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If you are working with items from one of the Generic Content based modules, or a custom one based on Generic Content, the best approach would be not to use a LINQ data source. You should bind the RadGrid to a custom object data source, that is of type Telerik.Cms.Engine.ContentManager. If for example we are working with news items we would instantiate this object data source to to a content manager that has a provider set to a news provider. I have prepared a sample how to bind the grid to an object data source of the needed type, and how to display items from the data source. You can build on top of it similar logic for inserting, and updating content items. Bellow is a link on the Content Items API walkthtrough that will help you understand how to work with content items:
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