't work until changing the default port.

2007-08-21T02:13:00.001-07:00

It is a very strange problem that occurs sometimes.
"IS Unexpected error 0x8ffe2740"
Today I have just found the reason - Skype is using the default port 80 for alterantive connection.
Resolve that by:
Skype File, Options, Advanced, Connection
Uncheck "Use Port 80 as an alternatives for incoming connections" and restart default website or IIS

How to get random number or generate random password with VB.NET or C#

2007-08-20T23:03:00.000-07:00

The simplest way to get random number is to get instance of the Random class and use the "Next" method.
Dim rand As Random=new Random()
rand.Next() gives you a random nonnegative number
rand.Next(23) gives you a random nonnegative number less than integer value (23 for the example)
rand.Next(23, 89) gives you a random nonnegative number in the specified range

With this class you can generate also double values and bytes.

Here is an way for generating random password using guid.
So simple, so effective.

Public Function GetRandomPassword(ByVal length As Integer) As String
Dim rand As String = System.Guid.NewGuid().ToString()
rand = rand.Replace("-", String.Empty)

If length <= 0 OrElse length > rand.Length Then
Throw New ArgumentException("Length must be between 1 and " & rand.Length)
End If

Return rand.Substring(0, length)
End Function

Fire Default button on enter on an Asp.NET page

2007-08-06T02:36:00.000-07:00

I found two ways to get this to work. By Default the first button in the form is the default button. When you push Enter an fire event of this button occur. Current solution is enough to get Login control on asp.net form to work. Here is the code:

Dim ctl As Control = Login1.FindControl("LoginLinkButton")
If Not (ctl Is Nothing) Then
Login1.Attributes.Add("onKeyPress", "javascript:if (event.keyCode == 13) {__doPostBack('" + ctl.UniqueID + "',''); return false;}")
End If

Fix: return false will break the firing of other buttons. Just to ensure right behaviour.

It works fine for all browsers.
There is one more way to do this but unfortinately it doesn't work with firefox.

Login1.Attributes.Add("onkeypress", String.Format("javascript:return WebForm_FireDefaultButton(event, '{0}')", ctl.ClientID))

How to install PHP on IIS

2007-08-02T08:56:00.001-07:00

PHP installation on IIS 7.0 (Windows VISTA)
I will not explain how to do it, just see this good article:
http://blondr.blogspot.com/2006/11/set-up-iis-7-w-mysql-and-php-5.html
It includes also the settings for MySQL and php session' permission.

PHP installation on IIS 5.1

1) add to path c:\PHP
2) rename php.ini-recomended to php.ini

doc_root = c:\inetpub\wwwroot // for IIS/PWS
doc_root = c:\apache\htdocs // for Apache
extension_dir = "c:\php\ext"
cgi.force_redirect = 0
set browscap to c:\windows\system32\inetsrv\browscap.ini

If you want to use the CGI binary, do the following:

* Under 'Home Directory', 'Virtual Directory', or 'Directory', do the following:
* Change the Execute Permissions to 'Scripts only'
* Click on the 'Configuration' button, and choose the Application Mappings tab. Click Add and set the Executable path to the appropriate CGI file. An example PHP 5 value is: C:\php\php-cgi.exe Supply .php as the extension. Leave 'Method exclusions' blank, and check the 'Script engine' checkbox. Now, click OK a few times.
*

Set up the appropriate security. (This is done in Internet Service Manager), and if your NT Server uses NTFS file system, add execute rights for I_USR_ to the directory that contains php.exe / php-cgi.exe.

To use the ISAPI module, do the following:

* If you don't want to perform HTTP Authentication using PHP, you can (and should) skip this step. Under ISAPI Filters, add a new ISAPI filter. Use PHP as the filter name, and supply a path to the php4isapi.dll / php5isapi.dll.
* Under 'Home Directory', 'Virtual Directory', or 'Directory', do the following:
* Change the Execute Permissions to 'Scripts only'
* Click on the 'Configuration' button, and choose the Application Mappings tab. Click Add and set the Executable path to the appropriate ISAPI DLL. An example PHP 5 value is: C:\php\php5isapi.dll Supply .php as the extension. Leave 'Method exclusions' blank, and check the 'Script engine' checkbox. Now, click OK a few times.
* Stop IIS completely (NET STOP iisadmin)
* Start IIS again (NET START w3svc)
3) add user rights to php directory (IIS user - modify, IUSR_MASNINENAME - read)