当AutoGenerateColumns为可空的bool时，WPF DataGrid强制绑定DataGridCheckBoxColumn

Question

We have lots of DataGrid with dynamic data binding, so we always use AutoGenerateColumns=True . For bool columns generates a DataGridCheckBoxColumn but for a nullable bool ( bool? in C#) generates the default DataGridTextColumn . Is there any way to force the DataGrid generate automatically a DataGridCheckBoxColumn for nullable bool? Prefer not implementation-dependant hacks. Also some code-behind is accepted for example in the AutoGeneratingColumn event.

Answer 1

you should register to AutoGeneratingColumn event and change the generated column based on column type, like so:

  private void dataGrid1_AutoGeneratingColumn(object sender, DataGridAutoGeneratingColumnEventArgs e)
    {
        if (e.PropertyType == typeof(bool?))
        {
             DataGridCheckBoxColumn  checkBoxColumn=new DataGridCheckBoxColumn();
            checkBoxColumn.Header = e.Column.Header;
            checkBoxColumn.Binding = new Binding(e.PropertyName);
            checkBoxColumn.IsThreeState = true;

            // Replace the auto-generated column with the checkBoxColumn.
            e.Column = checkBoxColumn;
           }
    }

Answer 2

You'd have to try it out - I'm not near VS - but you should be able use this to easily solve it...

Look at the other post of mine ...
how to stop a specific column to be generated in DataGrid when the AutoGenerateColumns is set to True?

Use that 'method' to bind to your command
(all is MVVM straight - you just need an AutoGenerateColumnEvent attached property.

Then in your command handling, like I did there - replace the column - like already suggested.

1) Use the Attach class provided, add namespace etc.

2) And in your XAML...

<DataGrid 
    local:Attach.AutoGenerateColumnEvent="{Binding AutoGeneratingColumnCommand}" AutoGenerateColumns="True" />  

3) And in your view-model...

RelayCommand _autoGeneratingColumnCommand;
public RelayCommand AutoGeneratingColumnCommand 
{ 
    get 
    { 
        return _autoGeneratingColumnCommand ?? (_autoGeneratingColumnCommand = new RelayCommand(param => 
        { 
            var e = param as DataGridAutoGeneratingColumnEventArgs;
            var type = ((PropertyDescriptor)e.PropertyDescriptor).PropertyType;
            if (type == typeof(bool?))
                e.Column = new DataGridCheckBoxColumn();
        }, 
        param => true)); 
    } 
}

Note: For a more generic solution...

You could use the PropertyDescriptor to get the property type - and make a generic decision based on it - that's pretty much what you need I think, I haven't tried though. So you'd have to try it out.