Today i am explaining here how to drag and drop rows from source gridview to destination gridview in Asp.Net using jQuery UI sortable plugin.

HTML Markup

The HTML markup is simple and it contains two ASP.Net GridViews gvSource is the source GridView and the other gvDest is the Destination GridView.

<asp:GridView ID="gvSource" runat="server" CssClass="drag_drop_grid GridSrc" AutoGenerateColumns="false">

    <Columns>

        <asp:BoundField DataField="Item" HeaderText="Item"/>

        <asp:BoundField DataField="Price" HeaderText="Price"/>

    </Columns>

</asp:GridView>

<hr />

<asp:GridView ID="gvDest" runat="server" CssClass="drag_drop_grid GridDest" AutoGenerateColumns="false">

    <Columns>

        <asp:BoundField DataField="Item" HeaderText="Item" />

        <asp:BoundField DataField="Price" HeaderText="Price"/>

    </Columns>

</asp:GridView>

 

Binding the Source and the Destination GridViews

Here I am binding the source ASP.Net GridView with some shopping items and the destination GridView is bound with a dummy row.

 

protected void Page_Load(object sender, EventArgs e)

{

    if (!Page.IsPostBack)

    {

        DataTable dt = new DataTable();

        dt.Columns.AddRange(new DataColumn[2] { new DataColumn("Item"), new DataColumn("Price") });

        dt.Rows.Add("Shirt", 450);

        dt.Rows.Add("Jeans", 3200);

        dt.Rows.Add("Trousers", 1900);

        dt.Rows.Add("Tie", 185);

        dt.Rows.Add("Cap", 100);

        dt.Rows.Add("Hat", 120);

        dt.Rows.Add("Scarf", 290);

        dt.Rows.Add("Belt", 150);

        gvSource.UseAccessibleHeader = true;

        gvSource.DataSource = dt;

        gvSource.DataBind();

 

        dt.Rows.Clear();

        dt.Rows.Add();

        gvDest.DataSource = dt;

        gvDest.DataBind();

    }

}

 

Implementing Drag and Drop Functionality using jQuery

I am using the jQuery UI Sortable Plugin to implement the Drag and Drop functionality between the source and the destination GridViews.

 

<script src="http://ajax.aspnetcdn.com/ajax/jquery/jquery-1.8.0.js" type="text/javascript"></script>

<script src="http://ajax.aspnetcdn.com/ajax/jquery.ui/1.8.22/jquery-ui.js"></script>

<link rel="Stylesheet" href="http://ajax.aspnetcdn.com/ajax/jquery.ui/1.8.10/themes/redmond/jquery-ui.css" />

<script type="text/javascript">

    $(function () {

        $(".drag_drop_grid").sortable({

            items: 'tr:not(tr:first-child)',

            cursor: 'crosshair',

            connectWith: '.drag_drop_grid',

            axis: 'y',

            dropOnEmpty: true,

            receive: function (e, ui) {

                $(this).find("tbody").append(ui.item);

            }

        });

        $("[id*=gvDest] tr:not(tr:first-child)").remove();

    });

</script>

 

 

Below are the CSS styles for the source and the destination GridViews

<style type="text/css">

    .GridSrc td

    {

        background-color: #A1DCF2;

        color: black;

        font-size: 10pt;

        font-family:Arial;

        line-height: 200%;

        cursor: pointer;

        width:100px

    }

    .GridSrc th

    {

        background-color: #3AC0F2;

        color: White;

        font-family:Arial;

        font-size: 10pt;

        line-height: 200%;

        width:100px;

    }

    .GridDest td

    {

        background-color: #eee !important;

        color: black;

        font-family:Arial;

        font-size: 10pt;

        line-height: 200%;

        cursor: pointer;

        width:100px

    }

    .GridDest th

    {

        background-color: #6C6C6C !important;

        color: White;

        font-family:Arial;

        font-size: 10pt;

        line-height: 200%;

        width:100px

    }

</style>

 

 

 

Stop auto-fill in browsers for textbox

Today’s browsers like Chrome, Firefox, Internet Explorer and Safari has functionality of auto complete values in TextBoxes. If you have enabled this features in your browser, then each and every time when you start to enter value in TextBox you get a drop down of prefilled values in that TextBox. This feature of browser can be disabled by the programming for a specific web form like payment form and other confidential information form of a web application.

In chrome browser, we can enable auto-fill as shown below:

Suppose we have a below form for online payment of product by credit card or debit card then it is mandatory to stop auto complete functionality of browser so that browser doesn’t save the confidential information of a customer’s credit card or debit card.

We can turn off auto-fill for our complete form by setting autocomplete attribute value to off as shown below:

<form id="Form1" method="post" runat="server" autocomplete="off">

</form>

We can also turn off auto-fill for a particular TextBox by setting autocomplete attribute value to off as shown below:

<asp:TextBox Runat="server" ID="txtConfidential" autocomplete="off">

</form>

We can also do this from code behind also like as:

txtConfidential.Attributes.Add("autocomplete", "off");

Maintain Scroll Position on Postback in ASP.NET 2.0

This article shows how to allows pages to automatically maintain the current scroll position across postbacks.

The MaintainScrollPositionOnPostback page directive attribute allows to do that.

This feature is useful for large pages where scrolling is necessary to view input controls down further on the page.

There are three ways of applying the property to a web page.

1. You can set it programmatically 
   Page.MaintainScrollPositionOnPostBack = true;
2. In the page declaration 
   <%@ Page MaintainScrollPositionOnPostback="true" %>
3. Or in the web.configs <system.web> section. 
   <pages maintainScrollPositionOnPostBack="true" />

This feature is an absolute must-have on large web pages built for postback scenarios.

A simple but very useful feature.

Smartnavigation = true  implemented the same feature in 1.1 framework 

SmartNavigation only had "issues" and it only worked in IE but the new MaintainScrollPositionOnPostback apparently works in most common browsers. 

Sealed classes and Sealed methods in C#.NET

Sealed Classes

When you want to restrict your classes from being inherited by others you can create the class as sealed class.

To create a class as sealed class, create the class using the keyword sealed.

[Access Modifier] sealed class classname
{
}

Sealed Methods 
The virtual nature of a method persists for any number of levels of inheritance.

For example there is a class “A” that contains a virtual method “M1”. Another class “B” is inherited from “A” and another class “C” is inherited from “B”. In this situation class “C” can override the method “M1” regardless of whether class “B” overrides the method “M1”.

At any level of inheritance, if you want to restrict next level of derived classes from overriding a virtual method, then create the method using the keyword sealed along with the keywordoverride.

[Access Modifier] sealed override returntype methodname([Params])
{
}

Different Types of Inheritance

Creating a new class from existing class is called as inheritance.

What is Inheritance in C#

Inheritance can be classified to 5 types.

1. Single Inheritance
2. Hierarchical Inheritance
3. Multi Level Inheritance
4. Hybrid Inheritance
5. Multiple Inheritance

1. Single Inheritance

when a single derived class is created from a single base class then the inheritance is called as single inheritance.




Single Inheritance Example Program

2. Hierarchical Inheritance
when more than one derived class are created from a single base class, then that inheritance is called as hierarchical inheritance.




3. Multi Level Inheritance
when a derived class is created from another derived class, then that inheritance is called as multi level inheritance.




4. Hybrid Inheritance
Any combination of single, hierarchical and multi level inheritances is called as hybrid inheritance.





5. Multiple Inheritance
when a derived class is created from more than one base class then that inheritance is called as multiple inheritance. But multiple inheritance is not supported by .net using classes and can be done using interfaces.



  Multiple Inheritance Example

Handling the complexity that causes due to multiple inheritance is very complex. Hence it was not supported in dotnet with class and it can be done with interfaces.

Senior Level Interview Question and Answer .Net C Sharp

Reflection provides objects (of type Type) that encapsulate assemblies, modules and types. You can use reflection to dynamically create an instance of a type, bind the type to an existing object, or get the type from an existing object and invoke its methods or access its fields and properties. If you are using attributes in your code, Reflection enables you to access them. For more information, see Attributes.

Here's a simple example of Reflection using the static method GetType - inherited by all types from the Object base class - to obtain the type of a variable:

// Using GetType to obtain type information:
int i = 42;
System.Type type = i.GetType();
System.Console.WriteLine(type);

The output is:

System.Int32

In this example, Reflection is used to obtain the full name of a loaded assembly:











// Using Reflection to get information from an Assembly:
System.Reflection.Assembly o = System.Reflection.Assembly.Load("mscorlib.dll");
System.Console.WriteLine(o.GetName());

The output is:

mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089










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Method Overloading in C#.NET
The process of creating more than one method in a class with same name or creating a method in derived class with same name as a method in base class is called as method overloading.
In VB.net when you are overloading a method of the base class in derived class, then you must use the keyword “Overloads”. 
But in C# no need to use any keyword while overloading a method either in same class or in derived class.  While overloading methods, a rule to follow is the overloaded methods must differ either in number of arguments they take or the data type of at least one argument.
Example for Method Overloading
using System; namespace ProgramCall{     class Class1    {         public int Sum(int A, int B)        {            return A + B;        }         public float Sum(int A, float B)        {            return A + B;        }    }     class Class2 : Class1    {        public int Sum(int A, int B, int C)        {            return A + B + C;         }    }     class MainClass    {        static void Main()        {             Class2 obj = new Class2();             Console.WriteLine(obj.Sum(10, 20));             Console.WriteLine(obj.Sum(10, 15.70f));             Console.WriteLine(obj.Sum(10, 20, 30));             Console.Read();        }     }}
Output
3025.760
Note Method overloading provides more than one form for a method. Hence it is an example for polymorphism. 
In case of method overloading, compiler identifies which overloaded method to execute based on number of arguments and their data types during compilation it self. Hence method overloading is an example for compile time polymorphism.
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Method Overriding in C#.NET
Creating a method in derived class with same signature as a method in base class is called as method overriding.
Same signature means methods must have same name, same number of arguments and same type of arguments.  Method overriding is possible only in derived classes, but not within the same class.   When derived class needs a method with same signature as in base class, but wants to execute different code than provided by base class then method overriding will be used.
To allow the derived class to override a method of the base class, C# provides two options,virtual methods and abstract methods.
Examples for Method Overriding in C#
using System;  namespace methodoverriding {     class BaseClass    {         public virtual  string YourCity()         {             return "New York";         }     }      class DerivedClass : BaseClass    {         public override string YourCity()         {             return "London";         }     }      class Program    {                  static void Main(string[] args)         {             DerivedClass obj = new DerivedClass();             string city = obj.YourCity();             Console.WriteLine(city);             Console.Read();         }     } } 
Output London  Example - 2 implementing abstract method
using System;  namespace methodoverridingexample {     abstract class BaseClass    {         public abstract  string YourCity();              }      class DerivedClass : BaseClass    {         public override string YourCity()   //It is mandatory to implement absract method        {             return "London";         }          private int sum(int a, int b)         {             return a + b;         }     }      class Program    {                  static void Main(string[] args)         {             DerivedClass obj = new DerivedClass();             string city = obj.YourCity();             Console.WriteLine(city);             Console.Read();         }     } }
Output London 
*****************************************************************Inheritance in C#
Creating a new class from existing class is called as inheritance.   
    //All the car properties can be used by the supercar
    class SuperCar : car
    {
  
    }
When a new class needs same members as an existing class, then instead of creating those members again in new class, the new class can be created from existing class, which is called as inheritance.  Main advantage of inheritance is reusability of the code.  During inheritance, the class that is inherited is called as base class and the class that does the inheritance is called as derived class and every non private member in base class will become the member of derived class.  If you want the base class members to be accessed by derived class only , you can apply access modifier Protected to the base class member.  There are 5 Different types of inheritance.   Syntax
[Access Modifier] class ClassName : baseclassname
{ 
}
C# Inheritance Example
//Example program demonstrates singular inheritance
using System;
  namespace ProgramCall
{
    class BaseClass
    {
            //Method to find sum of give  2 numbers
        public int FindSum(int x, int y)
        {
            return (x + y);
        }
            //method to print given 2 numbers
        //When declared protected , can be accessed only from inside the derived class
        //cannot access  with the instance of  derived class
        protected void Print(int x, int y)
        {
            Console.WriteLine("First Number: " + x);
            Console.WriteLine("Second Number: " + y);
          }
    }
        class Derivedclass : BaseClass
    {
          public void Print3numbers(int x, int y, int z)
        {
            Print(x, y); //We can directly call baseclass members
            Console.WriteLine("Third Number: " + z);
        }
      }
  
    class MainClass
    {
          static void Main(string[] args)
        {
            //Create instance for derived class, so that base class members              // can also  be accessed
            //This is possible because  derivedclass is inheriting base class
              Derivedclass instance = new Derivedclass();
              instance.Print3numbers(30, 40, 50); //Derived class internally calls base class method.
            int sum = instance.FindSum(30, 40); //calling base class method with derived class instance
            Console.WriteLine("Sum : " + sum);
                Console.Read();
        } 
    }
}
Output First Number: 30 Second Number: 40  Third Number: 50  Sum : 70
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What are Value Types and Reference Types in .Net
           According to MSDN,   A data type is a value type if it holds the data within its own memory allocation. A reference type contains a pointer to another memory location that holds the data.   All the data types in .net are classified in to value types and reference types.  
The data types whose values are directly stored in stack memory area are called as value types and the data types whose values are stored in heap memory area and its address is stored in a variable in stack memory area are called as reference types.
Among all built in data types of .net string and object are reference type and all other data types are value types.
Among user defined data types, class, interface, delegate and arrays are reference type while structure and enumeration are value type.
Value Types---------------- Value types include the following:
All numeric data types
Boolean, Char, and Date
All structures, even if their members are reference types
Enumerations, since their underlying type is always SByte, Short, Integer, Long, Byte, UShort, UInteger, or ULong
Reference Types ----------------------Reference types include the following:
String
All arrays, even if their elements are value types
Class types
Delegates
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