Include / ThenInclude with where in EF Core

Question

I need to use where in ThenInclude

        var templatesFields = await _context.Sections
        .Include(x => x.Subtitles)
        .ThenInclude(r => r.Fields.Where(t=>t.TemplatesFields.TemplateID==TemplateID))
        .ThenInclude(r => r.OptionSources)
        .ThenInclude(r => r.OptionsSourcesDetails)
        .ToListAsync();

Answer 1

you cannot use where condition inside Include or ThenInclude. What you can do is:

var templatesFields = await _context.Sections
    .Include(x => x.Subtitles)
    .ThenInclude(r => r.Fields)
    .ThenInclude(r => r.OptionSources)
    .ThenInclude(r => r.OptionsSourcesDetails)
    .Where(t=>t.Subtitles.Fields.Any(x => x.TemplatesFields.TemplateID==TemplateID))
    .ToListAsync();

EDIT: This will be possible with .Net Core 5.0 (which is in preview right now)

var blogs = context.Blogs
    .Include(e => e.Posts.Where(p => p.Title.Contains("Cheese")))
    .ToList();

Filtered Include