Query: Exception when filtering on nullable boolean value (through navigation property)

[AustinFelipe]

I'm trying to figure out why the following command doesn't work:

var availability = await context.UserAvailabilities
    .Where(t => t.User.Id == user.Id && t.User.IsProfessional)
    .ToListAsync();

I'm getting this error (Sorry about the size...):

An unhandled exception has occurred while executing the request System.ArgumentException: Expression of type 'System.Func2[Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor+TransparentIdentifier2[Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor+TransparentIdentifier2[UPlatform.Models.UserAvailability,System.Collections.Generic.IAsyncEnumerable1[UPlatform.Models.ApplicationUser]],UPlatform.Models.ApplicationUser],System.Nullable1[System.Boolean]]' cannot be used for parameter of type 'System.Func2[Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor+TransparentIdentifier2[Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor+TransparentIdentifier2[UPlatform.Models.UserAvailability,System.Collections.Generic.IAsyncEnumerable1[UPlatform.Models.ApplicationUser]],UPlatform.Models.ApplicationUser],System.Boolean]' of method 'System.Collections.Generic.IAsyncEnumerable1[Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor+TransparentIdentifier2[Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor+TransparentIdentifier2[UPlatform.Models.UserAvailability,System.Collections.Generic.IAsyncEnumerable1[UPlatform.Models.ApplicationUser]],UPlatform.Models.ApplicationUser]] _Where[TransparentIdentifier2](System.Collections.Generic.IAsyncEnumerable1[Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor+TransparentIdentifier2[Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor+TransparentIdentifier2[UPlatform.Models.UserAvailability,System.Collections.Generic.IAsyncEnumerable1[UPlatform.Models.ApplicationUser]],UPlatform.Models.ApplicationUser]], System.Func2[Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor+TransparentIdentifier2[Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor+TransparentIdentifier2[UPlatform.Models.UserAvailability,System.Collections.Generic.IAsyncEnumerable1[UPlatform.Models.ApplicationUser]],UPlatform.Models.ApplicationUser],System.Boolean])'

I thought it was because the table is empty and there is some problem when I'm trying to use the t.User property, but isn't. Wherever I try to access the User property reference, I get this error.

This strange behaviour starts when I updated to 1.0.0-rc2 versions.

If I remove the Where clausure, it works:

var availability = await context.UserAvailabilities.ToListAsync();

I already tried to replace ToListAsync() by ToList(), but I'm getting the same error.

Any help will be welcome. 👍

Thanks

[maumar]

@AustinFelipe could you provide some more info about the entities and DbContext you are using (specifically contents of class User, UserAvailability and OnModelCreating method of the DbContext)

[AustinFelipe]

@maumar They are:

public class ApplicationUser : IdentityUser
    {
        public string Name { get; set; }

        public bool IsProfessional { get; set; }

        public string PictureUrl { get; set; }

        public Genre Genre {
            get
            {
                return (Genre)GenreIdentifier;
            }
            set
            {
                GenreIdentifier = (int)value;
            }
        }

        public int GenreIdentifier { get; set; }

        /* Profile */
        public string AboutMe { get; set; }

        public ICollection<UserSpecialization> UserSpecs { get; set; }

        public ICollection<UserResumeEntry> Resume { get; set; }

        public ICollection<UserComment> Comments { get; set; }

        public ICollection<UserTimetable> Timetable { get; set; }

        public ICollection<UserAvailability> Availability { get; set; }
   }

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

        public int Day { get; set; }

        public string Hours { get; set; }

        public ApplicationUser User { get; set; }
    }

public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
    {
        public DbSet<Specialization> Specializations { get; set; }
        public DbSet<Package> Packages { get; set; }
        public DbSet<ChatMessage> ChatMessages { get; set; }
        public DbSet<UserComment> UserComments { get; set; }
        public DbSet<UserResumeEntry> UserResumes { get; set; }
        public DbSet<UserTimetable> UserTimetables { get; set; }
        public DbSet<UserAvailability> UserAvailabilities { get; set; }
        public DbSet<UserVacation> UserVacations { get; set; }
        public DbSet<Transaction> Transactions { get; set; }
        public DbSet<TransactionItem> TransactionItems { get; set; }

        public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
            : base(options)
        {
        }

        protected override void OnModelCreating(ModelBuilder builder)
        {
            base.OnModelCreating(builder);

            builder.Entity<UserSpecialization>()
                .HasKey(t => new { t.ApplicationUserId, t.SpecializationId });

            builder.Entity<ApplicationUser>()
                .HasMany(t => t.Comments)
                .WithOne(t => t.User);

            builder.Entity<ApplicationUser>()
                .HasMany(t => t.Timetable)
                .WithOne(t => t.User);

            builder.Entity<ApplicationUser>()
                .Ignore(t => t.Genre);

            builder.Entity<UserComment>()
                .HasOne<ApplicationUser>(t => t.Client);

            builder.Entity<UserTimetable>()
                .HasOne<ApplicationUser>(t => t.Client);

            builder.Entity<Transaction>()
                .HasOne<ApplicationUser>(t => t.Buyer);

            builder.Entity<Transaction>()
                .HasOne<ApplicationUser>(t => t.Seller);

            builder.Entity<UserTimetable>()
                .HasOne<Transaction>(t => t.Transaction);
        }

Let me know if you need something

[maumar]

@AustinFelipe the workaround is as follows:

var availability = await context.UserAvailabilities
    .Where(t => t.User.Id == user.Id && t.User.IsProfessional == true)
    .ToList();

if that doesn't work you can also try:

var availability = await context.UserAvailabilities
    .Where(t => t.User.Id == user.Id && ((bool?)t.User.IsProfessional) == true)
    .ToList();

The reason is that, since User is optional navigation and the result can be null, we are trying to compensate for that by casting non-nullable value types to their nullable version (so that in case User is null, we can return a null for the IsProfessional as well). In some cases we can be smart enough so that the process in transparent to the end user (and hopefully case will be transparent also), but sometimes users need to compensate for it manually. Good example would be projecting optional value into anonymous type:

var availability = await context.UserAvailabilities
    .Select(t => new { foo = t.User.IsProfessional })
    .ToList();

will throw and we can't do anything about it, so it needs to be changed to:

var availability = await context.UserAvailabilities
    .Select(t => new { foo = (bool?)t.User.IsProfessional })
    .ToList();

[divega]

I think this is important still because it happens for a simple query and although the workaround (adding == true) looks simple enough once you know it, it is hard to imagine customers arriving to it.

From another perspective it looks lower priority than other RTM bugs.

@rowanmiller I have asked @maumar to still try to get a fix for this in but #3807 seems higher priority. Thoughts?

[maumar]

Actually, this seems to be a duplicate of #4753 (scheduled for 1.0.1 currently)

[AustinFelipe]

@maumar Yeah, I changed it and it's working now.

var availability = await context.UserAvailabilities
    .Where(t => t.User.Id == user.Id && t.User.IsProfessional == true)
    .ToListAsync();

Btw, I agree with @divega, it's hard to figure out, isn't it?

But, thanks man, it's working now 👍

[rowanmiller]

@rowanmiller I have asked @maumar to still try to get a fix for this in but #3807 seems higher priority. Thoughts?

Agreed

[maumar]

fixed in 7fe8981

[gdoron]

@maumar which means it's fixed for 1.0.0, right?
How the versions and milestones work now?

[maumar]

@gdoron unfortunately by the time I got around to making the fix, RTM was pretty much locked for development, apart from security issues and ship stoppers. So this fix will actually be available in post RTM release. You can see the list of commits for RTM here:
https://github.com/aspnet/EntityFramework/commits/release

dev branch is not for post RTM development