EF Core 3, optimize lots of Include/ThenInclude

Question

I have a query like this

return await _ctx.Activities
            .Include(a => a.Attributes)
            .Include(a => a.Roles)
            .Include(a         


        

Answer 1

You'll want to split it into multiple queries, to speed up the performance. You can use explicit loading for this. It's not the prettiest solution, but it works. Hopefully an easier solution will come in EF 5.

I'm guessing a bit on which fields are collections and which are "normal" entries, but something like this:

var activity = await _ctx.Activities.FindAsync(Id);

await context.Entry(activity)
    .Collection(a => a.Attributes)
    .LoadAsync();

await context.Entry(activity)
    .Collection(a => a.Roles)
    .LoadAsync();

await context.Entry(activity)
    .Collection(a => a.Bookmarks)
    .LoadAsync();

await context.Entry(activity)
    .Collection(a => a.VideoMetas)
    .Query()
    .Include(vm => vm.Instances)
    .LoadAsync();

await context.Entry(activity)
    .Collection(a => a.ImageMetas)
    .Query()
    .Include(im => im.Instances)
    .LoadAsync();

await context.Entry(activity)
    .Reference(a => a.Procedure)
    .Query()
    .Include(p => p.Attributes)
    .LoadAsync();

return activity;