Manually select related table data (SELECT N + 1 problem) LINQ to SQL

Question

Database example:

Image - ImageTag - Tag

Images can have multiple tags. The relationships are set up fine and stuff but I am running into pe

Answer 1

You can use the DataLoadOptions class to load related objects with a query.

DataLoadOptions dlo = new DataLoadOptions();

dlo.LoadWith<Image>(image => image.ImageTags);
dlo.LoadWith<ImageTag>(imageTag => imageTag.Tags);

context.DataLoadOptions = dlo;

Just to mention - this is called the "SELECT N + 1 problem".

UPDATE

I am usually using LINQ to Entities and have not much experience with LINQ to SQL. It might be required to disable DeferredLoadingEnabled explicitly, too.

context.DeferredLoadingEnabled = false;

Answer 2

why not try something like:

return
        from i in qry
        from iTags in i.ImageTags
        where tags.Contains(iTags.Tag)
        select new { TagName = i.Tag.name };

That will return a Collection with only the Tag Names. I hope I'm understanding your question properly here. Hope it helps