Question

I have the following query:

var content = (from ca in db.ContentAccesses 
               where !candidateList.Contains(ca.Content) &&
                     ca.DateAccessed >= DateTime.Now.AddDays(-90)
               group ca by ca.ContentId)
               .OrderByDescending(c => c.Count()).Take(5);

Which is resolving to the following T-SQL

SELECT TOP (5) [t1].[ContentId] AS [Key]
FROM (
    SELECT COUNT(*) AS [value], [t0].[ContentId]
    FROM [dbo].[ContentAccesses] AS [t0]
    WHERE (NOT ([t0].[ContentId] = @p0)) AND ([t0].[DateAccessed] >= @p1)
    GROUP BY [t0].[ContentId]
    ) AS [t1]
ORDER BY [t1].[value] DESC

But I need the actual “Content” objects, not just the ContentId’s… so I’ve tried adding select ca.Content after the group by but compiler will complain.

ContentAcceses has a FK (ContentId) to Content table.

I don’t understand LINQ quite well yet.

Answer 1

You need to flatten the groupings down to get the individual objects from the group. However since you wanted to group each ContentAccess‘s Content, you should group by that as well.

var content = (from ca in db.ContentAccesses 
               where !candidateList.Contains(ca.Content)
                  && ca.DateAccessed >= DateTime.Now.AddDays(-90)
               group ca by ca.ContentId into g
               orderby g.Count() descending
               from ca in g        // flatten the group
               select ca)
              .Take(5);

For the sake of having a simpler equivalent TSQL query, you might want to use LINQ to Objects to do the flattening and get the first 5.

var content = (from ca in db.ContentAccesses 
               where !candidateList.Contains(ca.Content)
                  && ca.DateAccessed >= DateTime.Now.AddDays(-90)
               group ca by ca.ContentId into g
               orderby g.Count() descending
               select g)
              .AsEnumerable()     // use LINQ to Objects
              .SelectMany(g => g) // flatten the group
              .Take(5);