Expression of type 'System.Object' cannot be used for parameter of type 'Microsoft.EntityFrameworkCore.Metadata.IEntityType'

[dannythomas13]

Since updating to v2 I now get the following exception from one of my unit tests:

System.ArgumentException : Expression of type 'System.Object' cannot be used for parameter of type 'Microsoft.EntityFrameworkCore.Metadata.IEntityType' of method 'Void StartTracking(System.Object, Microsoft.EntityFrameworkCore.Metadata.IEntityType)'
Parameter name: arg1

In order to get the test to pass I have had to change:

var projects = this.context.Projects
                        .Include(p => p.Windfarm)
                        .Include(p => p.Turbines)
                        .Where(p => p.Windfarm.ClientId == clientId && p.IsActive)
                        .GroupBy(g => g.WindfarmId)
.Select(s => s.OrderByDescending(o => o.DateStarted).FirstOrDefault())
                        .ToList();

to the following:

var activeProjects = this.context.Projects
                        .Include(p => p.Windfarm)
                        .Include(p => p.Turbines)
                        .Where(p => p.Windfarm.ClientId == clientId && p.IsActive)
                        .GroupBy(g => g.WindfarmId).ToList();

            var projects = activeProjects.Select(s => s.OrderByDescending(o => o.DateStarted).FirstOrDefault())
                        .ToList();

[smitpatel]

Repro

    public class Program
    {
        public static void Main(string[] args)
        {
            using (var db = new MyContext())
            {
                // Recreate database
                db.Database.EnsureDeleted();
                db.Database.EnsureCreated();

                // Seed database
                db.AddRange(
                    new Blog
                    {
                        Posts = new List<Post>
                        {
                            new Post(),
                            new Post(),
                            new Post()
                        }
                    },
                    new Blog
                    {
                        Posts = new List<Post>
                        {
                            new Post(),
                            new Post(),
                            new Post()
                        }
                    }
                    );


                db.SaveChanges();
            }

            using (var db = new MyContext())
            {
                // Run queries
                var query = db.Set<Post>()
                    .Include(p => p.Blog)
                    .GroupBy(p => EF.Property<int?>(p, "BlogId"))
                    .Select(g => g.OrderBy(e => e.Id).FirstOrDefault()).ToList();
            }

            Console.WriteLine("Program finished.");
        }
    }


    public class MyContext : DbContext
    {
        // Declare DBSets
        public DbSet<Blog> Blogs { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            // Select 1 provider
            optionsBuilder
                .UseSqlServer(@"Server=(localdb)\mssqllocaldb;Database=_ModelApp;Trusted_Connection=True;Connect Timeout=5;ConnectRetryCount=0")
                //.UseSqlite("filename=_modelApp.db")
                //.UseInMemoryDatabase(databaseName: "_modelApp")
                .EnableSensitiveDataLogging()
                .UseLoggerFactory(new LoggerFactory().AddConsole());
        }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            // Configure model
        }
    }

    public class Blog
    {
        public int Id { get; set; }
        public List<Post> Posts { get; set; }
    }

    public class Post
    {
        public int Id { get; set; }
        public Blog Blog { get; set; }
    }

[smitpatel]

Include with GroupBy and Select with single result operator.
This is regression from 1.1.2
@anpete

[smitpatel]

@maumar this bug!

[Cowlephant]

Just when I thought I might have gotten through with migrating to 2.0.. .more Entity Framework regressions.

Back to 1.x I go I suppose.

[dannythomas13]

@twilliamsgsnetx i'm also disappointed that I have had to retest my entire code base because this has affected a few places but I wouldn't be so hasty as to roll back, especially if you've already done the hard part of migrating. I would suggest simply using ef to do the selects but for any grouping operations do that after you have called toList

[maumar]

Problem is that when we apply Include on the selector, need to special case group by (apply include on element selector, rather than on qsre directly) - this logic is located in QueryModelExtensions.GetOutputExpression

However, for more complex scenarios the logic is not correct, as we only look at the top level query model and top level expression type to determine whether we are dealing with GroupBy query. In the problematic case group by is "hidden" in a subquery.

Workaround: add ToList() after GroupBy call, there is no perf hit, since (in 2.0) everything after Groupby is performed on the client anyway