Asp.net slide8

Asp.net slide

Session 15

Custom Controls in

ASP.NET

 Data binding is the process of linking data retrieved from a

database to the control, which will display the data

 Repeater control is a container control, which can be used to

display a list of data This control has no form of its own.

 DataList control can be used for displaying data, and it enables to

specify the flow of data.

 Values to be passed to the database for insertion are attached to

the command object with the help of the Parameters collection.

 Assigning the index of the row to be updated to the EditItemIndex

property makes that row editable.

 The System.IO namespace has to be imported to read XML data.

 XML data can be read only into a DataSet, and not into a

DataReader

controls

 Just as classes are built for code re-usability, it

also becomes necessary to re-use existing user

 ASP.NET controls are mostly used for the web,

generating HTML or WML, which is displayed on the client’s browser

Controls Contd…

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Assfffghfioi Jhjkhjkhjkhj Uyuuiyuiyui ghghghjggg

Assfffghfioi Jhjkhjkhjkhj Uyuuiyuiyui ghghghjggg

Code for a dataview

Code for a radiobutton

Code for a checkbox

Code for a button

Code for a datagrid

Code for a Label

Code for a textbox

Custom Controls

Created in two ways

ASP.NET like Page

Pagelets

C#

Custom Control using Label

Control

MyLabel.ascx

<% @Control Language="C#" Debug="True" %>

<ASP:Label id="lblOne" runat="server" style="color:Red;

font-family: arial; font-size=40pt"></asp:Label>

<script language="C#" runat="server">

public string MyText

Custom Control using Label Control

<MyFirstControl:MyLbl runat="Server" id ="AllMine"

MyText="My first custom control !!!" />

Custom Controls Using C#

This control is completely programmed using C# and without using any existing

Custom Controls Using C#

for (intCount=1; intCount<=3; intCount++)

The code is saved with a cs extension since it is a C# file, which will be compiled

into an assembly This is done by typing the following command at the DOS

prompt

csc /t:library /r:System.dll,System.Web.Dll Repeater.cs

The command creates Repeater.dll, which is placed in the bin directory of the

application

Custom Controls Using C#

The custom control created using C# can be used in an aspx page as follows:

<% @Register TagPrefix="Mine" Namespace="MyOwnControls"

Properties of Custom Controls

 In order to enable a better reuse of the control it is possible to

create properties for the control

 These properties can be modified dynamically, thus allowing the

user to use the control in most flexible manner

 The code Repeater.cs in the previous example can be modified to

specify the text to be printed and the number of times it should be

Properties of Custom Controls

public string myText;

public int TimesToRepeat

else timesToRepeat = value;

}

}

Properties of Custom Controls

public string MyText

else myText = value;

}

}

Properties of Custom Controls

protected override void Render(HtmlTextWriter writer)

Composite Controls

 Simple controls can be clubbed together to form more complex controls

 Complex controls, which comprise one or more

simple controls, are known as Composite

controls

 Composite controls can comprise custom

controls, as well as windows controls

 Every ASP.NET page which includes at least one control, can be referred (the ASP.NET page

itself) to as a composite control

Composite Controls - Example

this.EnsureChildControls();

return Int32.Parse (((TextBox) Controls[1]) Text); }

Composite Controls - Example

set { this.EnsureChildControls();

((TextBox)Controls[1]).Text = value.ToString();

} }

protected override void CreateChildControls()

{

this.Controls.Add(new LiteralControl("<h3>Value: "));TextBox box = new TextBox();

Composite Controls - Example

This composite control created can be used within a aspx page, just like any

other custom control that has been created

<script language="C#" runat="server">

private void AddBtn_Click(Object sender, EventArgs e)

Composite Controls - Example

<asp:button text="Subtract" OnClick="SubtractBtn_

Click" runat="server" ID="btnSubtract" />

</form>

</body>

</HTML>

Composite Controls - Output

 Web Controls using C#

 Pagelets are custom controls that look like an asp page, and have the extension ascx

 Web Controls render HTML automatically.

 Custom Controls, which compose of other controls as well, are known as composite controls.

 The System.Web.UI.INamingContainer interface has

no methods; it is used by ASP.NET to create unique IDs