Implement LINQ to Entities unsupported method
LINQ to Entities has many LINQ methods marked as "Unsupported" (http://msdn.microsoft.com/en-us/library开发者_如何学C/bb738550.aspx).
Is any way to implement some of these methods by hands? Or I should wait next release of EF?
I'm especially needing this method:
IQueryable<TResult> Select<TSource, TResult>(this IQueryable<TSource> source, Expression<Func<TSource, int, TResult>> selector)
Thanks
UPD: For example I want to use select in this way:
var usersWithRowNumbers = allUsers.Select((u, index) => new {UserID = u.UserID, Index = index});
LINQ to Entities (and other LINQ implementations based in IQueryable<T>
) work by translating expression trees into the target system (in LINQ to Entities: SQL).
To support additional operators, changes would have to be made in that translation layer, which is at the very core of the providers implementation.
Given SQL is set orientated, I doubt any of the query operators which support a delegate or expression tree taking an index will ever be supported.
Something like that?
allUsers.Select(u => new {UserID = u.UserID}).ToList().Select((u, index) => new {UserID = u.UserID, Index = index})
EDIT
If you want to make additional filtering, make it before executing ToList():
allUsers.Select(u => new {UserID = u.UserID}).AdditionalFilters().ToList().Select((u, index) => new {UserID = u.UserID, Index = index})
If it is not solution then please, be more precise with what you want to achieve. Example with data or sql query would be good.
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