Linq - How to query specific columns and return a lists

Question

Hello Everyone, I am trying to write a linq query that will only return certain columns from my entity object into a list object.

Below is my code which produces an error(can't implicitly convert a generic list of anonymous types to a generic list of type TBLPROMOTION):

IQueryable<TBLPROMOTION> matches = webStoreContext.TBLPROMOTION.Include("TBLSTORE").Include("LKPROMOTIONTYPE");

List<TBLPROMOTION> promotionInfo = null;

promotionInfo = (from p in matches
                orderby p.PROMOTION_NM descending
                select new { p.EFFECTIVE_DT, p.EXPIRE_DT, p.IS_ACTIVE, 
                p.PROMOTION_DESC, p.PROMOTION_ID, p.PROMOTION_NM }).ToList();

What would be the best way to accomplish this. I do not want to do a "select p" in this case and return all the columns associated with the query.

thanks in advance, Billy

Answer 1

did you try

 select new TBLPROMOTION {.....

instead of

 select new {.....

Answer 2

Can't you do var promotionInfo = () and get a list of anonymous types?

Answer 3

List<TBLPROMOTION> promotionInfo = null;

promotionInfo = (from p in matches
                orderby p.PROMOTION_NM descending
                select new TBLPROMOTION { COL1 = p.EFFECTIVE_DT, COL2 = p.EXPIRE_DT, COL3 = p.IS_ACTIVE... }).ToList();

Where COL1, COL2, ... are the names of the properties on TBLPROMOTION you wish you populate.

Answer 4

If you want a subset of the table you have 2 options:

• @Fredou mentioned select new TBLPROMOTION{...}

• other way is to create a custom DTO which has the exact properties & select them instead like:

  List promotionInfo = ... select new TBLPROMOTION_DTO{ Effective_dt = ... }

HTH

Answer 5

Okay, basically you can not cast an Anonymous type to a known type like TBLPROMOTION.

ofcourse, you can say var promotionInfo = and then get an IEnumerable<{Anonymoustype}> and use that to do, what you were wanting to do with promotionInfo.

Also, personally I prefer the Fluent version of a linq query, easy on the eyes, good programming diet, at least for me :)

var promotionInfo = matches
                .OrderByDescending( p => p.PROMOTION_NM)
                .Select( p => new { p.EFFECTIVE_DT, 
                                p.EXPIRE_DT, 
                                p.IS_ACTIVE, 
                                p.PROMOTION_DESC, 
                                p.PROMOTION_ID, 
                                p.PROMOTION_NM})
                .ToList();