如何在XAML中指定DataGrid的ItemsSource类型？

Question

I'm binding a DataGrid to an ICollectionView so that I can filter the ItemsSource efficiently, but ICollectionView is not a generic type (as in CollectionView<MyType> ) - it is of type List<object> . So in the XAML editor, VisualStudio can't determine what the type is, so I don't get any IntelliSense help binding to the properties of the object in the collection view. It still builds and runs, but I don't get the help at design time.

Rephrasing the question: Is there anyway to "cast" the data-binding in XAML?

I thought I could do something with <DataGrid.DataContext> , but I can't remember what it was and I haven't had any luck googling for it either:

XAML:

<DataGrid ItemsSource="{Binding MyCollectionView}">
    <DataGrid.DataContext>
        <!-- Specify the type of objects in MyCollectionView somehow -
                 something like 'x:type="MyType"' -->
    </DataGrid.DataContext>
    <DataGrid.RowStyle>
        <Style TargetType="DataGridRow">
            <Style.Triggers>
                <!-- Cannot resolve property 'Approved' in data context of type 'MyProject.MainWindow'. -->
                <DataTrigger Binding="{Binding Approved}" Value="False">
                    <Setter Property="Background" Value="LightGray" />
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </DataGrid.RowStyle>
    <DataGrid.Columns>
        <!-- Cannot resolve property 'Approved' in data context of type 'object'. -->
        <DataGridTextColumn Header="Is Approved"
                            Binding="{Binding Approved}"
                            Width="3*" />
    </DataGrid.Columns>
</DataGrid>

Code Behind:

public partial class MainWindow : Window, INotifyPropertyChanged
{
    public ICollectionView MyCollectionView { get; set; }

    public MainWindow(List<MyType> parameter)
    {
        // ...

        MyCollectionView = new CollectionView(parameter);

        // ...
    }
}

public class MyType
{
    public bool Approved { get; set; }

    // ...
}

Answer 1

I thought I could do something with , but I can't remember what it was and I haven't had any luck googling for it either:

I believe the setting the design time data context is that you are looking for. Please refer to the following links for more information about this.

XAML: Intellisense for Bindings And the Data Context: https://blogs.msmvps.com/deborahk/xaml-intellisense-for-bindings-and-the-data-context/ How to see design-time data-binding in XAML editor (it works in runtime)?

What I'm trying to ask is if there is any way to "cast" the data-binding as a collection of MyType in XAML?

No. But you could specify a design-time DataContext as described above.

Answer 2

VisualStudio can't determine what the type is

Since the type is not expressed until runtime and gotten by using reflection by the code, the designer is at a disadvantage and can only extrapolate on what it knows. And all it knows is that it is an object but not the exact type which the developer knows.

I don't get any IntelliSense help ... still builds and runs, but I don't get the help at design time

If that is the issue which is holding you back, I recommend that you temporarily add a list of the property type in question to the VM (or page if not MVVM) and then bind to that new property. Then the design time will see what it needs and you can get property info add bindings/styles with the help of visual studio.

Once all is good, replace the design time binding, as it were, to the ICollection you mentioned.