C#•9mo ago

[EF Core/LINQ] Paginated Eager-Loaded One-to-Many

I can't seem to find (maybe my Googling is bad) the proper way - if it's possible - to limit the returns of an eager-loaded one-to-many collection.

var form = DbContext.Forms
  .Find(1)
  .Include(form => form.Submission);

var form = DbContext.Forms
  .Find(1)
  .Include(form => form.Submission);

In my case a form could have millions of them - is it possible to limit the data fetched via .Include()? Similar to how Take() and Skip() work on the main query?

2 Replies

Angius•9mo ago

You should not be using .Include() and this is one of the reasons .Select() gives you much more control

var form = await _context.Forms
    .Where(f => f.Id == id)
    .Select(f => new FormDto {
        Id = f.Id,
        Title = f.Title,
        // other props...
        Submissions = f.Submissions
            .Skip(skip)
            .Take(take)
            .Select(s => new SubmissionDto {
                // ...
            })
            .ToList(),
        // other props...
    })
    .FirstOrDefaultAsync();

var form = await _context.Forms
    .Where(f => f.Id == id)
    .Select(f => new FormDto {
        Id = f.Id,
        Title = f.Title,
        // other props...
        Submissions = f.Submissions
            .Skip(skip)
            .Take(take)
            .Select(s => new SubmissionDto {
                // ...
            })
            .ToList(),
        // other props...
    })
    .FirstOrDefaultAsync();

nox7OP•9mo ago

Sorry for the late reply - but I see now. Thanks

Gaming

Programming

[EF Core/LINQ] Paginated Eager-Loaded One-to-Many