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How to Create Alphabetical Paging Control in Asp.Net



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Add Date: 10/06/2012
This article is going to show you, how to create an alphabetic paging control in Asp.Net applications with three different methods.
Introduction
This article explains the concept of creating Alphabetical Paging Control in Asp.Net. Three different methods of alphabetical paging are explained with free and source code to download.

Description
Most web applications, which are displaying contents in a grid or list style, includes the Paging Technique, otherwise, the Pager, to reduce the length of the list displayed in a page. On technical aspect, it reduces the time taken for a page to load in the Internet. From the user perspective, user got the freedom to look at any page, by just click on the desired page numbers to view its content.

This article is going to show you, how to create an alphabetic paging control in Asp.Net applications with three different methods. Method 1, is creating a pager control with alphabets from A to Z, Method 2 is creating a pager control with the alphabets that is available in the database table, and method 3 is achieving both method 1 and 2 by using a Stored Procedure.

Straight to the Job
Open an aspx page in your Visual Studio, add a DataList and a GridView control into it. The DataList control is the Pager control, used to display the Page Numbers, in our terms Paging Alphabets and the GridView control is used to display the list of customers from the SQL Server database. First, in the Item Template section of the DataList, add a LinkButton and name it as lnkbtnPaging. Bind the Text and CommandArgument property of the LinkButton with the value as PageText and PageIndex respectively. PageText and PageIndex are the two columns from the DataTable, which we are going to create in the code-behind section to bind with this DataList. This DataTable will have values used for paging. Note that both PageText and PageIndex will have the same value. Then design the GridView control to display columns from the Customer table. For the purpose of this article, we are going to display the Customer Name, Age, Gender and Email Id along with their some date. So the aspx page is ready, now we are going to move on the code-behind section. In this article, we are going to show you three different methods of creating a Paging control. Lets go one by one.

Method 1: Create Pager with Alphabets from A-Z
The first method is to create an alphabetical paging control with alphabets from A to Z. For this we have to loop through 65 to 90, and convert the value to its equivalent character, which is from A to Z. Then store each value into a DataTable row and bind it with the DataList control. The code for this method is given below


The above method creates a DataTable with two columns PageIndex and PageText. We loop through 65 to 90, whose ASCII character equivalent is from A to Z. We are using Char.ConvertFromUtf32 method to convert the number to alphabets. After conversion we assign the value to the PageIndex and PageText columns of the DataTable. Sometimes, the user needs to view all the data in a single page. To provide this option we have added another DataRow with value “All”. We have also used a ViewState variable in this method, in order to avoid the for-loop being executed every time this method is called. So for the first time, when the page loads, the ViewState is empty or null, thus execute the for-loop to create the rows for the DataTable, then the DataTable created will be stored in the ViewState called “Paging”. When this method is called subsequently, the ViewState “Paging” it will supply the alphabetical paging DataTable rows. Finally we bind the DataList is bind with the paging DataTable.

Bind the GridView control
To display the Customer information in a GridView control, we create a method called BindGrid, which takes a parameter called StartAlpha. This parameter is responsible to filter the customer records before binding it with the GridView control. If the parameter value is “All”, then all records will be displayed in the GridView control. The BindGrid method is given below.


Page Load Event
In the page load event, we have to display the pager in the DataList and the Customer information in the GridView control.

In the first line, we create a ViewState variable as SelectedText and assign value as “All”. The second line calls the pager method, which will bind the DataList with alphabets from A to Z. The last line calls the BindGrid method with ViewState variable SelectedText as its parameter. So when the page loads the GridView will display all the Customer records.

DataList ItemCommand Event
When the alphabets in the DataList is clicked, it has to filter the records in the GridView control. Now look at the below code.


In the ItemCommand of the DataList control, we try to achieve two tasks. The first task is to enable the paging and second task is to disable the clicked pager link. So in the first line, we find the LinkButton inside the DataList control, in second line we call the BindGrid method, which is responsible to bind the Customer Information with the GridView control based on the parameter passed. Then we reassign the ViewState SelectedText with the new value of the selected pager LinkButton. Last, we call the CreateAlphaPagings method to bind the DataList control.

The intention to call the CreateAlphaPagings method repeatedly is to bind the DataList control to disable the clicked Pager LinkButton. This can be achieved by the writing a small piece of code in the DataList ItemDataBound event.

DataList ItemDataBound Event

In the above block of code, we check the value in the ViewState and the LinkButtons’s Text value inside the DataList control. If both matches, then we make the LinkButton’s Enabled property as false. So this will disable the most recently selected LinkButton.

Save all and press F5. Your browser will open with Alpabetical Paging Control and the GridView will display all the Customer records. Click on the Pager link on any alphabets. The GridView will display only records starts with the alphabet you clicked. That’s it.

Method 2: Create Pager with Alphabets available in SQL Server Table

Instead of creating a pager will all alphabets from A to Z, it is better to create a pager with alphabets that is available in the SQL Server Table, in our case in Customer Table. This helps the user from not clicking on alphabets with no records. To achieve this, we create a method that queries the Customer Table to return only the first character from the Customer Name column. Rest everything is usual.


Method 3: Create Alphabetic Pager with Stored Procedure

We all knew the benefits of using Stored Procedures in the web applications. Not only the performance of the application, but the code reusability has also to be considered to create a Stored Procedure. So we have shown here the easy way to create an Alphabetical Pager using Stored Procedure. Our Paging Stored Procedure is designed in such a way to handle both the methods mentioned above, it will return either alphabets from A to Z or it will return only the alphabets that is available in Customer table. The structure of the Stored Procedure is given below



The Stored Procedure takes a parameter @OptionId to decide the type output. If the parameter @OptionId is 1, it will return all alphabets from A to Z. Otherwise it will return only the first letter of the Customer Name column in the Customer Table.

To create the pager, we have to bind the Stored Procedure with the DataList control with the following code.


So, we have shown you three ways to create an Alphabetical Paging Control. We always recommends the Method 3 as the best option, but it is upto you to decide based on your requirements.

Happy Programming!!!

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