如何绑定到DataGrid / DataTable中的具体对象

Question

Edit: The columns are known only at runtime, which I why I construct the data in a DataTable on the fly.

I have some dynamic data which I have to show in a DataGrid. Each cell in the datagrid is going to bind on to a complex data type. I construct the DataTable successfully and bind onto it. The DataGrid correctly autogenerates its columns, but all the data are strings.

In the code behind (for temporary debugging) I am handling the AutoGeneratingColumn event and trying to set the column type dynamically. If have a complex type:

public class BoolData 
{
    public bool Value { get; set; }
    public Guid Id{ get; set; }
}

In the code behind for the View, I do this:

private void DataGrid_OnAutoGeneratingColumn(object sender, DataGridAutoGeneratingColumnEventArgs e)
{
    if (e.PropertyType == typeof(string))
    {
        var col = new DataGridTextColumn {Binding = new Binding(e.PropertyName)};
        e.Column = col;
        e.Column.Header = e.PropertyName;
    }
    else if (e.PropertyType == typeof(BoolData))
    {
        var col = new DataGridCheckBoxColumn {Binding = new Binding(e.PropertyName + "." + "Value")};
        e.Column = col;
        e.Column.Header = e.PropertyName;
    }
}

The problem is that even where I have added MyBool objects into the DataTable, the string "MyNamespace.MBoolData" is what is in the DataGrid, meaning that the first "if" clause is the only one used. It's as if either the DataGrid or the DataTable is calling ToString() on the object before attempting to display it.

So I guess my question is - how to I create a dynamic DataTable containing complex objects, then bind to it.

Answer 1

You just need to define your columns in XAML and use a DataGridTemplateColumn to define what your complex object should look like. There is a full code example on the linked page, but this is the basics... you define a DataTemplate to describe exactly what the complex object should look like in the UI and then you can set that as the value for the DataGridTemplateColumn.CellTemplate property.

Answer 2

You should try this directly in your XAML.

<DataGrid ItemsSource="{Binding YourDataSource}" AutoGenerateColumns="False" >
    <DataGrid.Columns>
        <DataGridTemplateColumn Header="TheHeaderNameOfYourColumn" Width="SizeToCells">
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <CheckBox IsChecked="{Binding Value}"/>
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>
    </DataGrid.Columns>
</DataGrid>

Answer 3

Without knowing the column name, you should create a template in your DataGrid resource

<DataGrid>
    <DataGrid.Resources>
        <DataTemplate DataType="{x:Type my:BoolData}"> <!--where "my" points to the correct namespace-->
            <CheckBox IsChecked="{Binding Value}"/>
        </DataTemplate>
    </DataGrid.Resources>
</DataGrid>

Answer 4

OK, I figured out what the issue was. If I had pasted in the code for the creation of the DataTable someone would likely have spotted it.

When you're creating your DataTable, specifically your DataColumns, you must explicitly set the DataType, else it defaults to string. Not at all obvious, but finally got it working.