Question

This would seem to be very simple, but it’s not working for me. I desparately need to know how to override the “Text” property of a server control I created, which inherits from “Label”. When the control is dropped into an ASP Web form, I want the text property to already be set to a certain value. I tried:

[Browsable(true), Bindable(true), Category("Behavior"), Localizable(true)]
[DefaultValue("00:00:00")]
public override string Text{get; set;}

But it doesnt work; the “Text” property shows up blank – and when I try to edit it, I can change it to anything except the value specified in the “DefaultValue” attrib. This property is supposed to be overridable.

I also need to be able to set the “ID” property so it’s set to a specific value when dropped on the form. Is this possible?

Any suggestions would be greatly appreciated!

Answer 1

For this you can use the ToolBoxDataAttribute:

Specifies the default tag generated for a custom control when it is
dragged from a toolbox in a tool such as Microsoft Visual Studio.

By default, the visual designer of a tool such as Visual Studio,
creates an empty tag. This is a tag representing a control in its
default state, when the control is dropped from the toolbox of a
visual designer onto the design surface. To specify initial default
values, a control can make use of this attribute. You can use this
attribute to customize the initial HTML content that is placed in the
designer when the control is dragged from the toolbox onto the form.

It would look something like this for your control:

[ToolBoxData("<{0}:TimeLabel ID='TL1' Text='00:00:00' runat='server' />")]
public class TimeLabel : System.Web.UI.WebControls.Label
{
  [DefaultValue("00:00:00")]
  public override string Text
  {
    get { return ViewState["Text"] != null ? (string)ViewState["Text"] : "00:00:00"; }
    set { ViewState["Text"] = value; }
  }
}