Binding Enum with entity not working - wpf

Question

I have a table Called IGdaily with Field Trans_Category. I want to bind a DataGridComboBoxColumn displaying enum and binds its int value to datagrid cell Trans_Category.
My Enum
public enum Enm_Purch_Ret : short
{
Purchase = 1,
Sale = 2,
Return = 3
}
Viewmodel Vm_Purchase
public class Vm_Purchase : INotifyPropertyChanged
{
private IGoldEntities db = new IGoldEntities();
public ObservableCollection<IGdaily> Vm_IGdaily { get; set; }
public ObservableCollection<Enm_Purch_Ret> Vm_Enum_P_R { get; set; }
public Vm_Purchase()
{
Vm_IGdaily = new ObservableCollection<IGdaily>();
Vm_Enum_P_R = new ObservableCollection<Enm_Purch_Ret>(Enum.GetValues(typeof(Enm_Purch_Ret)).Cast<Enm_Purch_Ret>().ToList());
}
public ObservableCollection<IGdaily> IGDailys
{
get { return Vm_IGdaily; }
set { Vm_IGdaily = value; NotifyPropertyChanged(); }
}
public ObservableCollection<Enm_Purch_Ret> Enm_Purch_Rets
{
get { return Vm_Enum_P_R; }
set { Vm_Enum_P_R = value; NotifyPropertyChanged(); }
}
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged([CallerMemberName] string propertyName = "")
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
In XAML
<Window.DataContext>
<local:Vm_Purchase/>
</Window.DataContext>
<DataGrid x:Name="DG" ItemsSource="{Binding IGDailys}" AutoGenerateColumns="False" SelectionMode="Single" SelectionUnit="Cell" >
<DataGrid.Columns>
<DataGridTextColumn Binding="{Binding GroupName}" Header="Name" Width="200"/>
<DataGridComboBoxColumn Header="Item/Metal" SelectedValueBinding="{Binding Trans_Category}" SelectedValuePath="{Binding Path=Enm_Purch_Rets, StringFormat='\{0:D\}'}" DisplayMemberPath="Enm_Purch_Ret">
<DataGridComboBoxColumn.ElementStyle>
<Style TargetType="{x:Type ComboBox}">
<Setter Property="ItemsSource" Value="{Binding Path=DataContext.Enm_Purch_Rets, RelativeSource={RelativeSource AncestorType={x:Type Window}}}" />
</Style>
</DataGridComboBoxColumn.ElementStyle>
<DataGridComboBoxColumn.EditingElementStyle>
<Style TargetType="{x:Type ComboBox}">
<Setter Property="ItemsSource" Value="{Binding Path=DataContext.Enm_Purch_Rets , RelativeSource={RelativeSource AncestorType={x:Type Window}}}" />
</Style>
</DataGridComboBoxColumn.EditingElementStyle>
</DataGridComboBoxColumn>
<DataGridTextColumn Binding="{Binding Trans_Category}" ClipboardContentBinding="{x:Null}" FontSize="14" Header="Metal Id" Width="100"/>
</DataGrid.Columns>
</DataGrid>
public partial class IGdaily
{
public int GDaily_Id { get; set; }
public int DailyMast_Id { get; set; }
public int ItemGroup_Id { get; set; }
public int Item_Id { get; set; }
public int Trans_Category { get; set; }
}
Please help what is my mistake in binding. I am new to MVVM pattern.
please explain
Thanks

Answer 1

You can't set an int property to a Enm_Purch_Ret value because there is no implicit conversion between these two types.
But you could use a converter class that peforms the conversion for you:
public class EnumConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
Enm_Purch_Ret e = (Enm_Purch_Ret)value;
return (int)e;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
int i = (int)value;
return (Enm_Purch_Ret)i;
}
}
Usage:
<DataGrid x:Name="DG" ItemsSource="{Binding IGDailys}" AutoGenerateColumns="False" SelectionMode="Single" SelectionUnit="Cell" >
<DataGrid.Resources>
<local:EnumConverter x:Key="conv" />
</DataGrid.Resources>
<DataGrid.Columns>
<DataGridTextColumn Binding="{Binding GroupName}" Header="Name" Width="200"/>
<DataGridComboBoxColumn Header="Item/Metal"
SelectedItemBinding="{Binding Trans_Category, Converter={StaticResource conv}}">
<DataGridComboBoxColumn.ElementStyle>
<Style TargetType="{x:Type ComboBox}">
<Setter Property="ItemsSource" Value="{Binding Path=DataContext.Enm_Purch_Rets, RelativeSource={RelativeSource AncestorType={x:Type Window}}}" />
</Style>
</DataGridComboBoxColumn.ElementStyle>
<DataGridComboBoxColumn.EditingElementStyle>
<Style TargetType="{x:Type ComboBox}">
<Setter Property="ItemsSource" Value="{Binding Path=DataContext.Enm_Purch_Rets , RelativeSource={RelativeSource AncestorType={x:Type Window}}}" />
</Style>
</DataGridComboBoxColumn.EditingElementStyle>
</DataGridComboBoxColumn>
<DataGridTextColumn Binding="{Binding Trans_Category}" ClipboardContentBinding="{x:Null}" FontSize="14" Header="Metal Id" Width="100"/>
</DataGrid.Columns>
</DataGrid>