ViewModelBase.IsInDesignModeStatic Property - mvvm-light

Question

I am sure this is a MVVM Light newbie error but I need to ask. I am creating an WPF4 application using the MVVM Light framework and Ninject for DI. In the ViewModelLocator contructor I pass in the ViewModelBase.IsInDesignModeStatic value so I know to create DI with DesignTime data or RunTime data.
I thought that when you opened the MainWindow.xml in the designer ( VS2010 or Blend ) that the property would be True and the constructor would execute and break in debug if I had a breakpoint set. The application runs fine and debugs when ran correctly but I never get designtime data because the property is always false. Also does not seem that the constructor is executing when opened in designer. I have watched Laurent's videos multiple times and I know this does work. Can someone please tell me what they think I must be doing wrong.
Orgbrat

Answer 1

I'm late, but try this when troubleshooting this kind of problem.
You'll need a simple Property to test: Create a "Foo" property (string) in the ViewModel and bind it to the XAML (use a TextBlock for example).
In the ViewModel
In the "Get", return an hard coded string (ex: "Step 1". This will validate the "bindings" are valid.
Remove the "Get" hard code, and in the constructor, put a this.Foo = "Step 2" in the first line, this will validate that the constructor is called
Put a third set where the call is "callbacked", this will check that the GetData is being returned
in the "else" of the if (error != null), put the fourth set, and so on...
Example: Here's my MainViewModel constructor.
public MainViewModel(IDataService dataService)
{
this.Foo = "Step 2";
_dataService = dataService;
_dataService.GetData(
(item, error) =>
{
this.Foo = "Step 3";
if (error != null)
{
// Report error here
return;
}
else
{
this.Foo = "Step 4";
}
});
}
My last bug was that I had put the assignment of the data coming back from the GetData in the "if (error != null){...}" ! So it was never called.
Since then, I rewrite the constructor like this:
public MainViewModel(IDataService dataService)
{
_dataService = dataService;
_dataService.GetData(
(item, error) =>
{
if (error == null)
{
// Normal code here
return;
}
else
{
// Report error here
return;
}
});
}