Efcore: No way to .ThenInclude() multiple sub-properties

[gzak]

Suppose I have the following entities:

public class A
{
    public int Id { get; set; }
    public int BId { get; set; }
    public virtual B B { get; set; }
}

public class B
{
    public int Id { get; set; }
    public int C1Id { get; set; }
    public int C2Id { get; set; }
    public virtual C C1 { get; set; }
    public virtual C C2 { get; set; }
}

public class C
{
    public int Id { get; set; }
}

Now suppose I want to retrieve all A's and include their B's and both of B's C sub-properties.

I can do db.A.Include(a => a.B).ThenInclude(b => b.C1) to include one of B's C sub-properties, but as far as I can tell, there's no way to include both of B's C sub-properties. If I tack on another .Include(), I'm dealing with A's. If I tack on anther .ThenInclude(), I'm now dealing with C's. There's no way to deal with B's beyond the first call to .ThenInclude().

I propose that the IIncludableQueryable interface should also expose an .AndInclude() method, which can be tacked onto a call to .ThenInclude() to continue accessing the associated property.

[rowanmiller]

Here is what you are after...

 db.A
    .Include(a => a.B).ThenInclude(b => b.C1)
    .Include(a => a.B).ThenInclude(b => b.C2)

BTW because these are reference (and not collection) properties, you can do this for short. ThenInclude only becomes mandatory when you want to include after a collection navigation property.

 db.A
    .Include(a => a.B.C1)
    .Include(a => a.B.C2)

[rowanmiller]

BTW https://github.com/aspnet/EntityFramework/issues/4490 "More flexible Include API - allow walking back up include tree" is also relevant to this code.

[gzak]

Thanks @rowanmiller, makes sense to me. I was about to try the former approach, but the latter one is more compact so I'll switch to that. Feel free to close this issue if appropriate.

[Waldspecht]

Is there any restriction on how deep you can go with ThenInclude?
Because up to level three (Info)everything works fine. When I include level four (Details) it is not returned or included as an object.

Company company = _context.Companies
                 .Include(c => c.Users)
                 .Include(c => c.Projects)
                     .ThenInclude(p => p.Specifications)
                        .ThenInclude(spec => spec.Info)
                            .ThenInclude(info => info.Details)
                 .Include(c => c.Projects)
                     .ThenInclude(p => p.Specifications)
                        .ThenInclude(spec => spec.Files)
                .Where(t => t.CompanyId.Equals(companyId))
                 .FirstOrDefault();

The details objects are missing in the query and not returned. Any idea?

[yeganehaym]

it would be great this substitute syntax instead of repeat one thing consecutively
return _cart .Include(x => x.GameItems) .ThenInclude(x=>x.Game) .ThenInclude(x=>new{x.League,x.Host,x.Guest}) .AsQueryable();

instead of
`
return _cart
.Include(x => x.GameItems)
.ThenInclude(x=>x.Game)
.ThenInclude(x=>x.League)

            .Include(x => x.GameItems)
            .ThenInclude(x=>x.Game)
            .ThenInclude(x=>x.Host)

            .Include(x => x.GameItems)
            .ThenInclude(x=>x.Game)
            .ThenInclude(x=>x.Guest)
            .AsQueryable();

`
it's more comprehensible and shorter and easier

[marc9ot]

After doing this how exactly would I get a where condition from either C1 or C2? seems not to work when I try it with my repository pattern and EF6. Any leads here?

db.A .Include(a => a.B.C1) .Include(a => a.B.C2)

[eltiare]

I also get errors when I try to use this code in EF Core:

db.A
    .Include(a => a.B.C1)
    .Include(a => a.B.C2)

I keep seeing this method mentioned, yet have never gotten it to work.

[madhusudhan-v]

include theinclude both works fine... b ut only problem is intellisense not identifying or showing the methods just type and then proceed all works fine ...
var res = await _context.Diseases.Include(x => x.Disease2Symptom) .ThenInclude(z => z.Symptom).ToListAsync();

[sumiflow]

include theinclude both works fine... b ut only problem is intellisense not identifying or showing the methods just type and then proceed all works fine ...
var res = await _context.Diseases.Include(x => x.Disease2Symptom) .ThenInclude(z => z.Symptom).ToListAsync();

Thanks. It took me a long time to realize that what I was trying to do was perfectly valid but that it just wasn't showing in intellisense. I should have just typed it anyway.

Example:
intellisense works fine here:

from q in db.SecurityGroupPermissions
    .Include(x => x.SecurityAction)

intellisense does not work on the last item here. A list will pop up but it won't have SecurityAction in the popup:

from q in db.SecurityGroups
    .Include(x => x.SecurityGroupPermissions)
    .ThenInclude(x => x.SecurityAction)

Once I ignored intellisense and typed it out anyway then it built and ran correctly.

[ErroneousFatality]

Any news whether "Include.ThenInclude.AlsoInclude" syntax or similar will be implemented for a more elegant solution to this problem?

[deadmann]

It could change to IncludeSibling() or SisterInclude()...