Error when setting indexerProperties dictionary

[YeskaNova]

This regression happens if we want to set the dictionary of indexer properties to a tracked entity :

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

public class User
{
    public int Id { get; set; }
    public Dictionary<string, object> Data { get; set; }
}

public class SqliteDbContext : DbContext
{
    public SqliteDbContext(DbContextOptions options) : base(options)
    {
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        var etb = modelBuilder.Entity<User>();
        etb.Property(x => x.Id).UseHiLo("Hilo_User");
        etb.OwnsOne(x => x.Data, x =>
        {
            x.IndexerProperty(typeof(string), "a").IsRequired(false);
            x.IndexerProperty(typeof(string), "b").IsRequired(false);
            x.Property<int>("UserId").UseHiLo("Hilo_User");
        });
    }
}

class Program
{
    static void Main(string[] args)
    {
        var sc = new ServiceCollection();
        var guid = Guid.NewGuid();
        sc.AddDbContext<SqliteDbContext>(op => op.UseSqlServer(@"Server=(localdb)\MSSQLLocalDB;Integrated Security=true;DataBase=" + guid));
        using (var provider = sc.BuildServiceProvider())
        {
            using (var scope = provider.CreateScope())
            using (var dbcontext = scope.ServiceProvider.GetService<SqliteDbContext>())
            {
                dbcontext.Database.EnsureCreated();
            }
            var user = new User();
            using (var scope = provider.CreateScope())
            using (var dbcontext = scope.ServiceProvider.GetService<SqliteDbContext>())
            {
                dbcontext.Set<User>().Add(user);
                dbcontext.SaveChanges();
            }
            using (var scope = provider.CreateScope())
            using (var dbcontext = scope.ServiceProvider.GetService<SqliteDbContext>())
            {
                var u2 = dbcontext.Set<User>().First(x => x.Id == user.Id);
                u2.Data  = new Dictionary<string, object>(){{"a","test"},{"b","test"}};
                dbcontext.SaveChanges();
            }
        }

    }
}

Exception

System.InvalidOperationException: 'The property 'UserId' on entity type 'Dictionary<string, object>' is part of a key and so cannot be modified or marked as modified. To change the principal of an existing entity with an identifying foreign key first delete the dependent and invoke 'SaveChanges' then associate the dependent with the new principal.'

Further technical details

EF Core version: 5.0.0-rc.1.20378.4
Database provider: Microsoft.EntityFrameworkCore.SqlServer
Target framework: .NET Core 5.0
Operating system: Windows
IDE: Visual Studio 2019

[AndriySvyryd]

@YeskaNova You need to preserve the key value for UserId on Data

[YeskaNova]

@AndriySvyryd You say "preserve" but Data is null before I set it:

It works If I change the code to

                u2.Data  = new Dictionary<string, object>(){{"UserId", u2.Id}, {"a","test"},{"b","test"}};

but it's a clear regression to me. I think that this should be handled under the hood by EF, we shouldn't handle ( or expose ) internal keys.

[ajcvickers]

@YeskaNova When you say this is a regression, from which version has the behavior regressed here?

[YeskaNova]

@ajcvickers It regressed after 5.0.0-rc.1.20372.13 ( it works in that version, but not in the ones after it ).