"Argument types do not match" when using cast in where clause

[genne]

I've been trying to migrate from EF 6 to EF core, but can't figure out how to handle this case (simplified example, see full example below):

myContext.Blogs.Select(blog => new BlogDto()
{
  Id = blog.Id,
  Post = blog.Posts.FirstOrDefault(),
})
.Where(s => ((IEntity) s).Id == 1)
.Select(p => p.Id)

When running I get the following exception (unfortunately exception message is in Swedish, but should be same as "Argument types do not match"):

System.ArgumentException
  HResult=0x80070057
  Message=Argumenttyperna matchar inte
  Source=System.Core
  StackTrace:
   at System.Linq.Expressions.Expression.Bind(MemberInfo member, Expression expression)
   at System.Linq.Expressions.MemberAssignment.Update(Expression expression)
   at System.Linq.Expressions.ExpressionVisitor.VisitMemberAssignment(MemberAssignment node)
   at System.Linq.Expressions.ExpressionVisitor.VisitMemberBinding(MemberBinding node)
   at System.Linq.Expressions.ExpressionVisitor.Visit[T](ReadOnlyCollection`1 nodes, Func`2 elementVisitor)
   at System.Linq.Expressions.ExpressionVisitor.VisitMemberInit(MemberInitExpression node)
   at System.Linq.Expressions.MemberInitExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at System.Linq.Expressions.ExpressionVisitor.VisitUnary(UnaryExpression node)
   at System.Linq.Expressions.UnaryExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at System.Linq.Expressions.ExpressionVisitor.VisitMember(MemberExpression node)
   at Microsoft.EntityFrameworkCore.Query.ExpressionVisitors.RelationalEntityQueryableExpressionVisitor.VisitMember(MemberExpression node)
   at System.Linq.Expressions.MemberExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at System.Linq.Expressions.ExpressionVisitor.VisitBinary(BinaryExpression node)
   at System.Linq.Expressions.BinaryExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor.ReplaceClauseReferences(Expression expression, IQuerySource querySource, Boolean inProjection)
   at Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor.VisitWhereClause(WhereClause whereClause, QueryModel queryModel, Int32 index)
   at Microsoft.EntityFrameworkCore.Query.RelationalQueryModelVisitor.VisitWhereClause(WhereClause whereClause, QueryModel queryModel, Int32 index)
   at Remotion.Linq.Clauses.WhereClause.Accept(IQueryModelVisitor visitor, QueryModel queryModel, Int32 index)
   at Remotion.Linq.QueryModelVisitorBase.VisitBodyClauses(ObservableCollection`1 bodyClauses, QueryModel queryModel)
   at Remotion.Linq.QueryModelVisitorBase.VisitQueryModel(QueryModel queryModel)
   at Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor.VisitQueryModel(QueryModel queryModel)
   at Microsoft.EntityFrameworkCore.Query.RelationalQueryModelVisitor.VisitQueryModel(QueryModel queryModel)
   at Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor.CreateQueryExecutor[TResult](QueryModel queryModel)
   at Microsoft.EntityFrameworkCore.Storage.Database.CompileQuery[TResult](QueryModel queryModel)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.CompileQueryCore[TResult](Expression query, IQueryModelGenerator queryModelGenerator, IDatabase database, IDiagnosticsLogger`1 logger, Type contextType)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<>c__DisplayClass13_0`1.<Execute>b__0()
   at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQueryCore[TFunc](Object cacheKey, Func`1 compiler)
   at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQuery[TResult](Object cacheKey, Func`1 compiler)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.Execute[TResult](Expression query)
   at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.Execute[TResult](Expression expression)
   at Remotion.Linq.QueryableBase`1.GetEnumerator()
   at System.Linq.Buffer`1..ctor(IEnumerable`1 source)
   at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
   at EFSampleApp.Program.Main()

If I comment out any of the above lines in the code above it works, also if I avoid casting to IEntity in the Where clause.

(The actual code is a lot more complex, and I know this particular example could be simplified a lot, but we're using generic helper methods that does most of this for us, and I would like to keep it that way. The example code is just to reproduce the exception.)

Steps to reproduce

using System.Collections.Generic;
using System.Linq;
using Microsoft.EntityFrameworkCore;

namespace EFSampleApp
{
    public class Program
    {
        public static void Main()
        {
            var myContext = new MyContext();
            myContext.Database.EnsureDeleted();
            myContext.Database.EnsureCreated();
            var blogs = myContext.Blogs.Select(blog => new BlogDto()
                {
                    Id = blog.Id,
                    Post = blog.Posts.FirstOrDefault(),
                })
                .Where(s => ((IEntity) s).Id == 1)
                .Select(p => p.Id)
                .ToArray();
        }
    }
    public class MyContext : DbContext
    {
        // Declare DBSets
        public DbSet<Blog> Blogs { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            optionsBuilder
                .UseSqlServer(
                    @"Server=(localdb)\mssqllocaldb;Database=_ModelApp;Trusted_Connection=True;Connect Timeout=5;ConnectRetryCount=0")
                .EnableSensitiveDataLogging();
        }
    }

    public interface IEntity
    {
        int Id { get; }
    }

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

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

    public class BlogDto : IEntity
    {
        public int Id { get; set; }
        public Post Post { get; set; }
    }
}

Further technical details

EF Core version: 2.1.2.0
Database Provider: Microsoft.EntityFrameworkCore.SqlServer
Operating system: Windows 10
IDE: Visual Studio 2017 15.8.1

[smitpatel]

Error in 3.1

Unhandled exception. System.InvalidOperationException: The LINQ expression 'DbSet<Blog>                                                                                                                                                                                                                                  
    .Where(b => ((IEntity)new BlogDto{                                                                                                                                                                                                                                                                                   
        Id = b.Id,                                                                                                                                                                                                                                                                                                       
        Post = DbSet<Post>                                                                                                                                                                                                                                                                                               
            .Where(p => EF.Property<Nullable<int>>(b, "Id") != null && EF.Property<Nullable<int>>(b, "Id") == EF.Property<Nullable<int>>(p, "BlogId"))                                                                                                                                                                   
            .FirstOrDefault()                                                                                                                                                                                                                                                                                            
    }                                                                                                                                                                                                                                                                                                                    
    ).Id == 1)' could not be translated. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to either AsEnumerable(), AsAsyncEnumerable(), ToList(), or ToListAsync(). See https://go.microsoft.com/fwlink/?linkid=2101038 for more information.   

We should try to fix this.

[smitpatel]

Duplicate of #20097