How to bind List<string> and display its collection into a DataGridTemplateColumn

Question

I'm trying to display a list of string items on a column in my DataGrid. But if I just bind the List object what it displays is the text (Collection). Every other data in my DataGrid comes up fine, except for this column. I would like for it to display the contents of said collection.

In my ViewModel I have:

 /// <summary>
/// The list I'm binding to the Itemsource
/// </summary>
public ObservableCollection<Foo> FooCollection
{
    get
    {
        return _fooCollection;
    }
    set
    {
        if(_fooCollection != value)
        {
            _fooCollection  = value;
            RaisePropertyChanged(nameof(FooCollection));
        }
    }
}
private ObservableCollection<Foo> _fooCollection = new ObservableCollection<Foo>();

public MyViewModel()
{
    FooCollection = _myServices.GetFooCollection();
}

In my XAML I have:

 <DataGrid
            ItemsSource="{Binding FooCollection, Mode=OneWay}"
            VerticalScrollBarVisibility="Auto"
            AutoGenerateColumns="False"
            HorizontalAlignment="Left"
            VerticalAlignment="Stretch"
            BorderThickness="3"
                  Margin="10,10,10,17"
            CanUserAddRows="False"
            CanUserDeleteRows="False"                 
            Grid.Row="2"
            SelectionMode="Single"
            IsReadOnly="True" >
     <DataGrid.Columns>
     <!--Other column definitions-->
     <DataGridTextColumn
                    Header="Places"
                    Binding="{Binding Places}">
                </DataGridTextColumn>
     </DataGrid.Columns>
</DataGrid>

In my DataModel I have:

public class Foo:
{
        /// <summary>
        /// Roles
        /// </summary>
        public List<string> Places { get; set; }

        //... Constructors

        //... Methods
}

Answer 1

You can use a value converter, e.g.:

public class ListToStringConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value!= null && value is List<string> lstStr)
        {
            return string.Join(",", lstStr);
        }
        return value?.GetType().ToString();
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException("One way converter!");
    }
}

XAML:

<DataGrid ...>
    <DataGrid.Resources>
        <local:ListToStringConverter x:Key="lstToString"/>
    </DataGrid.Resources>
     <DataGridTextColumn
                    Header="Places"
                    Binding="{Binding Places, Converter="{StaticResource lstToString}"}">
                </DataGridTextColumn>
     </DataGrid.Columns>
</DataGrid>