Shiran's Blog

Cannot evaluate expression because a thread is stopped at a point where garbage collection is impossible, possibly because the code is optimized.

2011-09-08T11:10:00.000+05:30

Gridview RowEditing checkbox value

2011-02-01T16:32:00.001+05:30

We know if we have manually binds the data then, we can access the checkbox or what ever the control by it's id.
as follows

CheckBox ck = (CheckBox)GridView1.Rows[e.NewEditIndex].Cells[8].FindControl("yourCheckBoxControl");

What if you auto bided the data to a gridview,

CheckBox ck = (CheckBox)GridView1.Rows[e.NewEditIndex].Cells[8].Controls[0];

DropDownList - Set selected value

2011-01-26T23:02:00.001+05:30


The following code snippent shows how to set the selected item of a
DropdownList

DropDownList1.ClearSelection();
ListItem li = DropDownList1.Items.FindByValue("20"); 
DropDownList1.Items.FindByText(li.Text).Selected = true;

I have seen many beginners are struggling to set the selected value  dynamically,
Hope this is very helpful.

The report you requested requires further information

2011-01-16T14:24:00.001+05:30

This issue is a common one who starts working on Crystal Reports with Dataset (.Net)

Ill show a sample code snippet where you can generate this issue.

                 ReportDocument report = new ReportDocument();    

                 BAgent bAgent = new BAgent();
                 DataSet dsStatus = new DataSet();
                 dsStatus = bAgent.GetStatus();

                 string reportPath = Server.MapPath("/Agent/Reports/GetStatusRpt.rpt");  
                 report.Load(reportPath);

                 report.SetDataSource(dsStatus);// this is the line cause for this issue
                CrystalReportViewer1.ReportSource = report;  
                 CrystalReportViewer1.DataBind();  
                 CrystalReportViewer1.RefreshReport();

Here is the solution, use the datset table instead of the dataset

                 ReportDocument report = new ReportDocument();    

                 BAgent bAgent = new BAgent();
                 DataSet dsStatus = new DataSet();
                 dsStatus = bAgent.GetStatus();

                 string reportPath = Server.MapPath("/Agent/Reports/GetStatusRpt.rpt");  
                 report.Load(reportPath);

                 report.SetDataSource(dsStatus.Tables[0]); 
                 CrystalReportViewer1.ReportSource = report;  
                 CrystalReportViewer1.DataBind();  
                 CrystalReportViewer1.RefreshReport();

Hope you got rid from this issue. Enjoy coding.

GridView Hidden Column Data Access

2011-01-13T10:10:00.001+05:30

Again I faced an issue, as usual before .net version 2.0 I set a column's visibility property of a gridview to false.
If you are a developer by now you know why I did that. I know you guessed it. I just wanted to use that column's value
in one of my calculations, and didn't want to show it to the user.

Grid is working fine it hides the column I wanted to hide, I am happy!., Suddenly I realized that I don't get the value from
the hidden (visibility= false) column's cell value in the following method.

 protected void grd_SelectedIndexChanged(object sender, EventArgs e)
 {
      GridViewRow row = grd.SelectedRow;
      string aValue = row.Cells[8].Text; //this is the column I set false visibility
 }

I was looking my coding deeply I am sure this is correct 100%, then what has gone wrong?

With 2.0 and above versions on .Net when you set a column of a gridview to visibility false

it doesn't bind the data to this hidden column. You must be really disappointed hearing this

news, even I did. Wait you don't have to worry so long.

Don't set your column's property visibility to false in the design view. If you do so it will

call before the databind. When there is no column databing is not take place and ignores this hidden column.

Obvious we don't get data (you are lucky only you didn't get the data, worse case this might throw an error)

Trick to overcome this issue,

RowCreated event of a GridView takes place after the data binding, so we can do something like following

code snippet.

 protected void grd_RowCreated(object sender, GridViewRowEventArgs e)
{
       e.Row.Cells[8].Visible = false;
 }

This hides the column, still you can access the cell value,

 protected void grd_SelectedIndexChanged(object sender, EventArgs e)
 {
      GridViewRow row = grd.SelectedRow;
      string aValue = row.Cells[8].Text; //I get the cell value, I am happy!
}

Enjoy working on Gridview control,

ASP.Net Gridview column totals

2011-01-11T20:18:00.001+05:30

Most of the developers use repeater control, in case where they have to show the totals of a list instead gridview control.
This is not that difficult to show the totals on the gridview itself on footer template. I will show the steps how to do this in this post.

Drag and drop a Gridview on your .aspx and bind the data.

eg:

grd.DataSource = ds;
grd.DataBind();

on above code snippet grd is the my Gridview name and ds is my dataset. (you can use any datasource as your convenience)

Set the ShowFooter property to True of the GridView, this will show the footer on the Gridview.

Write the RowDataBound event as follows, you can change the way you want. (in the following scenario I have not showed the declaration of chkAmount and transCharge
decimal type variables, these two are class level varibles)

        protected void grd_RowDataBound(object sender, GridViewRowEventArgs e)
        {
          
            if (e.Row.RowType == DataControlRowType.DataRow)
            {                
                chkAmount += Convert.ToDecimal(DataBinder.Eval(e.Row.DataItem,  "ChkAmount"));
                transCharge += Convert.ToDecimal(DataBinder.Eval(e.Row.DataItem, "TransCharge"));
            }
            else if (e.Row.RowType == DataControlRowType.Footer) // this is the footer identification
            {
                e.Row.Cells[4].Text = "Totals:";
                // display totals on cells (in my case I have selected last 3 columns)
                e.Row.Cells[6].Text = chkAmount.ToString("N2");               
                e.Row.Cells[5].Text = transCharge.ToString("N2");
                
            }           
        }

Hope this is really easier when it comes to show totals on Gridview footer area . Please refer the following image which is the output of my above coding effort.

Rename IIS7 application (Virtual directory)

2010-09-20T09:47:00.007+05:30

This command will rename an existing directory on IIS7,

C:> %systemroot%\system32\inetsrv\appcmd set app "Default Web Site/OldApplicationName" -path:/NewApplicationName

You just have to change OldApplicationName and NewApplicationName as per your requirement.

.NET Entity Data Model template missing

2010-08-03T09:26:00.004+05:30

I may be bit late, but I thought I must give a try on a MVC Architecture Model.
So, as I do always started to write a sort of "Hello World" app. When I try to create the ADO.NET Entity Data Model, I could not find ADO.NET Entity Data Model template.
Is something wrong here? yep, we need to install Microsoft Visual Studio 2008 Service Pack 1 (iso). Here we go I have ADO.NET Entity Data Model template under my Data category.

There is more than one way...

Page load twice

2010-07-28T11:15:00.002+05:30

I know you may have already frustrated of this issue. Even I was really fed up when I came a cross this weird issue. I was facing this issue when I test my web application with Firefox 3.6.6, I did not check with any previous versions (and I found no issues with IE and some other browsers). Believe me it takes a lot of time to cure this. There are many possibilities but mine was a bad CSS practice, you may be wondering how CSS reloads the whole web page.
This was the issue in my CSS code background-image:url(''), having a empty image URL.
I thought reloading the page twice an issue with my coding on page behind, but ultimately it was a CSS issue.

Let me tel me why an empty URL gives such a major issue. Once the page loads the firefox still tries to find the empty URLs so page loads twice but IE just replaces the empty URL with null value.

As I mentioned above this may not the exact cause for your problem but one of the following might cause your issue. Please visit the following URL (http://www.110mb.com/forum/how-to-stop-firefox-dual-pageloads-t27704.0.html) to see more possibilities. Hope this guides you to find the issue.

must be placed inside a form tag with runat=server

2010-07-19T17:16:00.002+05:30

I got to explain the scenario I cameacross this issue, as this might vary for some other scenarios. I got this error when I try to override the PreRender event of the masterpage's
Content Holder (idea was to get the html of that area what evel loding in to that).

ContentPlaceHolder cph = (ContentPlaceHolder)Master.Controls[0].FindControl("master_content_holder");
var sb = new StringBuilder();
var sw = new StringWriter(sb);
var htmlTxtWr = new HtmlTextWriter(sw);
SmtpUtil smtpUtil = new SmtpUtil();
cph.RenderControl(htmlTxtWr);

I got this error exactly on the last line of code. As error message states our all controlls must be inside a form tag with runat = server (note you can't have form tags on child pages, do not try it, it won't work). I did a small dirty work as to fix this issue.
I just overrided the VerifyRenderingInServerForm mehtod on child page. For me it worked properly, as i didn't have any verification to be done on my page. Be carefull before use.

Drop emails in a folder

2010-07-15T22:29:00.001+05:30

Instead sending an email we can configure the web.config to drop the mail in a local folder.
This is a good feature when it come to testing email on your application while developing.

Just add the following on the web.config

   1:     <system.net>

   2:       <mailSettings>

   3:         <smtp deliveryMethod="SpecifiedPickupDirectory">

   4:        <specifiedPickupDirectory pickupDirectoryLocation="C:\testmails\"/>

   5:         </smtp>

   6:       </mailSettings>

   7:      </system.net>

Following code will drop an email in your folder

   1: var smtpClient = new SmtpClient();

   2: var message = new MailMessage("from@from.com", "to@to.com");

   3: message.Subject = "This is the mail subject";

   4: message.Body = "this is the mailm body";

   5: smtpClient.Send(message);

Double click on the file in your C:\testmails\ folder it will open up on outlook
as an email.

Take asp.net web site offline App_Offline.htm

2010-07-08T21:54:00.001+05:30

Do not need to do any setting on ISS, instead just move in an HTMl file named
App_Offline.htm . This will stop responding to any web request but as the response
this file passes until you remove it from the root or rename it.

SQL DATE FORMAT

2010-06-29T13:13:00.004+05:30

You might have comeacross, situations where the date doesn't show the way you want. Hope this table will help you to get sorted out this issue.

DATE FORMATS
Date Format	Query (current date: 12/30/2006)	Show
1	select convert(varchar, getdate(), 1)	12/30/06
2	select convert(varchar, getdate(), 2)	06.12.30
3	select convert(varchar, getdate(), 3)	30/12/06
4	select convert(varchar, getdate(), 4)	30.12.06
5	select convert(varchar, getdate(), 5)	30-12-06
6	select convert(varchar, getdate(), 6)	30 Dec 06
7	select convert(varchar, getdate(), 7)	Dec 30, 06
10	select convert(varchar, getdate(), 10)	12-30-06
11	select convert(varchar, getdate(), 11)	06/12/30
101	select convert(varchar, getdate(), 101)	12/30/2006
102	select convert(varchar, getdate(), 102)	2006.12.30
103	select convert(varchar, getdate(), 103)	30/12/2006
104	select convert(varchar, getdate(), 104)	30.12.2006
105	select convert(varchar, getdate(), 105)	30-12-2006
106	select convert(varchar, getdate(), 106)	30 Dec 2006
107	select convert(varchar, getdate(), 107)	Dec 30, 2006
110	select convert(varchar, getdate(), 110)	12-30-2006
111	select convert(varchar, getdate(), 111)	2006/12/30

SQL Split Function

2010-06-25T10:04:00.001+05:30

I was just trying to do a split in a stored procedure, and found this
link. This is really helpfull comparing with other resources available on the web.

http://sqltutorials.blogspot.com/2007/09/sql-function-split.html

Below is Split Function in SQL

DECLARE @NextString NVARCHAR(40)
DECLARE @Pos INT
DECLARE @NextPos INT
DECLARE @String NVARCHAR(40)
DECLARE @Delimiter NVARCHAR(40)

SET @String ='SQL,TUTORIALS'
SET @Delimiter = ','
SET @String = @String + @Delimiter
SET @Pos = charindex(@Delimiter,@String)

WHILE (@pos <> 0)
BEGIN
SET @NextString = substring(@String,1,@Pos - 1)
SELECT @NextString -- Show Results
SET @String = substring(@String,@pos+1,len(@String))
SET @pos = charindex(@Delimiter,@String)
END

Result
- SQL
- TUTORIALS

Dotnetnuke System.Security.SecurityException: Request for the permission of type 'System.Web.AspNetHostingPermission

2010-05-23T19:43:00.001+05:30

I got this error when I try to install Dotnetnuke 05.04.02 on my computer on Wndows 7 and IIS7. There was no proper solution for this on the web, but I just change the application pool identity to NetworkService and application worked as expected.

Steps :
Go to IIS and select Application Pools.
Select the DNN web pool on right hand pane.
On Actions press Set Application Pool Default link.
Change the Identity under Process Model to NetworkService

Use a Web Proxy for Cross-Domain XMLHttpRequest Calls

2010-05-19T12:57:00.001+05:30

I had an issue when calling web service through AJAX from 3rd party URL.
Here is the solution

http://developer.yahoo.com/javascript/howto-proxy.html

Using JQuery on blogspot

2010-05-07T11:08:00.001+05:30

As I use JQuery these days, I just though how I can use JQuery on my blog.
I tried to do this and found It’s very easy to use it with blogger. Just a few steps
make this possible. You might be wondering where you can place the JQuery file in
blogger. Google has host these file on the following path “http://ajax.googleapis.com/ajax/libs/jquery/”. Just have to select the version you prefer to use.

Just see the following steps.

Step 1:
Add the following code between header tags of your blog’s HTML.

<head>
<script src='http://ajax.googleapis.com/ajax/libs/jquery/1.4/jquery.min.js' type='text/javascript'/>
</head>

Example:

Step 2:
Add the functions in between header tags as follows,

<head>
<script src='http://ajax.googleapis.com/ajax/libs/jquery/1.4/jquery.min.js' type='text/javascript'/>

<script type="text/javascript">
    function MouseOn() {
        $(document).ready(function() {
        $("img").toggleClass("newClass");
            //$("#testPara").append("Shiran the greatest" + count );

        });
    }
</script>
</head>

Example :

Step 3: (Optional)
If there are any CSS involved embed them also in between header tags as follows

<head>
<script src='http://ajax.googleapis.com/ajax/libs/jquery/1.4/jquery.min.js' type='text/javascript'/>

<script type="text/javascript">
    function ChangeCSS() {
        $(document).ready(function() {
             //here this will toggle CSS classes on an event
         $("img").toggleClass("newClass");

        });
    }

<style type="text/css">
.toggler {width: 100px; height: 200px;}

.newClass {width: 500px; height: 866px;}
</style>

</script>
</head>

Need to call the above ChangeCSS() JS function where this need to be done.

Example:
this maight be in post or a HTML/JavaScript gadget

<img class="toggler" src="http://1.bp.blogspot.com/_8fX3E/S-L0RblzI/AAAADtQ/nB8kJYc/s200/108_f0.jpg" onmouseover="ChangeCSS()"/>

Give your visitors a shock.

Enable JQuery intellisense in VS 2008

2010-05-06T18:10:00.001+05:30

I just started to do some JQuery on one of my VS projects. I found that we can have intellisense on VS2008. To make this available I had to do some installations and follow few steps to get intellisense on VS2008, I hope these would helpful you as well in projects.

Step 1:
Install VS 2008 SP1, you can get it here

Step2:
Install VS 2008 Patch KB958502, you can get it here

Step3:
Download JQuery js file and JQuery vsdoc.js, both these should be one version
Eg: jquery-1.4.1-vsdoc.js and jquery-1.4.1.js (version may be differ on the version you have downloaded).
Put both files in the same place in your project.

now you are ready to use. You will get intellisense and auto complete features on VS2009

using statement in C#

2010-04-27T13:13:00.001+05:30

This is a nice little statement which reduces our coding and minimises prone to errors.
There are many situations we have to Dispose the object we created. Example

string connString = "Data Source=localhost;Integrated Security=SSPI;Initial Catalog=MyDB;";

SqlConnection myConnect = new SqlConnection(connString);            
SqlCommand cmd = myConnect.CreateCommand();
cmd.CommandText = "SELECT * FROM MyTable";

myConnect.Open();

SqlDataReader dr = cmd.ExecuteReader();

while (dr.Read())
{
    Console.WriteLine("{0}\t{1}", dr.GetString(0), dr.GetString(1));
}

dr.Dispose();
myConnect.Close();
myConnect.Dispose();

Here on above example I just try to connect to a database and take out all records from MyTable.

I have created a SqlConnection object named myConnect and a SqlDataReader object named dr, at the very bottom of the code snippet I have disposed those two objects using Dispose() method.

What will happen if I forget to dispose these objects? memory issues, using statement is a remedy for this and its makes code more readable, robust and clean. I will recode the above code snippet with using “using ” statement.

using (SqlConnection myConnect = new SqlConnection(connString))
{
    SqlCommand cmd = myConnect.CreateCommand();
    cmd.CommandText = "SELECT * FROM MyTable";

    myConnect.Open();

    using (SqlDataReader dr = cmd.ExecuteReader())
    {

        while (dr.Read())
        {
            Console.WriteLine("{0}\t{1}", dr.GetString(0), dr.GetString(1));
        }
    }
}

Don’t you feel more comfortable with using statement? Let me just go bit deep on using statement, how does this work? Actually when an using statement compiled, the CLR converts it to a try and Finally block. It does three things, get the resources (SqlConnection ), encloses in a try block and disposes in the Finally block. Hope you enjoyed …………….

Referring to another config file in web.config file

2010-04-21T11:14:00.001+05:30

Instead of having all connection string detail on web.config file , we can create a new configuration
whatEvernName.config eg(connectionString.config) and have all connection string details in this new .config file.

Please go through the code below to understand this.

web.config
<connectionStrings configSource="connectionString.config" />

connectionString.config
<connectionStrings>
<clear />
<add name="myConnection" connectionString="myConnectionString" providerName="System.Data.SqlClient" /> </connectionStrings>

This is really nice feature when you have a lot of tags in your web.config file,
as it increases the readability. There is another cool feature which is very useful for
developers when it’s come to development or rather I would say debug the code.
Most of the times we have our connection string in one file and there is a high chance to forget
to change live connection string properties to test environment properties, I have made such a mistake and had to restore a latest database backup, but luckily there was not any data lost.

This cool feature avoids taking place such a bad mistake. Try this it’s is really nice and you do not have to keep on changing your web.config’s conection string values. As in above code snippet you can have two config files as connectionString.debug.config and connectionString.releaase.config

VS IDE will take the valuse depending on what you have selected, debug or release. Isn’t it cool.
Enjoy…

GridView column text wrap width

2010-04-20T17:09:00.001+05:30

We had a grid view and one of the column data was dynamically bound. Most of the time this grid goes out of the sreen area and makes user to scroll to right, because of this dynamically bounded column's text lenght. There were some solutions on the web but none of them working properly. Solution is, put the text inside a paragraph tag “<p> your text here</p>”

Rules to Better Websites Navigation

2010-04-09T05:46:00.003+05:30

These rules I found while I am going through Scott Guthrie's web blog. It's captioned as "Adam Cogan's Rules for Better WebSites" and this was written in September 2003, pretty old but still apply.

http://www.ssw.com.au/ssw/Standards/Rules/RulesToBetterWebsitesNavigation.aspx#underline

Scott Guthie's web blog http://weblogs.asp.net/Scottgu/

Visual Studio 2010 Beta 2

2010-02-10T22:52:00.002+05:30

Hi All,
This is what microsoft says, why don't you take this precious chance..........

"Now you can with
Visual Studio 2010 Beta 2 Jumpstart your next project with Visual Studio 2010 Beta 2. The "Go Live" license with this release means you can develop and deploy before the finished product hits the shelf."

Here is the URL http://www.microsoft.com/visualstudio/en-us/products/2010/default.mspx

Microsoft Visual Studio 2005 with Microsoft SQL Server 2008 Support

2009-10-29T17:25:00.002+05:30

I had an issue connecting to sql server 2008 database
in a VS 2005 application, I used .xsd (datase) to
manipulate data. I got an error,

I hope the fix would be helpfull to you as well, download and
install, Studio 2005 Service Pack 1 Update for Microsoft SQL Server 2008 Support

http://www.microsoft.com/downloads/details.aspx?FamilyID=e1109aef-1aa2-408d-aa0f-9df094f993bf&displaylang=en

How do I get the return value and dataset when calling a stored procedure in a typed DataSet object?

2009-10-22T07:04:00.004+05:30

There is no direct way to retrieve the returning value from a stored procedure in typed DataSet object. To accomplish this what you have to do is just add a new method in the partial class of the generated table adapter. Ill show how to do this step by step.

Consider the following stored procedure, which returns a dataset plus a return value. (not a complicated SP). In this case I just return 0 from the SP.

CREATE PROCEDURE [dbo].[GetUser]
@EmailID VARCHAR (100)
AS
BEGIN
SELECT
[UserID],
[FirstName],
[LastName],
[Phone]
FROM
[dbo].[User]
WHERE
[EmailID] = @EmailID

RETURN 0
END

Now add the method following method in the partial class of the generated table adapter. In my case it's UserTableAdapter.

 partial class UserTableAdapter
 {
     public object GetReturnValue(int commandIndex)
     {
            return this.CommandCollection[commandIndex].Parameters[0].Value;
     }
 }

Ok, now you can retrieve the return value plus the dataset,

private DSTableAdapters.UserTableAdapter _userAdapter = null;

protected DSTableAdapters.UserTableAdapter Adapter{
     get{
         if (_userAdapter == null)
           _userAdapter = new DSTableAdapters.UserTableAdapter();
               return _userAdapter;
           }
        }

This is the method that retrieve dataset and the get return value by calling the method (GetReturnValue(int commandIndex) ) we added in to generated partial class

public int GetUser(string emailid)
{
    int success ;
    try
    {

        DS.UserDataTable userDataTable = Adapter.GetUser(emailid);
        if (userDataTable.Rows.Count > 0)
        {
           //assingning to variables
            FirstName = userDataTable.Rows[0]["FirstName"].ToString();
            LastName = userDataTable.Rows[0]["LastName"].ToString();
            success = int.Parse(Adapter.GetReturnValue(0).ToString());
        }   
    }
    catch (Exception ex)
    {
        //write you exception handling
    }

    return success;

Limiting Textarea length

2009-10-14T15:59:00.002+05:30

I just wrote a java script to limit the max length of a teaxtarea control.
Here is the code snippet.

Limiting Textarea length

<'textarea name="txaDescription" onkeypress="return maxLength(this, 250);" textarea>

and the javascript

function imposeMaxLength(Object, MaxLen)
{
return (Object.value.length <= MaxLen);
}

Javascript optional parameters

2009-09-25T14:19:00.001+05:30

Numeric only , windows programing , C#.Net

2009-09-09T21:42:00.002+05:30

If you want to restrict a text box, to enter only numeric values.
Just do the following in the KeyPress event.

private void txtOpenCount_KeyPress(object sender, KeyPressEventArgs e)
{
string str = "\b0123456789";
e.Handled = !(str.Contains(e.KeyChar.ToString()));
}

inputbox in C#

2009-08-23T18:23:00.003+05:30

I had to do a windows program, which is not that familier to me with .Net technology as I am ASP.Net guy. But it was really interesting than I thought before start the developments. In my early carrier I have done lot of developments using VB6.0 and in present too.
I wanted to add a input box in my new windows program which is in C#.Net, suddenly I realised that there is no input dialog box with C#.Net but I found a link to do a input dialog box, which was really helpfull. I think it would be really helpfull you guys as well.

http://www.knowdotnet.com/articles/inputbox.html

SQL LIKE THAN YOU LIKE

2009-08-12T16:22:00.002+05:30

Do not confuse with the title, let me explain what it is. Consider about the following table, (Persons)

One might need to get only the FirstName that starts with letter ‘W’
in this case we can write our query as follows

SELECT * FROM Persons WHERE FirstName LIKE 'W%'

Result would be

OK cool , what if you need to get all the records that FirstName starts
with letter ‘W’ and letter ‘R’, in this case I am sure most of developes
query would be as follows.

SELECT * FROM Persons WHERE FirstName LIKE 'W%' OR FirstName LIKE 'R%'

Fine, you got the result what you expected but there is another way to do this
without using OR FirstName LIKE ‘R%’

SELECT * FROM Persons WHERE FirstName LIKE '[WR]%'

Don’t you think this is better? Keep in mind you can use this not only for the first letter
you can use this for last letter even you can use with negation ( LIKE ‘[^WR]%’)

Get percentage of records from a table

2009-08-11T14:27:00.001+05:30

Have you ever come across a situation where you need to get top 25%
records from a table. Here is the SQL that returns first 25% of records from a table.

SELECT TOP 25 PERCENT *
FROM dbo.yourtable

This will return what you want, the 25% of records from the table. What if you want the second 25% of records.

SELECT TOP 50 PERCENT *
FROM ( SELECT TOP 50 PERCENT *
FROM dbo.yourtable) results ORDER BY 1 DESC

On the above query by descending the records by first column, assuming that it is the primerykey or the records we need to filter by, you will get the top 25% which is the second 25% of the records.

Think how to get the third and the last 25% records leisurely.

ConnectionStringBuilders

2009-08-06T17:14:00.003+05:30

Connection string is a string variable which include many properties and values (InitialCatelog, uid, pwd , Data Source) needs to connect to a database.

SqlConnection cn = new SqlConnection();
cn.ConnectionString ="uid=sa;pwd=Initial Catalog=ADO; Data Source=(local); ConnectTimeout = 30";
cn.Open();

Creating connection string is bit tedious as it’s a string and could be error prone.

ADO.Net providers support connection string builder objects which allow you to create connection string , and establish the name/value pairs using strongly typed properties.

SqlConnectionStringBuilder cnStrBuilder = new SqlConnectionStringBuilder();
cnStrBuilder.UserID = "sa";
cnStrBuilder.Password = "";
cnStrBuilder.InitialCatalog = "ADO";
cnStrBuilder.DataSource = "(local)";
cnStrBuilder.ConnectTimeout = 30;
SqlConnection cn = new SqlConnection();
cn.ConnectionString = cnStrBuilder.ConnectionString;

Here on above example , creates a SqlConnectionStringBuilder variable and passing values for
ConnectionStringBuilder properties and then the ConnectionStringBuilder’s ConnectionString value been assigned to cn.ConnectionString instead directly passing ConnectionString string
as follows.

cn.ConnectionString ="uid=sa;pwd=Initial Catalog=ADO; Data Source=(local); ";

C# File.WriteAllText, File.ReadAllText & File.WriteAllLines

2009-08-04T12:17:00.003+05:30

Technorati Tags: C# File.WriteAllText,C# File.ReadAllText,C# File.WriteAllLines

Most of the times as developers we have to work with text files, as it’s a very simple way to store some data. There are very valuable methods available in File class that we are not using most often.

Look at the following example which writes a formatted string to a text file with new lines.
This is more readable than WriteLine() method. If you use WriteLine() Method then you will have to write line by line most probably you may have to use a loop.

protected void btnTextManipulation_Click(objectsender, EventArgs e)
{
       //gets the file path
      stringfilePath = Server.MapPath("Files/test.txt");
       StringBuilder content = new StringBuilder();

       //note the end of this line i.e \r\n this says enter a new line
      content.Append("This is the first line. \r\n");
       content.Append("This is the secont line. \r\n");

       //Environment.NewLine this says enter a new line too
      content.Append("This is the last line."+ Environment.NewLine);
     
       //Writes to test.txt
      WriteText(filePath, content.ToString());

       //reads from test.txt and asssing to a variable
      stringreadTxt = ReadText(filePath);

       filePath = Server.MapPath("Files/test2.txt");
       //Writes to test2.txt
      WriteText(filePath, readTxt);
}
 
public void WriteText(stringpath, stringcontent)
{
       //this file method writes all test you pass
      File.WriteAllText(path, content);
}

public string ReadText(stringpath)
{
       //this file method reads whole content of the text file.
      returnFile.ReadAllText(path);
}

I will show another example which writes array items in new lines.In the following example WriteAllines() method writesall the items in an array as a new line. With using WriteAllLines() method you can avoid a loop, hich needs to loop through the array and WriteLine to the text file.

protected void btnTextManipulation_Click1(object sender, EventArgs e)
{
   //get the file path
   string filePath = Server.MapPath("Files/test.txt");
   //declare and assign a string array
       string[] content = { "This is the first line.", "his is the secont line.", "This is the last line." };
       WriteArrayText(filePath, content);
}

public void WriteArrayText(string path, string[] content)
{
  //this file method writes all test you pass
  File.WriteAllLines(path, content);
}

Enable session state on a Web Methods, Web service

2009-07-31T14:05:00.007+05:30

By default each web method session state is disabled.
Example:

Declare and assign a session variable in Global.asax Session_Start.

void Session_Start(objectsender, EventArgs e)
{
Session["Overhead"] = 3;
}

Access this session variable (Session["Overhead"] ) in Add Web Method.

[WebMethod(Description = "adds x , y and Overhead session")]
public int Add(int x, int y)
{
   return (x + y) + (int)Session["Overhead"] ;
}

This will not work and throws an error. To avoid this needs to enable session state in each web metods.

Example:

[WebMethod(EnableSession = true, Description = "adds x , y and Overhead session")]
public int Add(int x, int y)
{
return(x + y) + (int)Session["Overhead"] ;
}

In this above example in the [WebMethod] attribute EnableSession property has explicitily set to true. Now the Add web method is retrieving Session["Overhead"] variable’s value. All you have to do is just enable the session in [WebMethod] attribute.

WebService Method Overloading

2009-07-30T18:32:00.004+05:30

Thursday, July 30, 2009

WebService Method Overloading

First of all what is method overloading ?
Method means having more than one method with the same name but different signature is the simple definition.
Example:

private int Add(int x, int y)
{
    return x + y;
}

private int Add(int x)
{
    return x + 3;
}

private float Add(float x, float y)
{
    return x + y;
}

Above three methods have the same name but different signature.
The following table shows the signature difference among Add methods.

Though method overloading allowed in .Net, it's not allowed in web services as to comply with a rule (WSI BP 1.1 is that each method within a WSDL document must be unique), This clearly emphasis on method overloading. But by using [WebMethod] attribute we can use method overloading. With [WebMethod] pass the MessageName then web service uniquely identifies the overloaded methods.

Example:

[WebMethod(Description = "Adds two integers.",MessageName = "AddInts")]
private int Add(int x, int y)
{
    return x + y;
}

[WebMethod(Description = "Adds 3 on an int value.",MessageName "AddThree")]
private int Add(int x)
{
    return x + 3;
}

[WebMethod(Description = "Adds two floats.", MessageName = "AddFloats")]
private float Add(float x, float y)
{
    return x + y;
}

Here on above three Add methods have unique MessageName as to allow method overloading in web services

VS2010 Beta C# 4.0 Optional parameters, named arguments A feature I was waiting for..

2009-07-28T16:15:00.013+05:30

I was a VB 6.0 developer and I still doing some vb6.0 coding. I often use optional arguments(parameters) with vb6.0, which makes my life easy most of the times.

What is an optional argument?
Arguments must be provided when calling a method if it is not an optional parameter, but can omit arguments for optional parameters.

Example:
VB6.0

Public Function PurchaseOrder(ByVal vPurOrdNo As String, Optional vNotes As Variant)
''Coding....
End Function

on the above example PurchaseOrder function can be called in both ways as follows,

call PurchaseOrder("2010", "passing value to optional argument")
or
call PurchaseOrder("2010")

I was wondering why Microsoft dosn't introduce this feture in visual c# as it's provide such a richness for the language. I heard a good news, .Net 4.0 framework has this feture with named arguments.

* Each optional parameter has a default value as part of its definition
* If argument not passed for optional parameter then the default value will be used.
* Optional parameters must be declared after all the normal parameters (most right side)

Here is the above example PurchaseOrder method is C#

public class OptionalArgumentExample
{
static void Main(string[] args)
{
// Instance anExample does not send an argument for the constructor's
// optional parameter.

PurchaseOrder("2010", "passing value to optional argument");
PurchaseOrder(("2010");
}

// optional parameters needs to be defined with default values. in this
// example "notes" paramete has a default value, so the here the "notes"
//parametes is optional.
public void PurchaseOrder(string purordno, string notes= "default string")
{
//coding here..
}
}

What is a named argument?
Named arguments allows you to pass an argument for a parameter with the parameter's name rather than with the parameter's position in the parameter list.
Example:
C# .Net4.0
public class NameArgumentExample
{

static void Main(string[] args)
{
// Calling normal way
Console.WriteLine(CalculateInterest(5000, 10));

// passing with named arguments any order
Console.WriteLine(CalculateInterest(capitol: 5000, interestRate: 10));
Console.WriteLine(CalculateInterest(interestRate: 10, capitol: 5000));

}

static int CalculateInterest(int capitol, int interestRate)
{
return (( capitol / 100) * interestRate );
}
}

Rare validation

2009-07-20T23:21:00.000+05:30

It's very rare get a chance to validate a check box, I got it today. VS doesn't have a
validation control to achieve this but www.asp.net has recommended a validation
control i.e CheckValidator which is a .dll (AT.Web.UI.Validators.dll
) and can be added to the tool panel. I added this to my validation controls section .
Can be used as normal validation control to validate checkboxes and radio boxes.

<"asp:checkbox ID="chkAgreement" runat="server" Text="I have read the agreement" /">
<"asp:Button ID="btnSubmit" runat="server" Style="z-index: 100; left: 129px; position: absolute; top: 77px" Text="Submit" /">

<"at:CheckValidator ID="_checkValidator" runat="server" ControlToValidate="chkAgreement" Text="Please accept the agreement" style="z-index: 102; left: 15px; position: absolute; top: 47px"">
<"/at:CheckValidator">

A personal belief

2009-07-20T18:25:00.000+05:30

I personally believe as a Sri Lankan, Mr Bandaranayake is the bad ever governor
in Sri Lanka. I personally believe we are not yet independent though Mr. Bandaranayake
spelled it several times. As declaring Sinhalese as the official language he created a gap between poor and rich, conflict between Tamils and Sinhalese and a opportunity to learn English which could have bring most success to our country,

Watch this video and feel free to comment my personal vision.

http://www.youtube.com/watch?v=rbL5E5naR6s

Session variable lifetime

2009-07-16T14:06:00.001+05:30

Before I talk about session variable's life time, Ill just brief why a session variable comes in to play with a web application.

A session is a mechanism to maintain state on a web application, as HTTP protocol is a stateless protocol. What does it means by stateless? this protocol (HTTP) serves as the request comes and destroys all the data (information) on a request. Pages are destroyed and recreated with each round trip to server. Session variables comes in to play when there is a requirement to maintain the state of a web application. Do not misunderstand that session is not the only mechanism to available to maintain state of a web application. Ok, will get back to the topic.

On an ASP.Net application session variable's expiry time decides the life time of a Session
set in the web.config configuration section under
Example:

< sessionState mode="InProc" timeout="20" >

In the above example the timeout = "20" sets the
expiry time of session variables to 20 minutes.

A tip to avoid SQL injection

2009-07-14T17:31:00.000+05:30

System.Data.SqlClient.SqlCommand cmd = new System.Data.SqlClient.SqlCommand(
"select * from Orders where OrderID= '" + passOrderID + "'";

An user can pass anything to passOrderID , this leads a hacker to easily replace
string with something malicious. As shown in the above bad example do not build
dynamic strings, instead use parameters. Anything passed to a parameter considered
as field data and not as part of SQL statement, This avoids above malicious scenario.

Following code snippet demos a parametrized querying steps,
                      

//define SQLCommand object
System.Data.SqlClient.SqlCommand cmd = new System.Data.SqlClient.SqlCommand(
"select * from Orders where OrderID= @OrderID", conn);

//define parameters used in SQLCommand object
SqlParameter para  = new SqlParameter();
para.ParameterName = "@OrderID";
para.Value = passOrderID;

// add parameter to SQLCommand object
cmd.Parameters.Add(para);

or in one line

cmd.Parameters.Add(new SqlParameter("@OrderID",passOrderID));

This makes the application more secure.

Early and Late Binding

2009-07-13T06:42:00.000+05:30

Declaring an variable with specific object type called Early Binding.
Example:

'  Create a variable to hold a new object of type File Stream.
Dim fs As System.IO.FileStream

Declaring an variable with type object called Late Binding,
later this variable can hold any object type.

'  Create a variable to hold a new object 
Dim anyObject As Object
or
Dim fs

'  Later you can assign any object type to this variable
anyObject = CreateObject("Excel.Application")
or you can use the anyObject to hold any other your object type
anyObject = CreateObject("Define.Start")

maintain scrollposition after post back?

2009-07-10T12:54:00.000+05:30

By default a web page will be returned to the top of the page, after a postback. What if you want to take back to the position where user was before the postback , it's simple. You can do one of the followings.

1.For the whole website
In the web.config add the attribute to the pages node.
<"pages maintainScrollPositionOnPostBack="true">

2. Particular page,
In the HTML (.ASPX)
< %@ Page Language="C#" MaintainScrollPositionOnPostback = "true"

and you can set this in

3.CODE (ASPX.SC)
Page.MaintainScrollPositionOnPostBack = true;

That's all you have to do. You will be back to where you were.

static Vs instance methods

2009-06-10T12:38:00.000+05:30

Perfomance , instance methods are not virtual by default but can be declared as virtual. Virtual method has slightly high overhead than a non virtual method. Static methods are not virtual.
So there might be a slight performance issue and this can be ignored as it's not make much impact on performance.

Choosing your method to be static or instance will depend upon the design. If the method going to be used as an object then it should be an instance method. If it doesn't depend on an instance of an object, it should be static. Static methods belong to a type and instance methods belong to instance of a type.

example

Public Class Car
{
// this is a static method
public static void staticMethod()
{
//your code
}

// this is an instance method
public void instanceMethod()
{
//your code
}
}

Accessing static method
Car.staticMethod();

Accessing instance method
Car car = new Car();
car.instanceMethod();

Deployment Project - Cannot open the file 'ASPNETCOMPILER'

2009-06-03T12:23:00.000+05:30

I got this error when I try to deploy an asp.net web site.
"Cannot open the file 'ASPNETCOMPILER'. The document cannot be opened. It has been renamed,deleted or removed".

The solution is, take your deployment project folder out from the site folder (root).
For example : if your project path is "D:\Projects\Ads" then have the deployment folder in "D:\Projects\Deployment". Don't have the deployment folder in site's folder itself as "D:\Projects\Ads\Deployment".

32-Bit application on 64-Bit server with IIS7

2009-06-01T15:35:00.000+05:30

Guys, I had to configure a website which is 32 bit, on a 64 bit server with IIS 7. As you know 64 bit servers doesn’t support 32 bit applications but lucky me, IIS has a feature to enable this

It's so easy. In IIs go to Application Pool Right click on your web site and then go to "Advance Settings" , You will get a property called "Enable 32-Bit Applications" change its value to "True". That's all you have to do .

Scared on OOP.....

2009-05-30T06:12:00.000+05:30

Hay guys, You might be thinking why I am back on my blog after a long time. It's simply b'cause the encourage I got from one of my friends called Gogula and I use to call him gogus most of the time. Thanks man. Ok, here I start it again with OOP & C# .

Before I start anything on this topic let me explain what is an object.

What is an object?

Ha, that could be anything around you in real world. For example your CPU.

What we should consider of an object as a programmer? It's state and the behavior.
I wil just take a scenario that would helpfull you to understand as a programmer, what is an object?. If you were asked to develop a student enrolment application what would you conside as your objects in this application. I will point two objects Student and the Course but there are many more, I will leave you to point after reading this blog.

As I have mentioned above we bothered about state and the behavior of an object.
An object's state is the data and information it contains. For example, If you have a CPU object, it's state could be RAM speed and hard disck capacity. An object's bahavior represeted by it's methods. For example, in your CPU object play movie could be a method.

There are three underline concepts
Encapsulation
Inheritance
Polymorphism

Encapsulation

Encapsulation is a process of binding both data and methods together inside of an object.
Protection and information hiding are techniques used to accomplish encapsulation of an
object. Conside the following Class.

public class Box{
public Box()
{
}

protected double height;
protected double width;
protected double length;

public double GetVolume()
{
double volume = height*width*length;

if(volume<0)>

return volume;
}

}

Classic ASP debugging

2007-03-12T13:37:00.001+05:30

I was frustrated searching for ASP Classic debugger, eventually I found a stady way to do that...Open you ears widly.............

use <'% stop %''>it will break the execution on the stop statement and u can debug in VSInterDev.

Classic ASP debugging

2007-03-12T13:37:00.000+05:30

I was frustrated searching for ASP Classic debugger, eventually I found a stady way to do that...Open you ears widly.............

"<%Stop%>" this will do the magic
... <% stop %>it will break the execution on the stop statement and u can debug in VSInterDev.

CSS

2006-11-04T10:37:00.001+05:30

I have been thinking about what are the best CSS practices. I got this from one of my friend. I’ll open it up to everyone for share it.

Build and test your CSS in the most advanced browser available before testing in others, not after.
If you build a site testing in a broken browser, your code begins relying on the broken rendering of that browser. When it comes time to test in a more standards-compliant browser, you will be frustrated when that browser renders it improperly. Instead, start from perfection and then hack for the less able browsers. Your code will be more standards-compliant from the start, and you won’t have to hack as much to support other browsers. Today, this means Mozilla, Safari, or Opera.
Don’t use quotation marks around paths/URLs.
When setting a background image, or loading in an imported file, resist the urge to surround the path with quote marks. They’re not necessary, and IE5/Mac will choke.
Try to avoid applying padding/borders and a fixed width to an element.
IE5 gets the box model wrong, which really makes a mess of things. There are ways around this, but it’s best to side-step the issue by applying the padding to the parent element instead of the child that gets a fixed-width.
Combine selectors.
Keeping your CSS light is important to minimize download times; as much as possible, group selectors, rely on inheritance, and reduce redundancy by using shorthand.