EF Core materializes projection property as object with default values

I have a LINQ expression like the following:

from u in Context.Users.Where(u => u.Id == 123).Select(UserDto.Map)
join l in Context.Locations.Select(LocationDto.Map) on u.LocationId equals l.Id into locations
from l in locations.DefaultIfEmpty()
join a in Context.Agencies.Select(AgencyDto.Map) on l.CompanyId equals a.Id into agencies
from a in agencies.DefaultIfEmpty()
join m in Context.Markets.Select(MarketDto.Map) on l.CompanyId equals m.Id into markets
from m in markets.DefaultIfEmpty()
select new UserEntityData {
   User = u,
   Location = l,
   Agency = a,
   Market = m
}

User via Location can be connected to Agency or Market, not both. EF translates it correctly into SQL query with left joins. Query returns correct data with Agency or Market columns all NULL. However when query data is materialized I get UserEntityData objects with both Agency and Market properties not null. UserEntityData property for missing DB record is initialized with object with default values. I expect property to be null.

May be usefull:

1. If I read full entities for agency\market (not projected DTOs) all works fine.
2. I tried EF Core 5\6 and got another error ‘Nullable object must have a value’ during materialization. Looks like EF tries to put NULLs from DB response into not-nullable properties of my DTOs.

Project to reproduce the original issue: EfTest.zip

EF Core version: 3.1.15 Database provider: Microsoft.EntityFrameworkCore.SqlServer Target framework: .Net Framework 4.8

[smitpatel]

It is same. Refer to this comment https://github.com/dotnet/efcore/issues/22517#issuecomment-692236476

[Alexander-Leontiev]

@smitpatel are you sure it’s the same thing? From https://github.com/dotnet/efcore/issues/22517: “confirmed this works in 3.1, but fails in latest daily” - my example fails in 3.1 also.