Johnny Harbieh

One Option to Writing a Base Web User Control

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Today I was looking into writing a base web user control to act as an abstract class for other controls. The reason is I had several forms I needed to build and all share the same set of arguments. I looked at creating an interface, but it didn’t cut it for me.  See this reference for more on choosing abstract classes versus interfaces – http://msdn.microsoft.com/en-us/library/scsyfw1d(VS.71).aspx 

Here’s an example of what I was trying to do.

1. Create my base user control. Notice the use of a Virtual method. This will allow me to override the method in my derived class without needing an abstract access modifier declaration on the class itself. Abstract modifiers are not supported on partial classes.

   1: <%@ Control Language="C#" AutoEventWireup="true" 
   2:     CodeBehind="BaseUserControl.ascx.cs" 
   3:     Inherits="Webeccentric.web.UserControls.BaseUserControl" %>
   1: namespace Webeccentric.web.UserControls
   2: {
   3:     public partial class BaseUserControl : System.Web.UI.UserControl
   4:     {
   5:         int _reviewMonth;
   6:         int _reviewYear;
   7:  
   8:         public int ReviewMonth { get { return _reviewMonth; } set { _reviewMonth = value; } }
   9:         public int ReviewYear { get { return _reviewYear; } set { _reviewYear = value; } }
  10:  
  11:         public virtual void Save(){}
  12:     }
  13: }

2. Create a user control that will inherit from my base user control

   1: <%@ Control Language="C#" AutoEventWireup="true" 
   2:     CodeBehind="Review.ascx.cs" 
   3:     Inherits="Webeccentric.web.UserControls.Review" %>
   4:     <div>
   5:         <asp:Label ID="lblMonth" runat="server" Text="" />
   6:     </div>
   7:     <div>
   8:         <asp:Label ID="lblYear" runat="server" Text="" />
   9:     </div>
  10:     <div>
  11:         <asp:Button id="btnSubmit" runat="server" Text="Click Me" 
  12:             onclick="btnSubmit_Click" />
  13:     </div>
   1: namespace Webeccentric.web.UserControls
   2: {
   3:     public partial class Review : BaseUserControl
   4:     {
   5:         protected override void OnLoad(EventArgs e)
   6:         {
   7:             lblMonth.Text = ReviewMonth.ToString();
   8:             lblYear.Text = ReviewYear.ToString();
   9:         }
  10:  
  11:         public override void Save()
  12:         {
  13:             //  Implement the Save operation here
  14:             //  ...
  15:         }
  16:  
  17:         protected void btnSubmit_Click(object sender, EventArgs e)
  18:         {
  19:             Save();
  20:         }
  21:     }
  22: }

3. Create a Page to test the concept and load the control in it

   1: <form id="form1" runat="server">
   2: <div>
   3:     <asp:Panel ID="pnlUserControl" runat="server"></asp:Panel>
   4: </div>
   5: </form>
   1: public partial class _Default : System.Web.UI.Page
   2:     {
   3:         protected void Page_Load(object sender, EventArgs e)
   4:         {
   5:  
   6:         }
   7:  
   8:         protected override void CreateChildControls()
   9:         {
  10:             base.CreateChildControls();
  11:  
  12:             //  Load custom user control with some initial values
  13:             Review review = (Review)Page.LoadControl(@"/UserControls/Review.ascx");
  14:             review.ReviewMonth = 10;
  15:             review.ReviewYear = 2010;
  16:  
  17:             pnlUserControl.Controls.Add(review);
  18:         }
  19:     }

4. That’s it. This should work now.

Hope this helps.

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