Problem updating LINQ results with anonymous type...read only?

Question

Hello,

I'm learning LINQ and have run into a problem. I created a simple query against the northwind db, and I'm shaping the fields that should be returned. The problem is After run , I can't modify any of the fields in my AspxGridView .

<dxwgv:ASPxGridView ID="ASPxGridView1" runat="server" 
    AutoGenerateColumns="False" KeyFieldName="CategoryID">
    <Columns>
        <dxwgv:GridViewCommandColumn VisibleIndex="0">
            <EditButton Visible="True">
            </EditButton>
            <NewButton Visible="True">
            </NewButton>
            <DeleteButton Visible="True">
            </DeleteButton>
        </dxwgv:GridViewCommandColumn>
        <dxwgv:GridViewDataTextColumn Caption="CategoryID" FieldName="CategoryID" 
            VisibleIndex="1">
        </dxwgv:GridViewDataTextColumn>
        <dxwgv:GridViewDataTextColumn Caption="CategoryName" FieldName="CategoryName" 
            VisibleIndex="2">
        </dxwgv:GridViewDataTextColumn>
        <dxwgv:GridViewDataTextColumn Caption="Description" FieldName="Description" 
            VisibleIndex="3">
        </dxwgv:GridViewDataTextColumn>
    </Columns>
</dxwgv:ASPxGridView>

C# syntax:

protected void Page_Load(object sender, EventArgs e)
{
    NorthwindDataContext db = new NorthwindDataContext();
    var r = db.Categories
        .Select(p=>new {p.CategoryID,p.CategoryName,p.Description});
    ASPxGridView1.DataSource = r;
    ASPxGridView1.DataBind();
}

You guys may say it's problem for var anonymous type .But i always need to use anonymous type.How to solve this problem

Answer 1

Don't think it is possible.

Anonymous types are class types that consist of one or more public read-only properties.

Quoted from http://msdn.microsoft.com

Answer 2

This isn't possible.

Scott Guthrie covered it in part 9 of his LINQ to SQL series:

One feature that will not work with custom shapes/projections, though, is inline editing support. This is because we are doing a custom projection in our Selecting event, and so the LinqDataSource has no way to safely know how to update an underlying entity object. If we want to add editing support to the GridView with a custom shaped type, we'd want to either move to using an ObjectDataSource control (where we could supply a custom Update method method to handle the updates), or have the user navigate to a new page when performing updates - and display a DetailsView or FormView control that was bound to a Product entity for editing (and not try and do inline editing with the grid).