wpf一行的Datagrid ObservableCollection

Question

I want to populate a datagrid with itemsource={Binding Model}. This is not working out. It seems as the datagrid does not understand how to display these properties.

An easy but silly workaround works great:

In viewmodel:

Props= new ObservableCollection<MonitoringBinaryModel>();
_Model = new MonitoringBinaryModel(name);
Props.Add(_Model);

Then in xaml

itemsource={Binding Props}

Seems silly to create an observablecollection when its only suppose to hold one item. Is there a better way to make any type of instance observable?

Answer 1

DataGrid is designed to display a collection of objects of same type. Collection is a must. If you want DataGrid to show a content of your model, you need to obey former's design, by either using ObservableCollection or implementing a bunch of interfaces which would allow your viewmodel's properties to be retrieved in 'collection way'.

I used to have a bunch of models implementing ITypedList interface back in Windows Forms time - it wasn't a simple exercise to say the truth, so if I were you I'd rather go for either way:

• Wrap model into any collection - exactly as you've stated

• Replace data grid with container grid plus a number of direct bindings, like this:

   <Grid> <TextBlock Grid.Column="2" Grid.Row="0" Text="Prop1"/> ... <TextBlock Grid.Column="2" Grid.Row="1" Text="{Binding Prop1}"/> 

Answer 2

Well ItemsSource property is of type IEnumarable so until your MonitoringBinaryModel implement IEnumerable binding will not work.

Again because ItemsSource is IEnumerable you should provide IEnumerable as binding source. So there is no need to make yout Props as ObservableCollection . You can use ordinary List<> , or anything implementing IEnumerable with your single MonitoringBinaryModel :

_Model = new MonitoringBinaryModel(name);
Props = new List<MonitoringBinaryModel> { _Model };

Other option is to use CompositeCollection inside your XAML:

<DataGrid.ItemsSource>
    <CompositeCollection>
        <Binding Path="_Model"/>
    </CompositeCollection>
</DataGrid.ItemsSource>

Answer 3

reusable wrapper via converter:

public class ItemsSourceConverter: IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        // doesn't allow to add new rows in DataGrid
        return Enumerable.Repeat(value, 1);            
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

usage in xaml

add converter to resourses:

<Window.Resources>
    <wpfApplication1:ItemsSourceConverter x:Key="ItemWrapper"/>
</Window.Resources>

and use converter resourse with binding

<DataGrid ItemsSource="{Binding Path=Model, Converter={StaticResource ItemWrapper}}" 
          AutoGenerateColumns="False">
    <DataGrid.Columns>
        <DataGridTextColumn Binding="{Binding Path=Name}"/>
    </DataGrid.Columns>
</DataGrid>

or

<ItemsControl ItemsSource="{Binding Path=Model, Converter={StaticResource ItemWrapper}}">
    <ItemsControl.ItemTemplate>
        <DataTemplate>
            <Label Content="{Binding Path=Name}"/>
        </DataTemplate>
    </ItemsControl.ItemTemplate>
</ItemsControl>