Issues with Properties: DefaultValue & Boolean Types

Question

User1947866343 posted

I'm creating a custom web control to display weather from an xml feed.  I have a couple questions regarding properties. 

1.  I have a boolean property called "ShowForecast".  If I set the default value to True or False, it always returns false when viewed in the browser.  However, if I set the default value to "", it works every time...?  I'm curious if anyone can give me some tips about DefaultValues of properties.

 Works:

     Private _showForecast AS Boolean
     <Category("Appearance"), DefaultValue("")> _
     Public Property ShowForecast() As Boolean
         Get
             Return _showForecast
         End Get
         Set(ByVal value As Boolean)
             _showForecast = value
         End Set
     End Property

  

Doesn't work:

     Private _showForecast AS Boolean
     <Category("Appearance"), DefaultValue(True)> _
     Public Property ShowForecast() As Boolean
         Get
             Return _showForecast
         End Get
         Set(ByVal value As Boolean)
             _showForecast = value
         End Set
     End Property

  

2. I have a string property with a default value of "Images".  I would like "Images" to appear in the property pane the first time the control is dropped onto an aspx/ascx from the toolbox.  No matter what I put in the "DefaultValue" field in my code, they always show up blank.  Any thoughts?

Answer 1

User1340733228 posted

The default value attribute does not actually set the default value for the property as you would think (see http://support.microsoft.com/kb/311339) So if you want the _showForecast to default to true, you need to initialize the _showForecast variable to true. Then, by setting the default value attribute to true, the IDE will not bold it in the properties pane and the extra code will not be generated. If you change the value to false in the IDE, you will see it is in bold and the property will be generated in the code.

Hope that helps.

Answer 2

User1947866343 posted

 That's exactly what I was looking for...thanks!