Checkbox in Gridview header to select and deselect all rows using JavaScript

I am going to explain how to add checkbox in header template of gridview to select/deselect all rows using javascript or without any postback.

  <asp:TemplateField>
     <HeaderTemplate>
         <asp:CheckBox ID="chkSelectAllOrders" runat="server" onclick="ChkAllOrders(this);" />
     </HeaderTemplate>
     <ItemTemplate>
         <asp:CheckBox ID="ChkOrders" runat="server"></asp:CheckBox>
     </ItemTemplate>
 </asp:TemplateField>

Call this function in gridview header template, checkbox onclick event.

  <script type="text/javascript">
        function ChkAllOrders(Checkbox) {
            var gvHeaderChkbox = document.getElementById("<%=gvOrders.ClientID %>");
            for (i = 1; i < gvHeaderChkbox.rows.length; i++) {
                gvHeaderChkbox.rows[i].cells[0].getElementsByTagName("INPUT")[0].checked = Checkbox.checked;
            }
        }
    </script>

The above javascript function just gets the gridview id in its variable named 'gvHeaderChkbox'. After that a for loop is executed on gridview rows on its length basis. Please note that you must check your checkboxes on basis of cell position in that particular row. If you specify your checkboxes on 'xth' column than it means your cell value will be 'x-1'.

That’s it!!…..Happy Programming...

WHILE Loop With CONTINUE and BREAK Keywords in SQL SERVER

The break command terminates the loop, while continue causes a jump to the next iteration of the loop, skipping all the remaining code in that particular loop cycle.

Example of while Loop without break and continue:-

DECLARE @counter INT
SET @counter = 1
WHILE (@counter <=6)
BEGIN
PRINT @counter
SET @counter = @counter + 1
END
GO

Output:-  1  2  3  4  5  6

Example of while Loop with break:-

DECLARE @counter INT
SET @counter = 1
WHILE (@counter <=6)
BEGIN
PRINT @counter
SET @counter = @counter + 1
IF @counter = 3
BREAK;
END
GO

Output:-  1  2 (Because when counter reach on break command fire and terminate the loop, as i told you in definition)

Example of while Loop with break and continue:-

DECLARE @counter INT
SET @counter = 1
WHILE (@counter <=6)
BEGIN
PRINT @counter
SET @counter = @counter + 1
CONTINUE;
IF @counter = 5
BREAK;
END
GO

Output:-  1  2  3  4  5  6 (if you are thinking output should be 1 2 3 4, you are wrong because in the last example break would never executed. The reason behind that, every time continue  fired which forced to skip all remaining code for that particular cycle)

That’s it!!…..Happy Programming...

BeginUpdate() and EndUpdate() when populating ListView/TreeView in C# ASP.NET

Often a listview control in C# needs to be populated with large amount of data (bulky operations, for example, adding 1000 items). For every item added in the Listview, the control will redraw itself, thus greatly reduce the overall performance.

However, using the two methods BeginUpdate() and EndUpdate() while performing these bulk operations gives significant advantage. A call to BeginUpdate() can be made before adding/deleting/clearing items. This will stop any paint messages being sent or processed. Once the operation is done, the EndUpdate() can then be called.

 

I have logged the time taken of the above code (i.e. adding 1000 items in a ListView for each button click) with and without the BeginUpdate/EndUpdate method calls using a test application.

The use BeginUpdate() and EndUpdate populates the control with a constant duration and much better performance. Amazing, isn't it?

Here's a simple source code example for using this technique with a ListBox:

ListBox1.Items.BeginUpdate;

for i := 1 to 10000 do
    ListBox1.Items.Add('abcd');

ListBox1.Items.EndUpdate;

To give you an idea of the improvement, we timed the code above (your PC may be faster or slower):

without the BeginUpdate/EndUpdate lines: 4.3 seconds...

with BeginUpdate/EndUpdate: 0.1 seconds, that's 43 times faster!

That’s it!!…..Happy Programming...

How to Pass Encoded data in Query String in C# ASP.NET

Solution :-

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

public class encode
{
    public encode()
    {

    }
    public string base64Encode(string data)
    {
        try
        {
            byte[] encData = new byte[data.Length];
            encData = System.Text.Encoding.UTF8.GetBytes(data);
            string encodedData = Convert.ToBase64String(encData);
            return encodedData;
        }
        catch (Exception ex)
        {
            throw new Exception("Error in base64Encode" + ex.Message);
        }
    }
    public string base64Decode(string data)
    {
        try
        {
            System.Text.UTF8Encoding encoder = new System.Text.UTF8Encoding();
            System.Text.Decoder utf8Decode = encoder.GetDecoder();

            byte[] todecode = Convert.FromBase64String(data);
            int charCount = utf8Decode.GetCharCount(todecode, 0, todecode.Length);
            char[] decoded_char = new char[charCount];
            utf8Decode.GetChars(todecode, 0, todecode.Length, decoded_char, 0);
            string result = new String(decoded_char);
            return result;
        }
        catch (Exception ex)
        {
            throw new Exception("Error in base64Decode" + ex.Message);
        }
    }
}

Just Create a class like this..Now call one of these method by just passing any string data, it will also return string data after encode/decode. Now you can pass this data in your query string just like any normal data.Now the question which was raised on our mind, What is base64 Encoding??

It's a textual encoding of binary data where the resultant text has nothing but letters, numbers and the symbols "+", "/" and "=". It's a convenient way to store/transmit binary data over media that is specifically used for textual data.

That’s it!!…..Happy Programming...

How to make Asp.net Textbox Readonly in JavaScript

Solution:

script type="text/javascript">
    function makeReadOnly(){
        var textbox = document.getElementById("txtName");
        textbox.readOnly = "readonly";                          //readOnly is case-sensitive
        }

<body onload=" makeReadOnly ()">
    <form id="form1" runat="server">
    <div>
        <asp:TextBox ID="txtName" runat="server"></asp:TextBox>
    </div>
    </form>
</body>

The reason behind calling makeReadOnly function in body tag is to make textbox readonly when page is loading. You can also make textbox readonly after page load by just calling the makeReadOnly function on any textbox or button control.

That’s it!!…..Happy Programming...

Program to catch and process an error n times in C#

I am going to implement a class which will catch error only once and process an error more than once which would depend on user, it means how many times user want to process that error. In this class 'n' represent how many times you want to process an error. If you want to process an error three times, you just need to change '3' at the place of 'n'.

using System;

class student
{
    public static void Main(String[] args)
    {
        int a = 3;
        int b = 0;
        int result;
        for (int i = 0; i < n; i++)
        {

            try
            {
                result = a / b;
                Console.WriteLine(result);
            }

            catch (Exception ex)
            {
                Console.WriteLine("error is" + ex.Message);
            }

        }
    }
}

That’s it!!…..Happy Programming...