Question

I’m trying to create an “AssociateWith” data load option for my context to filter rows that the current user has access to. My simple data model is as such:

Tables
UserPermissions
PK: ID
FK: RelatedUserID nullable
FK: RelatedItemID not nullable

Users
PK: ID

Items
PK: ID
FK: RelatedCategoryID not nullable

Categories
PK: ID

On my datacontext, I’m trying to do something like:

//dbContext is my LINQ context 
//current_user_id is the id of my current logged in user 
var dlo = new DataLoadOptions();
//issue->UsersPermissions is one->many relationship
// if I omit this LoadWith line, no associatewith filter
// is created in the generated sql code
dlo.LoadWith<Items>(i=>i.UserPermissions); 

dlo.AssociateWith<Items>(i=>
i.UserPermissions.Where(p=>
p.RelatedUserID.HasValue && p.RelatedUserID.Value == current_users_id));
dbContext.LoadOptions = dlo;

Everything seems reasonable to me, but the query generated in SQL looks like this:

SELECT [t0].[ID], [t1].[ID] AS [ID2], [t1].[RelatedUserID], [t1].[RelatedItemID] 
(SELECT COUNT(*)
FROM [dbo].[UserPermissions] AS [t2]
WHERE (([t2].[RelatedUserID] = @p0)) AND ([t2].[RelatedItemID] = [t0].[ID])
) AS [value]
FROM [dbo].[Items] AS [t0]
LEFT OUTER JOIN [dbo].[UserPermissions] AS [t1] ON ([t1].[RelatedUserID] = @p0) 
AND     
([t1].[RelatedItemID] = [t0].[ID])
ORDER BY [t0].[ID], [t1].[ID]

How can I force an INNER JOIN instead of the LEFT OUTER JOIN? Am I modeling my relationship incorrectly on the backend?

Thanks for any help.

MMAS

Answer 1

LINQ to SQL generates the LEFT OUTER JOIN simply because UserPermissions.RelatedUserID column is nullable. The underlying LINQ provider just isn’t ‘smart’ enough to further optimize that query to a simple INNER JOIN. I don’t think there is anything you can do about this.