Solving ASP .Net Issues

How to rename SQL Server Database with physical files ( MDF and LDF )

2025-03-11T02:03:00.000-07:00

Even though this is rare but there can be scenarios where you may have to rename the SQL Server database along with the physical database files ( i.e. MDF and LDF )

Check if string is valid JSON - C# ( C sharp - Csharp )

2024-08-06T05:00:00.000-07:00

Please use the following function. If you don't have Newtonsoft installed then you need to add Newtonsoft first. You can do this using Visual Studio 's NuGet package manage from Tools menu.

using Newtonsoft.Json.Linq;

private static bool IsValidJson(string strInput)
{

            try
  {
  if (string.IsNullOrWhiteSpace(strInput))
{
  return false;
}

strInput = strInput.Trim();

  if ((strInput.StartsWith("{") && strInput.EndsWith("}")) || (strInput.StartsWith("[") && strInput.EndsWith("]")))
{
  try
{
  var obj = JToken.Parse(strInput);
  return true;
}
  catch
{
  return false;
}
}
  else
{
  return false;
}
}
  catch
{
  return false;
}
}

json , valid json , string , c# , c # , csharp , c sharp , invalid json

UNIX Time to DateTime - Timestamp to DateTime - C# (C Sharp)

2022-07-22T04:14:00.006-07:00

Unix time is the number of seconds that have elapsed since the 01 January 1970 00:00:00 UTC.

01 January 1970 00:00:00 UTC is called Unix epoch.

Following short and simple (2 liner) C# (CSharp) function will return the DateTime for the provided Unix Time (Timestamp)

public static DateTime UnixTimeToDateTime(long TimeStamp)
{
if (TimeStamp.ToString().Length == 13)
{

//It means the timestamp is in milliseconds and we need seconds.

//So divide by 1000 to get seconds
TimeStamp = TimeStamp / 1000;

}

DateTime UnixEpoch = new DateTime(1970, 1, 1, 0, 0, 0, 0);
return UnixEpoch.AddSeconds(TimeStamp);
}

unix time to datetime, unix time to date, timestamp to datetime, timestamp to date, c#, c sharp, csharp, asp.net, unix epoch, convert unix time to datetime c#, 13 digit, 3 extra dgits

5th, 10th, nth working (business) day from today (or anydate)

2013-07-08T00:05:00.000-07:00

Here is a little piece of code using which you can calculate 5th, 10th or nth (here n can be any number) working (business) day from today (or any given date).
Note that we are assumiung that Saturday and Sunday are weekend, you can change the code if your weekend is not on Saturday, Sunday.
btnCalc is the button on which's click we are calling the function to calculate and lblDate is the label where we are showing the nth working (business) date.

C# (CSharp)

protected void btnCalc_Click(object sender, EventArgs e)

{

//Here I am calculating 10th working (business) day from today. You can replace the parameter 10 with your required number of working (business) day

//Also I am calculating from today, you can give your required Date as parameter as well at the place of DateTime.Now

lblDate.Text = calculateNthWorkingDay(10, DateTime.Now).ToString();

}

public DateTime calculateNthWorkingDay(int n, DateTime pFromDate) //n=Number of working day.

{

int mWorkingDays = 0;

for (int i = 1; i <= n; i++)

{

pFromDate = pFromDate.AddDays(1);

if (!IsWeekEnd(pFromDate))

mWorkingDays++;

else

n++;

}

return pFromDate;

}

public bool IsWeekEnd(DateTime pDateTime)

{

bool isWeekEnd = false;

if ((pDateTime.DayOfWeek == DayOfWeek.Saturday) || (pDateTime.DayOfWeek == DayOfWeek.Sunday))

{

isWeekEnd = true;

}

return isWeekEnd;

}

VB.Net

Protected Sub btnCalc_Click(sender As Object, e As EventArgs)

'Here I am calculating 10th working (business) day from today. You can replace the parameter 10 with your required number of working (business) day

'Also I am calculating from today, you can give your required Date as parameter as well at the place of DateTime.Now

lblDate.Text = calculateNthWorkingDay(10, DateTime.Now).ToString()

End Sub

Public Function calculateNthWorkingDay(n As Integer, pFromDate As DateTime) As DateTime

'n=Number of working day.

Dim mWorkingDays As Integer = 0

For i As Integer = 1 To n

pFromDate = pFromDate.AddDays(1)

If Not IsWeekEnd(pFromDate) Then

mWorkingDays += 1

Else

n += 1

End If

Return pFromDate

End Function

Public Function IsWeekEnd(pDateTime As DateTime) As Boolean

Dim isWeekEnd As Boolean = False

If (pDateTime.DayOfWeek = DayOfWeek.Saturday) OrElse (pDateTime.DayOfWeek = DayOfWeek.Sunday) Then

isWeekEnd1 = True

End If

Return isWeekEnd1

End Function

Datagrid/GridView Paging not working if set(initialize) from codebehind

2013-03-05T01:47:00.000-08:00

Okay, here is another frustrating issue which you may face while using Datagrid or Gridview and you want to set (initialize) paging from code behind.
Your code will looks perfect to you but still paging is not functional.
Your code may look like
C#

gvUsers.DataSource = mDtUsers; //mDtUsers is your datasource.

gvUsers.DataBind();

gvUsers.AllowPaging = true;

gvUsers.PageSize = mPageSize;

gvUsers.CurrentPageIndex = 0;

VB.Net

gvUsers.DataSource = mDtUsers 'mDtUsers is your datasource.

gvUsers.DataBind()

gvUsers.AllowPaging = True

gvUsers.PageSize = mPageSize

gvUsers.CurrentPageIndex = 0

Everything looks fine? Yeh it do but still paging not functional. So whats the solution?

The Solution

Solution is pretty easy and straight forward and in fact you don't have to add any extra line of code, you simply have to change the sequence of statements. That means set (initialize) the paging before the binding of Datagrid/Gridview and everything will be working perfect, it means your code should be like

C#

gvUsers.AllowPaging = true;

gvUsers.PageSize = mPageSize;

gvUsers.CurrentPageIndex = 0;

gvUsers.DataSource = mDtUsers; //mDtUsers is your datasource.

gvUsers.DataBind();

VB.Net

gvUsers.AllowPaging = True

gvUsers.PageSize = mPageSize

gvUsers.CurrentPageIndex = 0

gvUsers.DataSource = mDtUsers 'mDtUsers is your datasource.

gvUsers.DataBind()

Hope this simnply solution will solve your problem.

Happy Coding! :)

jQuery not working in UpdatePanel

2013-03-01T01:55:00.000-08:00

If you are reading this then this means that you are facing the same problem which I faced and the problem is that jQuery functions are not working after any of the event occurred within the Updatepanel.

I mean suppose you are showing and hiding some DIV using jQuery .show() amd .hide(), the DIV resides in an updatepanel where you have another button as well which is a server side button and calls the Server side event using AJAX (update panel), after doing your work of this button you try to show/hide the DIV but you get surprised as the jQuery function is no more being called.

You jQuery code would be like this

$(document).ready(function () {

$("#btnTest").click(function () {

$("#dvTest").show(); //Here you could be having hide/toggle/slideToggle etc etc

});

</script>

Solution

So whats the solution? Solution is very easy and simple. Use your jQuery code as following

$(document).ready(function () {

$('#btnTest').live('click', function () {

$('#dvTest').show(); //Here you could be having hide/toggle/slideToggle etc etc

return false;

});

</script>

Hope your issue is solved?

Happy coding :)

[RESOLVED] Show Hidden Files and Folders not working. Windows XP

2012-12-25T01:56:00.000-08:00

Though the problem and solution is not at all related with ASP.Net but still is an irritating issue.

Okay here is the problem,
(Note that this issue is created normally due to some virus so I am supposing that you have scanned your system with some good Anti Virus with latest virus definitions)

You have to 'Show the hidden files and folders'.
1. You go to Tools -> Folder Options -> View Tab.
2. Then you check the "Show hidden files and folders" options and click Ok (or Apply then Ok).
Now hidden files and folders are supposed to be available but when you check they are still not there.
Frustrated? Yeah obviously. you repeat above two steps several times but each times either you see the option "Do not show hidden files and folders" checked in View Tab or no option checked even you have checked the "Show hidden files and folders" multiple times.
This is really frustrating I know. Anyways here are three methods you should follow in sequence. If you are good at luck the Solution 1 will serve you or then the Solution 2, and if you are not so good at luck then Solution 3 will surely work for you :). Note that even if your problem get solved using Solution 3 then still you will be luck (no matter less).
All the best!

Solution 1:

1. Click Start -> Run
2. Type regedit and click Ok.
3. Find the key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\SHOWALL
4. Look at the "CheckedValue" key in the pane at right This should be a DWORD key. If it is not DWORD key then delete it.
5. If you have deleted the "CheckedValue" at step or "CheckedValue" was not present in right pane then Create a new key called "CheckedValue" as a DWORD with a value of 1 by right clicking in the right pane Else if "CheckedValue" was there with value other than 1 then double click "CheckedValue" and set the value 1.
6. The "DefaultValue" (its DWORD value as well) key should be having value 2 in right pane. If its not having value 2 or is not DWORD then delete and create with value 2 just like you created "CheckedValue" at step 5.
7. Find the key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\NOHIDDEN
its the key adjacent of the key at step 3.
8. Look the values of "CheckedValue" and "DefaultValue", both of these are DWORD and should be having value = 2. If not DWORD or having any value other than 2 then delete or update just like you did at step 5.
9. Close the Registry Editor and check the option "Show hidden files and folders". If its a success then Congratulations! and if its a fail then don't be panic and go to Solution 2.

Solution 2:

1. Click Start -> Run
2. Type regedit and click Ok.
3. Find the key: HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced
4. Check for the key "Hidden" (of type DWORD) in right pane. If its not a DWORD key then delete it.
5. If you have deleted the "Hidden" key or if it was not there then Create a new DWORD value type key by right clicking in Right Pane and set the value =1 else if it was there with any value other than 1 then set it to 1.
6. Close the Registry Editor and Check the "Show hidden files and folders" option. If its a success then Congratulations! and if its a fail then don't be panic and go to Solution 2.

Solution 3:

1. Click Start -> Run
2. Type cmd and click Ok. This will open the Command Prompt (DOS)
3. Type regsvr32 /i browseui.dll then press the Enter key, wait for a confirmation window. (You can type this directly in RUN and can press enter and then can wait for t he confirmation window)
4. Type regsvr32 /i shell32.dll then press the Enter key, wait for a confirmation window. (You can type this directly in RUN and can press enter and then can wait for t he confirmation window)
5. All done. Now check the option "Show hidden files and folders" which should now be working.

If you have followed above steps carefully and your system is Virus free then you must have solved the problem. If problem still exists or you can not any step from above then please comment.

All the best.

[SOLVED] Dropdownlist SelectedIndexChanged (OnSelectedIndexChanged) From GridView

2012-12-04T23:49:00.003-08:00

You may want to implement some functionality on changing index of a drop down list which is provided within a grid for multi records. I too had to do the same and searched over internet for some suitable solution. Though there are more than one solutions but the solution I am providing is most easy of them and requires no tricks.
The Solution
Note the RED BOLD code of HTML view, which means you will have to set EnableViewState="false" for the griview and also you will have to set AutoPostBack="true" for the dropdownlist.

Here is your GridView code (The HTML)

<asp:GridView runat="server" ID="gvTest" Width="50%" AutoGenerateColumns="false" EnableViewState="false">
<Columns>
<asp:BoundField DataField="Gender" HeaderText="Gender" HeaderStyle-HorizontalAlign="Left" />
<asp:TemplateField >
<ItemTemplate>
<asp:DropDownList ID="ddlTest" AutoPostBack="true" runat="server" OnSelectedIndexChanged="ddlTest_SelectedIndexChanged">
<asp:ListItem Value="Male">Male</asp:ListItem>
<asp:ListItem Value="Female">Female</asp:ListItem>
</asp:DropDownList>
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>

And here is Code behind
1. C#

protected void Page_Load(object sender, System.EventArgs e)

{

try {

FillGridView();

} catch (Exception ex) {

Response.Write(ex.Message);

}

private void FillGridView()

{

try {

DataTable dt = new DataTable();

dt.Columns.Add("Gender");

DataRow dr = null;

dr = dt.NewRow();

dr["Gender"] = "I am a ";

dt.Rows.Add(dr);

gvTest.DataSource = dt;

gvTest.DataBind();

} catch (Exception ex) {

Response.Write(ex.Message);

}

protected void ddlTest_SelectedIndexChanged(object sender, System.EventArgs e)

{

try {

Response.Write("You selected " + ((DropDownList)sender).SelectedItem.Value);

} catch (Exception ex) {

Response.Write(ex.Message);

}

2. VB.Net

Protected Sub Page_Load(sender As Object, e As System.EventArgs) Handles Me.Load

Try

FillGridView()

Catch ex As Exception

Response.Write(ex.Message)

End Try

End Sub

Private Sub FillGridView()

Try

Dim dt As New DataTable

dt.Columns.Add("Gender")

Dim dr As DataRow

dr = dt.NewRow

dr("Gender") = "I am a "

dt.Rows.Add(dr)

gvTest.DataSource = dt

gvTest.DataBind()

Catch ex As Exception

Response.Write(ex.Message)

End Try

End Sub

Protected Sub ddlTest_SelectedIndexChanged(sender As Object, e As System.EventArgs)

Try

Response.Write("You selected " & CType(sender, DropDownList).SelectedItem.Value)

Catch ex As Exception

Response.Write(ex.Message)

End Try

End Sub

[SOLVED] Mailbox name not allowed. The server response was: sorry, your mail was administratively denied.

2012-09-12T06:18:00.003-07:00

If your website is hosted at Godaddy.com then you may face this error while using SMTP.

Mailbox name not allowed. The server response was: sorry, your mail was administratively denied. (#5.7.1)

Whats the reason? And he solution.
the only reason of this error is that Godaddy only allows those email addresses in FROM clause which are from same domain.
Suppose your domain is mydomain.com then only those Mails will be sent which are having an Email address in their FROM clause which is from mydomain.com. Its not must that the email address should exist. You can use imaginary mail address like noreply@mydomain.com etc etc. The only restriction is that the email address should be of same domain.

Let us suppose your domain is mydomain.com
C#

MailMessage mMailMessage = new MailMessage(new MailAddress("noreply@mydomain.com", "No Reply"), new MailAddress("anybody@testdomain.com", "Test User"));

mMailMessage.Subject = "Email Subject";

string mEmailBody = "Email Body";

mMailMessage.Body = pEmailBody;

mMailMessage.IsBodyHtml = true;

SmtpClient mSMTPClient = new SmtpClient("relay-hosting.secureserver.net", 25);

mSMTPClient.Send(mMailMessage);

mMailMessage.Dispose();

VB.Net

Dim mMailMessage As MailMessage = New MailMessage(New MailAddress("noreply@mydomain.com", "No Reply"), New MailAddress("anybody@testdomain.com", "Test User"))

mMailMessage.Subject = "Email Subject"

Dim mEmailBody As String = "Email Body"

mMailMessage.Body = pEmailBody

mMailMessage.IsBodyHtml = True

Dim mSMTPClient As SmtpClient = New SmtpClient("relay-hosting.secureserver.net", 25)

mSMTPClient.Send(mMailMessage)

mMailMessage.Dispose()

No mapping specified for the following EntitySet/AssociationSet

2012-08-09T01:12:00.001-07:00

You can get this error when you have generated your Entity Model from a database.
This error means that due to any issue (update/delete etc) the Entity mappings are not same as the Database.

Solution

There can be seen many solutions to this problem over internet but the best solution as far as I know is
1. Double Click the edmx file to open the Entity Model in design view.
2. Press Ctrl A to select all objects within Entity Model.
3. Now press Delete to delete all objects.
4. Again generate your Entity model from Database using "Update Model from Database" option given in context menu (Right Click).
5. All done.

Hope this will help.

Happy Coding :)

Copy Directory without using Directory.Move [SOLVED]

2012-06-06T05:45:00.000-07:00

Following function will copy a directory/folder from one place to another without using Directory.Move.
Q: Why we need following function if Directory.Move is there?
A: Because Directory.Move expires(deletes) the session whenever you use it.

VB

Private Sub CopyDirectory(pSourcePath As String, pDestinationPath As String)

For Each dirPath As String In Directory.GetDirectories(pSourcePath, "*", SearchOption.AllDirectories)

Directory.CreateDirectory(dirPath.Replace(pSourcePath, pDestinationPath))

For Each newPath As String In Directory.GetFiles(pSourcePath, "*.*", SearchOption.AllDirectories)

File.Copy(newPath, newPath.Replace(pSourcePath, pDestinationPath))

End Sub

C#

private void CopyDirectory(string pSourcePath, string pDestinationPath)

{

foreach (string dirPath in Directory.GetDirectories(pSourcePath, "*", SearchOption.AllDirectories)) {

Directory.CreateDirectory(dirPath.Replace(pSourcePath, pDestinationPath));

}

foreach (string newPath in Directory.GetFiles(pSourcePath, "*.*", SearchOption.AllDirectories)) {

File.Copy(newPath, newPath.Replace(pSourcePath, pDestinationPath));

}

Directory.Delete expires the session [SOLVED]

2012-06-05T01:22:00.000-07:00

Yet another frustrating error. That when you delete a directory the session gets expired automatically.
This is a known issue and is actually a default behavior and is defined in following words.
It is the default nature if you are deleting a subdirectory within your application, your app domain will restart. This removes all session data.
How to overcome this issue?
Here are the 3 possible solutions for this issue.

Solution 1:

Make your directory outside application directory.
Here is the explanation how to use the directory which is outside. I got this solution from the given link as well.
http://stackoverflow.com/questions/502743/asp-net-deleting-a-directory-results-in-application-restart

Solution 2:

Don't delete the directory but only delete files in directory and sub directories. This will at least release the memory. Here is my function to Delete all files (and not directories). Simply call it instead of the Directory.Delete Statement.

VB

Private Sub DeleteFiles(pDirectoryPath As String)

For Each mFile In System.IO.Directory.GetFiles(pDirectoryPath)

System.IO.File.Delete(mFile)

For Each mDirectory In System.IO.Directory.GetDirectories(pDirectoryPath)

DeleteFiles(mDirectory)

End Sub

CSharp (C#)

private void DeleteFiles(string pDirectoryPath)

{

foreach (object mFile_loopVariable in System.IO.Directory.GetFiles(pDirectoryPath)) {

mFile = mFile_loopVariable;

System.IO.File.Delete(mFile);

}

foreach (object mDirectory_loopVariable in System.IO.Directory.GetDirectories(pDirectoryPath)) {

mDirectory = mDirectory_loopVariable;

DeleteFiles(mDirectory);

}

I am not stealing the credits for this solution. I got the idea of this from following article and then made my own function with little bit of modifications

http://www.vikramlakhotia.com/Deleting_Directory_in_ASPnet_20.aspx

Solution 3:

This will work for your local system and for dedicated/virtually dedicated hosting and for only those shared hosting which allow you to run your application/website in full trust mode.

You have to add following function in your code and then have to call it before you use the Directory.Delete method.

VB

Private Sub FixAppDomainRestartWhenTouchingFiles()

Dim p As System.Reflection.PropertyInfo = GetType(HttpRuntime).GetProperty("FileChangesMonitor", Reflection.BindingFlags.Public Or Reflection.BindingFlags.NonPublic Or Reflection.BindingFlags.Static)

Dim o As Object = p.GetValue(Nothing, Nothing)

Dim f As System.Reflection.FieldInfo = o.GetType.GetField("_dirMonSubdirs", Reflection.BindingFlags.Instance Or Reflection.BindingFlags.NonPublic Or Reflection.BindingFlags.IgnoreCase)

Dim monitor As Object = f.GetValue(o)

Dim m As System.Reflection.MethodInfo = monitor.GetType.GetMethod("StopMonitoring", Reflection.BindingFlags.Instance Or Reflection.BindingFlags.NonPublic)

m.Invoke(monitor, New Object() {})

End Sub

CSharp (C#)

private void FixAppDomainRestartWhenTouchingFiles()

{

System.Reflection.PropertyInfo p = typeof(HttpRuntime).GetProperty("FileChangesMonitor", System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Static);

object o = p.GetValue(null, null);

System.Reflection.FieldInfo f = o.GetType().GetField("_dirMonSubdirs", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.IgnoreCase);

object monitor = f.GetValue(o);

System.Reflection.MethodInfo m = monitor.GetType().GetMethod("StopMonitoring", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic);

m.Invoke(monitor, new object[]);

}

Again I won't try to steal the credits.
Here is the link from where I got this solution.
http://dotnetslackers.com/Community/blogs/haissam/archive/2008/11/12/disable-session-expiration-when-using-directory-delete.aspx

The version of SQL Server in use does not support datatype 'datetime2' [SOLVED]

2012-06-05T00:24:00.000-07:00

While using the Enitity framework you can come across the following error.
The version of SQL Server in use does not support datatype 'datetime2'
You must have checked your Database tables that if you have set datatype datetime2 for some field and I am sure you didn't find any of such field.
Okay, the problem is with the entity framework and not with the SQL Server.

Here is the Solution
1. Open your EDMX file in XML Editor or any file editor (like notepad).
2. Search for ProviderManifestToken in the file (it should be in top 7-8 lines)
3. It will be having the value 2008 (or may be 2010 in some cases).
4. Change the value from 2008 (or 2010) to 2005.
5. Save the file.
6. Run your code.
7. Hope the issue is not there any more.

a generic error occurred in gdi+ [SOLVED]

2011-12-20T23:10:00.000-08:00

Hello folks,
If you are reading this BLOG post then either you are facing the
"The process cannot access the file because it is being used by another process" error
or the
"a generic error occurred in gdi+" error
while manipulating images in ASP .Net (VB .Net/C#).
The issue may appear due to new Bitmap([IMAGE PATH]) statement

or by the Image.FromFile([IMAGE PATH]) statement in your code where you load the image in your code. This is because GDI+ keeps a lock on files from which an image was contructed. To avoid the lock, construct the image from a MemorySteam. That is
C Sharp (C#)
MemoryStream ms = new MemoryStream(File.ReadAllBytes([IMAGE PATH]));

Image img = Image.FromStream(ms);

VB .Net
Dim ms As MemoryStream = New MemoryStream(File.ReadAllBytes( [IMAGE PATH]))

Dim img As Image = Image.FromStream(ms)

Hope this will solve your issue and you will not receive any of the above errors.

Also don't forget to close and dispose the MemoryStream and Image after the usage else you may get the "Out of memory" error.

Reference:

http://social.msdn.microsoft.com/Forums/en/csharpgeneral/thread/a3a784f2-f901-4748-90e2-dbc7e755aeeb

Gridview and Hidden Cells (Visible ="false")

2011-09-28T00:16:00.000-07:00

This is another frustrating thing developers face while using Gridview instead of the Datagrid. That is when they try to use the value of some hidden cell of Gridview in Code behind they get the empty value. This is obviously very frustrating and have teased me a lot but after Googling and the doing some experiments I got the solution. Whats the solution?
Okay here is the simple solution for this issue
Don't set the Visible property equal to false in design time (HTML code). Instead set visibility to false in RowDataBound event of the Gridview. This will hide the cell but still the value of cell will be available in code behind.
Here is the sample code (let us suppose the Gridview id is gvTest)

VB.Net

Protected Sub gvTest_RowDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles gvTest.RowDataBound

e.Row.Cells(0).Visible = False

End Sub

protected void gvRecruiter_RowDataBound(object sender, System.Web.UI.WebControls.GridViewRowEventArgs e)
{
e.Row.Cells[0].Visible = False;
}

This will make Cells[0] to false but still its value will be available in code behind which will not be empty now.

Maintain scroll position on postback (ASP.net 1.1, 2.0, 3.5, 4.0)

2011-02-21T23:24:00.000-08:00

We often face this issue that our control is placed somewhere down in page and we have reached the control using the scrollbar of browser.

Now there is some postback event associated with that control (that control can be radiobutton, listbox, dropdown list, chekbox, button etc) and when that even is fired the page comes back with its scroll position at top.

Frustrated? Yes obviously its such a situation that now you have to again scroll down to the control.

ASP .Net 2.0 and above

Microsoft (ASP.Net) has provided a very simple and smart solution for this. You just have to set the MaintainScrollPositionOnPostback property is page directive (Top most line of HTML view of aspx page).

Let say your page is default.aspx then following will be the Page directive in order to maintain the scroll position.

<%@ Page Language="VB" AutoEventWireup="false" CodeFile="default.aspx.vb" Inherits="_default" MaintainScrollPositionOnPostback="true" %>

ASP .Net 1.1

For ASP .Net 1.1 you can use following. i.e. smartnavigation attribute in the page directive.

<%@ Page Language="VB" AutoEventWireup="false" CodeFile="default.aspx.vb" Inherits="_default" SmartNavigation="True" %>

Now whenever page will be posted back from some control which is somewhere scrolled down then after postback the position of cursor (control) will be maintained.

Separate Session for multiple Tabs

2011-01-31T22:04:00.000-08:00

With growing usage of Tabbed browsing this can be requirement in some cases that separate sessions should be used for multiple Tabs.
ASP .Net 2.0 (and MAY BE later versions) provide a smart solution for this purpose. The solution is to add following line in your web.config file

<sessionState mode="InProc" cookieless="UseUri"></sessionState>

above line should be added in system.web section of web.config. This will add the session value in URL

Accessing client side updated value at Server side

2010-10-26T04:45:00.000-07:00

Often we use Javascript to update some hidden fields or some dropdown, textbox etc. Its ok and is a quick approach but whats the issue with it?
The only issue we face is that when we try to access the value of such controls at server side we always get the previous value i.e. the value which was there when page was posted last time.
Whats the solution to get the updated value i.e. the value which was updated at client side using Javascript?
Its pretty much easy and straight. You just have to use the Request.Form at server side.

Let us suppose the control name is txtTest and its value is update at client side using Javascript. We will using following statement to get the updated copy.

VB
Dim tmpStr as String = Request.Form("txtTest").Tostring()

C#
String tmpStr = Request.Form["txtTest"].ToString();

Date difference in Javascript

2010-10-20T03:43:00.000-07:00

This can be a need of people that they get instant difference between two dates without the postback. In .Net (C# or VB .Net) its pretty much easy and straight but in Javascript its not that much straight (Though is easy).
Anyways here is the solution. Following is the Javascript function calculating date difference in between two dates (give in two textbox named txtStartDate and txtEndDate) and will store the result (in days) in a textbox named txtDuration.

function calculateDuration()
{
var msInDay = 1000 * 60 * 60 * 24; //Milliseconds in a day
var startDateMS = new Date(document.getElementById("txtStartDate").value).getTime();
var endDateMS = new Date(document.getElementById("txtEndDate").value).getTime();
var differenceMS = Math.abs(endDateMS - startDateMS);
document.getElementById("txtDuration").value = Math.round(differenceMS/msInDay);
}

This function can be called like
<asp:TextBox ID="txtDuration" runat="server" onclick="javascript:calculateDuration();" onfocus="javascript:calculateDuration();"></asp:TextBox>

Validation of viewstate MAC failed

2010-10-14T00:31:00.000-07:00

Yet another very teasing issue ASP .Net developers face. Solution is pretty much simple.

Add following link in your web.config file.

Above line should be included within section.

if you don't want this solution to implemented on project level then you can add these attribute to the page(Top most line of HTML view) directive of the page which is creating issue.

That means you have to add enableEventValidation="false" viewStateEncryptionMode="Never" in page directive.

For a more detail discussion and more solution about the issue please follow the following link

http://blogs.msdn.com/b/tom/archive/2008/03/14/validation-of-viewstate-mac-failed-error.aspx

Disable Next Previous Months (including all dates other than Current Month) in ASP .Net Calendar Control

2010-08-18T22:13:00.000-07:00

Often we need ASP .Net calendar control in our webpages. Most of the times we require navigation in between dates of the calendar control but there can be a requirement that when we want that users should not be able to select dates from month other than the current month.

Some people might be thinking in mind that Microsoft has provided the ShowNextPrevMonth property of a calendar control which can be set to false in order to disable the navigation in between months. Ok, this will disable navigation but what about the dates of adjacent months shown in current month?

Following is the output of a normal Calendar control when ShowNextPrevMonth is not set to false.

Note the red circles in above image. July and September will allow you to navigate through other months and red circles below will allow you to select dates of adjacent months.

Ok now we set the ShowNextPrevMonth property to false and see the output. Following is the output in this case.

So setting out the ShowNextPrevMonth property has disabled the July and September links but dates of adjacent months are still there which can be selected as well. How to disable/hide these? Unfortunately there is no such default property provided using which one can disable or hide these dates but fortunately doing this using code is not a complex task. Use following code and this will hide these dates of adjacent months. We will make use of DayRender event of the Calendar control.

====================================

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

Calendar1.ShowNextPrevMonth = False

End Sub

Protected Sub Calendar1_DayRender(ByVal sender As Object, ByVal e As DayRenderEventArgs) Handles Calendar1.DayRender

If e.Day.IsOtherMonth Then

e.Cell.Text = ""

End If

End Sub

=====================================

Following is the output of above code

You see there are no navigational links (July, September) and also dates of adjacent months have been hidden.

Hope this will solve your issue.

Disable browser back button

2010-08-18T00:45:00.000-07:00

Sometimes we need a functionality that user should not be allowed to go to previous page using the browser back button. Most of us then try to search that how we can disable the browser back button.

A simple and straight answer is that browser's back button can not be disabled because browser resides at user's machine and not on Server. All we can do is to prevent a page for being cached. So if a page is not being cached at client then browser back button will not allow a user to navigate to that page.

What's the procedure?

Procedure is pretty much easy and described in below.

A very important thing to remember is that you have to use this code in page1 in case you want that page1 should not be available using back button of browser. i.e. use this code in that page which you want not available at browser back button.

==================================

Use following 3 lines in HEAD section (HTML view)

use following lines in Page_Load (Code behind)
VB

Response.Cache.SetCacheability(HttpCacheability.NoCache)

Response.Buffer = True

Response.ExpiresAbsolute = DateTime.Now().AddDays(-1)

Response.Expires = 0

Response.CacheControl = "no-cache"

C # (C Sharp)
Response.Cache.SetCacheability(HttpCacheability.NoCache);
Response.Buffer = true;
Response.ExpiresAbsolute = DateTime.Now().AddDays(-1);
Response.Expires = 0;
Response.CacheControl = "no-cache";

==================================

This should solve your issue.

Redirecting Parent page from iframe using same query string

2010-08-11T03:52:00.000-07:00

Once I got caught in a situation that I had to check Database changes from a hidden iframe placed withing a page and then had to redirect the parent page in a way that parent window don't lose its querystring.

Following was the solution which I used.

========================================

In my main page(testpage.aspx) I had following statement for hidden iframe

in refreshpage.aspx I was having nothing but a timer and its tick event which was having the code to check in Database that either some new entry has been made or not. And in case there was any new entry I was refreshing the parent page by using Javascript.

Following is the HTML code for the timer part of my refreshpage.aspx.

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

<asp:Timer ID="Timer1" runat="server" Interval="5000"></asp:Timer>

Remember that scriptmanager is must as I am using Timer of AJAX Extensions.

Following is the VB code for refreshpage.aspx.

Protected Sub Timer1_Tick(ByVal sender As Object, ByVal e As System.EventArgs) Handles Timer1.Tick

If RecordInserted() Then

'RecordInserted is my own function to check if data is enetered or not.

ClientScript.RegisterClientScriptBlock(Me.GetType, "", "<script>window.parent.location.href = ""testpage.aspx?" & Request.QueryString.ToString & """;</script>")

End If

End Sub

====================================

This is it for the code and following is the explanation of above.

refreshpage.aspx checks the database after every 5 seconds that if there is new entry or not and if there is any it refreshes the parent page using Javascript.

<%= Request.QueryString.ToString %> is required in case when QueryString is required for the redirect from iframe.

Hope this will help you :)

IsDate() for C# (C Sharp)

2010-08-03T00:52:00.000-07:00

As we all know that IsDate() is a function of VB .Net which checks that either a provided object is date or not. Naturally we all think that the same function will be there in C# (C Sharp) as well but this is not the case.

Following is a simple IsDate() function for C# (C Sharp) which acts exactly like VB .Net

=====================================

public static bool IsDate(object pDate)

{

DateTime mDate;

if ((pDate != null) && (pDate.ToString().Trim() != ""))

{

return DateTime.TryParse(pDate.ToString(), out mDate);

}

else

{

return false;

}

URL Rewriting (making user Friendly URLs)

2010-07-15T00:29:00.000-07:00

The Problem:

At number of occasions we need a user friendly URL instead of a messy URL having the query string variables.

Like we may be having

URL A: http://www.mywebpage.com/product.aspx?id=123476576

and we want to have a URL for above as

URL B: http://www.mywebpage.com/product_123476576.aspx

Obviously from above two the 2nd one is more user friendly and easily readable. Now the question is how to accomplish this task. Okay solution is not at all a complex solution. In following I will be explaining the solution in detail

The Solution

Though there are more than one ways for this task but I will make use of the method "application_beginrequest" of "Global.asax". This method is called every time some request is made to the website.

Following will be the code to convert URL A into URL B. You can modify this code as per your need.

VB

Public Sub application_beginrequest(ByVal sender As Object, ByVal e As EventArgs)
Try
Dim initialurl As String = Request.Url.ToString
If initialurl.ToLower.IndexOf("product_") >= 0 Then
Dim mTemp As String = initialurl.Substring(initialurl.LastIndexOf("_") + 1)
Dim mProductID As Integer = mTemp.Substring(0, mTemp.LastIndexOf(".aspx"))
Dim mOriginalURL As String = "product.aspx?id=" + mProductID
Context.RewritePath(mOriginalURL)
End If
'Code to Log your Error
Catch ex As Exception
End Try
End Sub

CSharp (C#)

public void application_beginrequest(object sender, EventArgs e)
{
try
{
string initialurl = Request.Url.ToString();
if (initialurl.ToLower().IndexOf("product_") >= 0)
{
string mTemp = initialurl.Substring(initialurl.LastIndexOf("_") + 1);
int mProductID = Convert.ToInt32(mTemp.Substring(0, mTemp.LastIndexOf(".aspx")));
string mOriginalURL = "product.aspx?id=" + mProductID;
Context.RewritePath(mOriginalURL);
}
}
catch (Exception ex)
{
//Code to Log your Error
}
}