WPF Datagrid.ItemsSource作为列表 <Anything> 并在Linq上使用

Question

I'm searching more than 10 hours.

There are 10 classes and 1 datagrid in other window

datagrid1.ItemsSource = new List<class1>(); //+100 items in list
or
datagrid1.ItemsSource = new List<class2>(); //+100 items in list
or
datagrid1.ItemsSource = new List<class3>(); //+100 items in list

I need to convert and use the return items in Linq:

var items = datagrid1.ItemsSource as List<???>;
datagrid1.ItemsSource = items.Where(a => a.GetType().GetProperty("Name").GetValue(a, null).ToString().Contains("text"));

I'm using these. but not work

using System.Linq;

var items = datagrid1.ItemsSource as IList;
//Error CS1061  'IList' does not contain a definition for 'Where' and no extension method 'Where' accepting a first argument of type 'IList' could be found (are you missing a using directive or an assembly reference?)

var items = datagrid1.ItemsSource as List<dynamic>; // return null
var items = datagrid1.ItemsSource as List<object>; // return null

what things I should use instead ??? for support Linq?

Note: I wont use class1 or class2 or class3

Answer 1

Linq extensions are available for generic enumerables ( IEnumerable<> ), IList is basically a IEnumerable , so the extensions will no be available for a IList .

Things like datagrid1.ItemsSource as List<object> returns null because a List<DerivedClass> isn't a List<BaseClass> , you can read more in this questions:

• Convert List<DerivedClass> to List<BaseClass>
• Cannot convert from List<DerivedClass> to List<BaseClass>

You can solve your problem calling Cast<> extension (that is available for IEnumerable ), this extension project the enumerable to a new IEnumerable<> casting each element to the specified generic type:

datagrid1.ItemsSource.Cast<object>().Where(...)

However, if you classes have a common class or interface and as IEnumerable<> is co-variant you try something like this:

interface INamedObject
{
    string Name { get; }
}

var items = datagrid1.ItemsSource as IEnumerable<INamedObject>;
datagrid1.ItemsSource = items.Where(a => a.Contains("text"));