How to capture logoff time when user closes browser?

Or

How to end user session when browser closed?

These are some of the frequently asked questions in asp.net forums.

In this post I'll show you how to do this when you're building an ASP.NET web application.

Before we start, one fact:

There is no full-proof technique to catch the browser close event for 100% of time. The trouble lies in the stateless nature of HTTP. The Web server is out of the picture as soon as it finishes sending the page content to the client. After that, all you can rely on is a client side script. Unfortunately, there is no reliable client side event for browser close.

Solution:

The first thing you need to do is create the web service. I've added web service and named it AsynchronousSave.asmx. 

Make this web service accessible from Script, by setting class qualified with the ScriptServiceAttribute attribute... 

Add a method (SaveLogOffTime) marked with [WebMethod] attribute. This method simply accepts UserId as a string variable and writes that value and logoff time to text file. But you can pass as many variables as required. You can then use this information for many purposes.

To end user session, you can just call Session.Abandon() in the above web method.

To enable web service to be called from page’s client side code, add script manager to page. Here i am adding to SessionTest.aspx page

When the user closes the browser, onbeforeunload event fires on the client side. Our final step is adding a java script function to that event, which makes web service calls. The code is simple but effective

My Code

HTML:( SessionTest.aspx )

C#:( SessionTest.aspx.cs )

That’s’ it. Run the application and after browser close, open the text file to see the log off time.

The above code works well in IE 7/8. If you have any questions, leave a comment.

I know there are many posts dedicated to this topic. For example, Sara Ford posted about 290 shortcuts on her blog. Check Zain Naboulsi blog for VS 2010 tips.

But it’s almost impossible to use all of them on daily basis. And further most of them are really not that useful. Here are 10 of my favorite Visual Studio keyboard shortcuts, ones I use most..

1) Double TAB

If you know snippet key name, write and click double Tab.

For example: Write

If

and then click tab key twice to get

if (true)
{
    
}

Similarly write try then click tab key twice to get

try
{

}
catch (Exception)
{
    
    throw;
}

3) CTRL+K and CTRL+D to format code

4) CTRL+SHIFT+V to cycle through clipboard

5) SHIFT+ALT+ENTER for full screen mode

6) F7 to switch between code behind and .aspx files

7) CTRL+H or CTRL+SHIFT+H for find and replace

8) Ctrl+F5 to run without debugging. F5 only will run in debugging mode

    F11 to step into a method. SHIFT+F11 to step out of a method. F10 to step over a method.

9) F9 toggle and un-toggle breakpoints

10)F12 to go to definition

What’s your favorite Visual Studio keyboard shortcut/hidden feature/trick..?

In this article, I will explain how to save Asp.Net page values asynchronously (aka Gmail style of saving mail drafts).  

[System.Web.Script.Services.ScriptService]    
public class AsynchronousSave : System.Web.Services.WebService 

Here is the AsynchronousSave webservice class: 

// To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line. 
[System.Web.Script.Services.ScriptService]
public class WebService2 : System.Web.Services.WebService
{

    [WebMethod]
    public string HelloWorld()
    {

        return "Hello World";

    }

    [WebMethod]
    public string SaveInput(String input)
    {
        string StrInput = Server.HtmlEncode(input); if (!String.IsNullOrEmpty(StrInput))
        {

            string[] strFields = StrInput.Split('+');

            //code to save all input values
            // you can easily savethese values to temp DB table, temp file or xml file
            //Dispaly last saved values

            return String.Format("Last saved text: FirstName {0} ,<br/> Last name {1} <br/> Last "

            + "saved draft {2} at {3}.", strFields[0], strFields[1], strFields[2], DateTime.Now);

        }

        else
        {

            return ""; //if input values are empty..retrun empty string
        }
    }
}

<asp:ScriptManager runat="server" ID="scriptManager">
    <Services>
        <asp:ServiceReference Path="~/AsynchronousSave.asmx" />
    </Services>
</asp:ScriptManager>

<div>
    First Name:<asp:TextBox ID="txtFirstName" runat="server"></asp:TextBox></br> 
    LastName:<asp:TextBox ID="txtLastName" runat="server"></asp:TextBox></br> 
    Draft :<asp:TextBox ID="txtDraft" runat="server"></asp:TextBox></br></div>
<div id="Preview">

<script language ="javascript" >
    //This function calls the web service    
    function SaveUserInput() {
        var fName = document.getElementById("txtFirstName");
        var lName = document.getElementById("txtLastName");
        var draft = document.getElementById("txtDraft");
        //Saving all input in a single value         
        var input = fName.value + "+" + lName.value + "+" + draft.value;
        //ProjName.WebServiceName.WebMethod         
        SampleApplication1.AsynchronousSave.SaveInput(input, SucceededCallback);
    }
    // This is the callback function that processes the Web Service return value.     
    function SucceededCallback(result) {
        var divPreview = document.getElementById("Preview");
        divPreview.innerHTML = result;
    }
    // execute SaveUserInput for every 10 sec, timeout value is in miliseconds
    window.setInterval('SaveUserInput()', 10000); 
    
</script>

AsyncFileUpload is a new ASP.NET AJAX Control (Ajax Control Toolkit (v 3.0.30930) released for .NET 3.5 SP1) that allows you asynchronously upload files to server. You don’t need a separate upload button for this control.  Add the AsyncFileUpload control and a label to the web form for the uploading and displaying messages respectively.  HTML:

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

</asp:ScriptManager> 

<cc1:AsyncFileUpload ID="AsyncFileUpload1" runat="server" CompleteBackColor="White" 

OnUploadedComplete="AsyncFileUpload1_UploadedComplete" OnUploadedFileError="AsyncFileUpload1_UploadedFileError" 

OnClientUploadComplete="Success" OnClientUploadError="Error" /> 

<asp:Label ID="Label1" runat="server"></asp:Label> 

protected void AsyncFileUpload1_UploadedComplete(object sender, AjaxControlToolkit.AsyncFileUploadEventArgs e) 

{ 

 //Fired on the server side when the file successfully uploaded 

   if (AsyncFileUpload1.HasFile) 

   { 

         AsyncFileUpload1.SaveAs(@"C:\Images\" + AsyncFileUpload1.FileName ); 

         Label1.Text = "Received " + AsyncFileUpload1.FileName + " Content Type " + AsyncFileUpload1.PostedFile.ContentType ; 

   } 

 } 

protected void AsyncFileUpload1_UploadedFileError(object sender, AjaxControlToolkit.AsyncFileUploadEventArgs e) 

 { 

 //Fired on the server side when the loaded file is corrupted 

 //Display some error message here 

 } 

Client side events:

OnClientUploadError - The name of a javascript function executed in the client-side if the file uploading failed  

OnClientUploadComplete - The name of a javascript function executed in the client-side on the file uploading completed

function Success() { 

document.getElementById("Label1").innerHTML = "File Uploaded Successfully !!"; 

} 

function Error() { 

document.getElementById("Label1").innerHTML = "File upload failed"; 

} 

We can use  OnClientUploadComplete to clear fileupload control selction,

function Success() { 
document.getElementById ("Label1").innerHTML = "File Uploaded Successfully !!"; 
var fu = document.getElementById("AsyncFileUpload1"); 
document.getElementById("AsyncFileUpload1").innerHTML = fu.innerHTML; 
} 

Reference:  http://www.asp.net/AJAX/AjaxControlToolkit/Samples/AsyncFileUpload/AsyncFileUpload.aspx

One of new feature that was added in Asp.net 3.5  is script globalization and localization. We can display date based on language setting of browser. Here is code snippet of displaying date in local language using script..

[code:c#]

[/code]

Web Site Project is deployed with source code to the server and all compilation takes place at runtime.

Web Application Projects, the code behind classes are compiled to dll. That dll is deployed and at runtime, the compiled code in the dll and the markup is combined to create a class which is used by the server to render output.

Update:

Good post by anthony on this

post by Stephen on this topic

Anonymous types provide a convenient way to encapsulate a set of read-only properties into a single object without having to first explicitly define a type.

 This is an important feature for the LINQ feature that will be integrated into C#. Since anonymous types do not have a named typing, they must be stored in variables declared using the var keyword, telling the C# compiler to use type inference for the variable.

In C# 3.0, you can declare an integer  as –

[code:c#]

var first = 7;

Console.WriteLine("First variable is of type: {0}", first.GetType());

[/code]

It will return”Int32” as DateType, even though we declare it as “var”. So what  is “var”?

from MSDN..

Local variables can be given an inferred "type" of var instead of an explicit type. The var keyword instructs the compiler to infer the type of the variable from the expression on the right side of the initialization statement.

To put it simply "var" is a keyword that results in variable being of the same data type, of the initializer. It works similar to “object” type in older version. But there is great difference between “Object” and “var”. Check following code snippet-

[code:c#]

object newObj = 58;  

int test = newObj; //this line result in an error "Cannot implicitly convert type object to int"

 int test = (int)newObj; // this line will work. But result in boxing..additional overhead

[/code]

So Objects have boxing and unboxing issues. Now consider same instance with “var”- 

[code:c#]

var newObj = 22;

int test = newObj; //no boxing involved. It is type-safe

[/code]

One of the new controls in ASP.NET 3.5 is ListView. It resembles the GridView control, except that it displays data by using user-defined templates instead of row fields.

The ListView control supports the following features:

ü  Support for binding to data source controls such as SqlDataSource, LinqDataSource, and ObjectDataSource.

ü  Customizable appearance through user-defined templates and styles.

ü  Built-in sorting capabilities.

ü  Built-in update and delete capabilities.

ü  Built-in insert capabilities.

ü  Support for paging capabilities by using a DataPager control.

ü  Built-in item selection capabilities.

ü  Programmatic access to the ListView object model to dynamically set properties, handle events, and so on.

ü  Multiple key fields.