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981

answers:

1

I have tried everything and got nowhere so I'm hoping someone can give me the aha moment. I simply cannot get the binding to pull the data in the datagrid successfully.

I have a DataTable that contains multiple columns with of MyDataType}

public class MyData
{
    string nameData {get;set;}
    boolean showData {get;set;}
}

MyDataType has 2 properties (A string, a boolean) I have created a test DataTable

    DataTable GetDummyData()
    {
        DataTable dt = new DataTable("Foo");
        dt.Columns.Add(new DataColumn("AnotherColumn", typeof(MyData)));
        dt.Rows.Add(new MyData("Row1C1", true));
        dt.Rows.Add(new MyData("Row2C1", false));
        dt.AcceptChanges();
        return dt;
    }    

I have a WPF DataGrid which I want to show my DataTable. But all I want to do is to change how each cell is rendered to show [TextBlock][Button] per cell with values bound to the MyData object and this is where I'm having a tonne of trouble.

My XAML looks like this

            <Window.Resources><ResourceDictionary><DataTemplate x:Key="MyDataTemplate" DataType="MyData">
            <StackPanel Orientation="Horizontal" >
                <Button Background="Green" HorizontalAlignment="Right" VerticalAlignment="Center" Margin="5,0,0,0" Content="{Binding Path=nameData}"></Button>
                <TextBlock Background="Green" HorizontalAlignment="Center" VerticalAlignment="Center" Margin="5,0,0,0" Text="{Binding Path=nameData}"></TextBlock>
            </StackPanel>
        </DataTemplate></ResourceDictionary></Window.Resources>
        <Grid>
  <dg:DataGrid Grid.Row="1" AutoGenerateColumns="True" x:Name="dataGrid1" SelectionMode="Single" CanUserAddRows="False" CanUserSortColumns="true" CanUserDeleteRows="False" AlternatingRowBackground="AliceBlue"  AutoGeneratingColumn="dataGrid1_AutoGeneratingColumn" ItemsSource="{Binding}" />

now all I do once loaded is to attempt to bind the DataTable to the WPF DataGrid

dt = GetDummyData();
dataGrid1.ItemsSource = dt.DefaultView;

The TextBlock and Button show up, but they don't bind, which leaves them blank. Could anyone let me know if they have any idea how to fix this. This should be simple, thats what Microsoft leads us to believe. I have set the Column.CellTemplate during the AutoGenerating event and still get no binding. Please help!!!

+1  A: 

Edit: Updated to reflect the input of Aran Mulholland (see comment)

Apparently the DataGrid is passing the entire DataRowView to each cell. That's why the binding doesn't work. Your DataTemplate expects the DataContext to be of type MyData, but instead it is of type DataRowView. My proposed (somewhat hack-ish) workaround to get the DataContext you want is to create a custom DataGridTemplateColumn that will extract the necessary item from the DataRowView. The code is below:

<Window x:Class="DataGridTemplateColumnSample.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:dg="clr-namespace:Microsoft.Windows.Controls;assembly=WPFToolkit"
    Title="Window1" Height="300" Width="300">
    <Window.Resources>
        <ResourceDictionary>
            <DataTemplate x:Key="MyDataTemplate" DataType="DataRowView">
                <StackPanel Orientation="Horizontal">
                    <Button Background="Green" HorizontalAlignment="Right" VerticalAlignment="Center" Margin="5,0,0,0" Content="{Binding Path=nameData}"></Button>
                    <TextBlock Background="Green" HorizontalAlignment="Center" VerticalAlignment="Center" Margin="5,0,0,0" Text="{Binding Path=nameData}"></TextBlock>
                </StackPanel>
            </DataTemplate>
        </ResourceDictionary>
    </Window.Resources>
    <Grid>
        <dg:DataGrid Grid.Row="1" AutoGenerateColumns="True" x:Name="dataGrid1" SelectionMode="Single" 
                     CanUserAddRows="False" CanUserSortColumns="true" CanUserDeleteRows="False" 
                     AlternatingRowBackground="AliceBlue"  AutoGeneratingColumn="dataGrid1_AutoGeneratingColumn"
                     ItemsSource="{Binding}" />
    </Grid>
</Window>

using System.Data;
using System.Windows;
using Microsoft.Windows.Controls;

namespace DataGridTemplateColumnSample
{
    public partial class Window1
    {
        public Window1()
        {
            InitializeComponent();
            DataContext = GetDummyData().DefaultView;
        }

        private static DataTable GetDummyData()
        {
            var dt = new DataTable("Foo");
            dt.Columns.Add(new DataColumn("OneColumn", typeof(MyData)));
            dt.Columns.Add(new DataColumn("AnotherColumn", typeof(MyData)));
            dt.Rows.Add(new MyData("Row1C1", true), new MyData("Row1C2", true));
            dt.Rows.Add(new MyData("Row2C1", false), new MyData("Row2C2", true));
            dt.AcceptChanges();
            return dt;
        }

        private void dataGrid1_AutoGeneratingColumn(object sender, DataGridAutoGeneratingColumnEventArgs e)
        {
            var column = new DataRowColumn(e.PropertyName);
            column.Header = e.Column.Header;
            column.CellTemplate = (DataTemplate)Resources["MyDataTemplate"];
            e.Column = column;
        }
    }

    public class DataRowColumn : DataGridTemplateColumn
    {
        public DataRowColumn(string column) { ColumnName = column; }
        public string ColumnName { get; private set; }
        protected override FrameworkElement GenerateElement(DataGridCell cell, object dataItem)
        {
            var row = (DataRowView) dataItem;
            var item = row[ColumnName];
            cell.DataContext = item;
            var element = base.GenerateElement(cell, item);
            return element;
        }
    }

    public class MyData
    {
        public MyData(string name, bool data) { nameData = name; showData = data; }
        public string nameData { get; set; }
        public bool showData { get; set; }
    }
}
Joseph Sturtevant
the datagrid passes the row to each column to generate the cell, this is the standard behaviour, the binding on the column defines the cells content. I think your issue is that you are doing everything on code. do you have dynamic amounts of columns? if not just set up your columns and their bindings in xaml.
Aran Mulholland
I agree. If this were my project I would try to avoid doing things this way. Unfortunately project requirements (e.g. dynamic columns) sometimes don't leave you much room to do things the "clean" way.
Joseph Sturtevant
Oh WOW. AWESOME. It works..Thanks. That answers the question 100%.I had figured out that it was the Row being passed but couldn't figure out how to get to the item in that view to bind to. Thanks alot.Unfortunately I don't see how you would avoid doing things this way without knowing the data in advance. Which kinda defeats the objective of having a flexible datagrid that works with non stock columns. Defining your own DataTemplateColumn for instances where the datatype is non-stock columntype, I would have thought would work right out the box. I can dream on, I guess.
Chris J