使用带有转换器的数据网格收集匿名类型

Question

Is it possible to use a converter to return .ToList() of a collection anonymous types bound to the Itemssource of a Datagrid ?

I have tried this:

//converter

 class AnonymousTypeToListConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return ((ObservableCollection<Object>)value).ToList();
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return value;
        }
    }

//Datagrid Declaration in xaml

<DataGrid ItemsSource="{Binding SelectionData, Converter={StaticResource anonConverter}}" AutoGenerateColumns="True"/>

This doesn't seem to work - the Converter gets called but my Datagrid is blank:

My reason for this is because Datagrid doesn't like anonymous types...as defined here but I don't think this approach really works for us using an MVVM approach...

Answer 1

The comments are so hard to read, so I'll continue in an answer.

What he meant to say was that he could not use an IEnumerable as the DataContext and so he chose the option to call ToList() to turn it into a List . As I showed you in my last comment, he could just as easily have passed the IEnumerable into the ObservableCollection<T> constructor:

DataContext = new ObservableCollection(
    list.Select(v => new { id = v, name = "name " + v })); 

There's no point in you casting your ObservableCollection<Location> into an ObservableCollection<Object> like you are doing in your Converter . I still don't get what it's for anyway, but you'd be better off doing this:

public object Convert(object value, Type targetType, object parameter, 
CultureInfo culture)
{
    return new ObservableCollection<Location>((ObservableCollection<Location>)value);
}

Of course, there's no point in casting an ObservableCollection<Location> into an ObservableCollection<Location> and then passing it into a new ObservableCollection<Location> but I'm guessing that you'll actually be doing something else in there.

If you tell us what you're actually trying to achieve with your Converter , then maybe you'd get some better answers?

Answer 2

Objects with an anonymous type are internal. You can bind to properties of anonymous types only when running in full trust.

In general, Internet applications should be restricted from having direct access to critical system resources, to prevent malicious damage. By default, HTML and client-side scripting languages are not able to access critical system resources. Because Windows Presentation Foundation (WPF) browser-hosted applications can be launched from the browser, they should conform to a similar set of restrictions. To enforce these restrictions, WPF relies on both Code Access Security (CAS) and ClickOnce.

To cut the story short, WPF runs with partial trusted security and therefore Binding doesn't work with anonymous types by default.

However I bet there are "workarounds" on the internet. :)