I upgraded from .NET 5 to .NET 6 and now getting SqlNullValueException from a LINQ query-CodePudding

I just upgraded a project from .NET 5 to the .NET 6 preview and started using Visual Studio 2022. But I'm getting a SqlNullValueException that I wasn't getting before. And it's not making sense to me.

Here is the LINQ query:

var clients = _dbContext.AppUserAppUsers
            .Where(x => x.AppUserParentId == designerId
                        && x.ChildAppUser.AppUserRole == AppUserRole.Client)
            .Include(x => x.ChildAppUser.Profile)
            .Select(x => x.ChildAppUser)
            .AsNoTracking();

return clients.ToList();

The AppUserAppUsers entity is a many-to-many model for AppUsers. I'm using the Table-per-hierarchy pattern So I have AppUserBase abstract class and DesignerModel and ClientModel both extend that class.

public class AppUserAppUser
    {
        public int AppUserParentId { get; set; }

        public int AppUserChildId { get; set; }

        public bool Active { get; set; }

        public AppUserBase ParentAppUser { get; set; }

        public AppUserBase ChildAppUser { get; set; }
    }

Again, all this works beautifully in .NET 5!

The call to ToList() throws this exception:

System.Data.SqlTypes.SqlNullValueException
  HResult=0x80131931
  Message=Data is Null. This method or property cannot be called on Null values.
  Source=Microsoft.Data.SqlClient
  StackTrace:
   at Microsoft.Data.SqlClient.SqlBuffer.ThrowIfNull()
   at Microsoft.Data.SqlClient.SqlBuffer.get_String()
   at Microsoft.Data.SqlClient.SqlDataReader.GetString(Int32 i)
   at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.Enumerator.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at Design2WorkroomApi.Repository.AppUserRepository.GetClientsByDesignerId(Int32 designerId) in C:\Users\davew\source\repos\Design2WorkroomApi\Design2WorkroomApi\Repository\AppUserRepository.cs:line 65
   at Design2ClientAPI.Controllers.ClientsController.GetClientsByDesignerId(Int32 designerId) in C:\Users\davew\source\repos\Design2WorkroomApi\Design2WorkroomApi\Controllers\ClientsController.cs:line 56
   at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.SyncActionResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeActionMethodAsync()
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeNextActionFilterAsync()

If I take out the Include and the Select calls this works fine. But either one and the LINQ statement returns null.

In the .NET 5 version, this same method with the same parameter works just fine. And I have used similar code many times before with no problems.

Obviously, something in .NET 6 has changed to cause this, but I don't know what it is.

Here are my Entity Framework Core packages. I had the same issue before I upgraded these packages.

 <PackageReference Include="Microsoft.AspNetCore.Identity.EntityFrameworkCore" Version="6.0.0-rc.2.21480.10" />
    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="6.0.0-rc.2.21480.5" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="6.0.0-rc.2.21480.5" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="6.0.0-rc.2.21480.5">

CodePudding user response：

Remove the .Include(), it is not needed in this particular case and it can cause the error which you are getting.

The new query should simply look something like:

var clients = _dbContext.AppUserAppUsers
            .Where(x => x.AppUserParentId == designerId
                        && x.ChildAppUser.AppUserRole == AppUserRole.Client)
            .Select(x => x.ChildAppUser)
            .AsNoTracking();