R – SilverLight – MVVM binding viewmodel property to datagrid column

datagridmvvmsilverlightviewmodel

In my SilverLight application, I have a property in my ViewModel called 'vmProperty' and a list called 'dgSource'.

I bind my dgSource to the datagrid as ItemsSource at which point each datagrid row's datacontext changes to each item in dgSource. One of the columns, say a checkbox column, needs to bind to vmProperty. But since the ViewModel is no longer the row's datacontext, I cannot get access to this property.

How do I get around this problem? If the question is not clear, please let me know and I will post a sample. Thanks in advance.

Best Answer

~~Assuming your ViewModel is assigned as the LayoutRoot's DataContext this should work:-~~

~~IsChecked="{Binding DataContext.vmProperty, ElementName=LayoutRoot}"~~

Of course this doesn't work, ultimately a template is replicated and therefore "LayoutRoot" does not exist in the namescope where the binding is actually used.

The simplest solution since this is a ViewModel is to change the model. Expose the required value on the objects available in the dgSource or expose a Parent property that navigates back to the ViewModel.

Related Solutions

C# – silverlight datagrid – binding each row’s style

Change your binding to TemplateBinding. eg

<dg:DataGrid.RowStyle>
            <Style TargetType="dg:DataGridRow">
                <Setter Property="Background" Value="{TemplateBinding Background, Mode=OneTime}" />
            </Style>
</dg:DataGrid.RowStyle>

C# – How to bind column header to property in ViewModel? (WPF MVVM)

Unfortunately, the column definitions of the DataGrid don't inherit the DataContext, because they're not part of the visual tree, so you can't bind directly to the ViewModel. You need to resort to a workaround such as the one described in this article:

<DataGrid.Resources>
    <local:BindingProxy x:Key="proxy" Data="{Binding}" />
</DataGrid.Resources>

...

<DataGridTextColumn Header="{Binding Data.MyTitle, Source={StaticResource proxy}}"/>

Best Answer

Related Solutions

C# – silverlight datagrid – binding each row’s style

C# – How to bind column header to property in ViewModel? (WPF MVVM)

Related Topic