WPF DataGrid Not Sorting

Question

I am trying to get a WPF DataGrid to sort by a column by default and it isn't working. there is no sorting happening. The sort icons appear and if i click them then sorting happens.

Right now my table has just the one column. but is it still not sorting it by default.

Any ideas what i am missing?

    <DataGrid.Columns>
            <!--Ordinal-->
            <DataGridTemplateColumn d:DataContext="{d:DesignInstance tabViewModels:ColumnViewModel}"
                                                            SortMemberPath="Ordinal"
                           >
                <DataGridTemplateColumn.HeaderTemplate>
                    <DataTemplate>
                        <Label Content="#" ToolTip="Column Position" />
                    </DataTemplate>
                </DataGridTemplateColumn.HeaderTemplate>
                <DataGridTemplateColumn.CellEditingTemplate>
                    <DataTemplate>
                        <xctk:DoubleUpDown Value="{Binding Ordinal, UpdateSourceTrigger=PropertyChanged, TargetNullValue=''}" />
                    </DataTemplate>
                </DataGridTemplateColumn.CellEditingTemplate>
                <DataGridTemplateColumn.CellTemplate>
                    <DataTemplate>
                        <TextBlock Text="{Binding Ordinal}" />
                    </DataTemplate>
                </DataGridTemplateColumn.CellTemplate>
            </DataGridTemplateColumn>
    </DataGrid.Columns>
    </DataGrid>

Answer 1

One solution would be to use a LINQ query to give the data already sorted to the DataGrid. Modify the getter of the Item Source with something like this:

List<Something> MyItemSource
{
    get
    {
        return _myItemSource.OrderBy(x => x.Ordinal).ToList();
    }
}

then it will for sure sort by Ordinal.