Linq-to-SQL: Ignore null parameters from WHERE clause

Posted by Peter Bridger on Stack Overflow See other posts from Stack Overflow or by Peter Bridger
Published on 2010-03-26T13:50:40Z Indexed on 2010/03/26 13:53 UTC
Read the original article Hit count: 849

Filed under:

LINQ

|

linq-to-sql

|

c#

|

lambda

|

sql

The query below should return records that either have a matching Id supplied in ownerGroupIds or that match ownerUserId. However is ownerUserId is null, I want this part of the query to be ignored.

    public static int NumberUnderReview(int? ownerUserId, List<int> ownerGroupIds)
    {
        return ( from c in db.Contacts
                 where 
                 c.Active == true 
                 &&
                 c.LastReviewedOn <= DateTime.Now.AddDays(-365) 
                 &&
                 ( // Owned by user
                    !ownerUserId.HasValue || 
                    c.OwnerUserId.Value == ownerUserId.Value
                 )
                 &&
                 ( // Owned by group
                    ownerGroupIds.Count == 0 ||
                    ownerGroupIds.Contains( c.OwnerGroupId.Value )
                 )
                 select c ).Count();
    }

However when a null is passed in for ownerUserId then I get the following error: Nullable object must have a value.

I get a tingling I may have to use a lambda expression in this instance?

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