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User controls
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  • 1.  A User Control is a file you create that contains a set of other ASP.NET controls and code grouped together to provide common functionality. The user control can then be used on different pages within a Web site. User controls in ASP.NET are created as .ascx files. An .ascx file is similar to the Web page’s .aspx file and can have its own code-behind page. The user controls you create inherit from the UserControl class.
  • 2.  User controls are created using a procedure similar to building a standard Web page. Add New Item -> Web User Control. This adds a file with the .ascx extension to your application. The user control has both a Design and Source view similar to that of an .aspx page. However, a quick glance at the markup reveals the @ Control directive instead of the @ Page directive.
  • 3.  User controls can have their own encapsulated events. This includes life cycle events such as Init and Load. User controls can also cause PostBack for the Web page to which they belong. The event handlers for a user control, however, are typically encapsulated in the given user control. This ensures the code for these events can be maintained independent of the pages that use the user controls.
  • 4. public class AddressEventArgs : EventArgs{public AddressEventArgs(string addressLine1, string addressLine2,string city, string state, string zip){this.AddressLine1 = addressLine1;this.AddressLine2 = addressLine2;this.City = city;this.State = state;this.Zip = zip;}public string AddressLine1 { get; private set; }public string AddressLine2 { get; private set; }public string City { get; private set; }public string State { get; private set; }public string Zip { get; private set; }}
  • 5.  Next, you should declare a delegate. The delegate can be put in the same class file that contains both the event arguments and the user control class. public delegate void SaveButtonClickHandler(object sender, AddressEventArgs e); The next step is to add code to the user control that defines an event and raises that event when the user clicks the button.
  • 6. public event SaveButtonClickHandler SaveButtonClick;protected void ButtonSave_Click(object sender, EventArgs e){if (SaveButtonClick != null){SaveButtonClick(this, new AddressEventArgs(TextBoxAddress1.Text,TextBoxAddress2.Text, TextBoxCity.Text, TextBoxState.Text,TextBoxZip.Text));}}
  • 7.  Finally, you add code to the page that contains the user control. This code should trap the event exposed by the user control. In C#, you wire up a handler using the += syntax inside the Page_Init method. Inside your handler, you use AddressEventArgs as required. protected void Page_Init(object sender, EventArgs e) AddressUc1.SaveButtonClick += this.AddressUc_SaveButtonClick; } private void AddressUc_SaveButtonClick( object sender, AddressEventArgs e) { UserProfile.AddNewAddress(this._userId, AddressUc1.AddressType, e.AddressLine1, e.AddressLine2, e.City, e.State, e.Zip); }
  • 8.  Properties added to user controls can then be configured in the page markup that uses the control. When developers use the user control, they can set the properties declaratively through markup. In fact, these properties are also available through IntelliSense. public int UserId { get; set; } public UserProfile.AddressType AddressType { get; set; }
  • 9.  Imagine the Address user control needs to allow users to preset values of the controls contained by the user control. In this case, you can expose the TextBox.Text properties as properties of the user control. public string AddressLine1 { get { return TextBoxAddress1.Text; } set { TextBoxAddress1.Text = value; } }
  • 10. <%@ Page Language=”VB” AutoEventWireup=”false”CodeFile=”UserProfilePage.aspx.vb” Inherits=”UserProfilePage” %><%@ Register src=”AddressUc.ascx” tagname=”AddressUc”tagprefix=”uc1” %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0Transitional//EN”“http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”><html xmlns=”http://www.w3.org/1999/xhtml”><head runat=”server”><title>User Profile Settings</title></head><body style=”font-family: Verdana; font-size: small”><form id=”form1” runat=”server”><div><uc1:AddressUc ID=”AddressUc1” runat=”server”AddressType=”Home” /></div></form></body></html>
  • 11.  To dynamically load a user control, you use the LoadControl method of the Page class. This method takes the name and path to a file that contains the user control’s definition. The method also returns a reference to the control class it creates. AddressUc addressControl = (AddressUc)LoadControl(“AddressUc.ascx”); form1.Controls.Add(addressControl);
  • 12.  A templated custom Web control provides separation of control data from its presentation. This means that a templated control does not provide a default UI. Instead, this layout is provided by the developer who uses the user control on his or her page. This provides increased flexibility in terms of layout while keeping the encapsulation and reuse benefits of a user control.