Is there a way to check if WPF is currently execut

Question

Does anyone know of some global state variable that is available so that I can check if the code is currently executing in design mode (e.g. in Blend or Visual Studio) or not?

It would look something like this:

//pseudo code:
if (Application.Current.ExecutingStatus == ExecutingStatus.DesignMode) 
{
    ...
}

The reason I need this is: when my application is being shown in design mode in Expression Blend, I want the ViewModel to instead use a "Design Customer class" which has mock data in it that the designer can view in design mode.

However, when the application is actually executing, I of course want the ViewModel to use the real Customer class which returns real data.

Currently I solve this by having the designer, before he works on it, go into the ViewModel and change "ApplicationDevelopmentMode.Executing" to "ApplicationDevelopmentMode.Designing":

public CustomersViewModel()
{
    _currentApplicationDevelopmentMode = ApplicationDevelopmentMode.Designing;
}

public ObservableCollection<Customer> GetAll
{
    get
    {
        try
        {
            if (_currentApplicationDevelopmentMode == ApplicationDevelopmentMode.Developing)
            {
                return Customer.GetAll;
            }
            else
            {
                return CustomerDesign.GetAll;
            }
        }
        catch (Exception ex)
        {
            throw new Exception(ex.Message);
        }
    }
}

Answer 1

There are other (maybe newer) ways of specifying design-time data in WPF, as mentioned in this related answer.

Essentially, you can specify design-time data using a design-time instance of your ViewModel:

d:DataContext="{d:DesignInstance Type=v:MySampleData, IsDesignTimeCreatable=True}"

or by specifying sample data in a XAML file:

d:DataContext="{d:DesignData Source=../DesignData/SamplePage.xaml}">

You have to set the SamplePage.xaml file properties to:

BuildAction:               DesignData
Copy to Output Directory:  Do not copy
Custom Tool:               [DELETE ANYTHING HERE SO THE FIELD IS EMPTY]

I place these in my UserControl tag, like this:

<UserControl
    ...
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 

    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    ...
    d:DesignWidth="640" d:DesignHeight="480"
    d:DataContext="...">

At run-time, all of the "d:" design-time tags disappear, so you'll only get your run-time data context, however you choose to set it.

Edit You may also need these lines (I'm not certain, but they seem relevant):

xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
mc:Ignorable="d" 

Answer 2

You can do something like this:

DesignerProperties.GetIsInDesignMode(new DependencyObject());