I get errors when viewing forms in the designer - how can i avoid this?

Question

Some of my forms show errors when i load them in the designer. This is because in their constructors they use system settings loaded from a configuration file. When the form is loaded in the designer it uses some random path and unsurprisingly the config file isn't there.

eg. The configuration file C:\Documents and Settings\Rory\Local Settings\Application Data\Microsoft\VisualStudio\8.0\ProjectAssemblies\it3dtcgg01\PrioryShared.dll.config could not be found.

Is there some way I can deal with this so that the form displays correctly in the designer? eg:

if (!inDesignerMode) 
{ 
    loadSettingsFromConfigFile();
}

UPDATE: ok, I'm still getting this error. The composition is like this

• MyForm.cs

  • MyCustomControl.cs

In MyCustomControl's constructor I've put

if (!this.DesignMode)
{
    // Get settings from config file   <- this is where the error occurs
}

but it's on that line that I still get the error in the designer. What gives?

UPDATE: Worth noting this link that describes how to debug design-time controls.

UPDATE: Control.DesignMode isn't set to true when called within the constructor (MSDN) of the object! So that sort of code should go in the onLoad. Alternatively you can use an approach like this

Answer 1

Page.DesignMode

This can be used in all pages and user controls.

Answer 2

How about simply putting that logic into OnLoad instead, and check DesignMode?

protected override void OnLoad(System.EventArgs e)
{
    base.OnLoad(e);
    if (!this.DesignMode)
    {
        /* do stuff */
    }        
}

Answer 3

You should wrap the items in a check on this.DesignMode, which is set to true when in the designer, or move them to OnLoad or some other place that doesn't get called during designer use.

Answer 4

Alternatively, you can do something like this:

public bool IsDesignMode
{
   get
      {
         return (System.Diagnostics.Process.GetCurrentProcess().ProcessName == "devenv");
      }
}

Answer 5

This is what I do when I have to do some special handling if the control is currently used by the designer.

public MyControl() {
  InitializeComponent();
  if (LicenseManager.UsageMode != LicenseUsageMode.Designtime)  {
    // Put stuff here that should not be run while in the designer
  }
}

Answer 6

I've always found it to be a mistake for a control to use a configuration file. Instead, the control should have settable properties, and if the form using it wants to set those properties from configuration, then it's welcome to do so.