Array.Concat stopped working in EFCore8

[srasch]

I try to update some rows in the database using this Updatemethod:

await db.Test
    .Where(x => x.RoleId == 2)
    .ExecuteUpdateAsync(c => c.SetProperty(x => x.TextParts, x => x.TextParts.Concat(arr)));

or

  await db.Test
    .Where(x => x.RoleId == 1)
    .ExecuteUpdateAsync(c => c.SetProperty(x => x.TextParts, x => x.TextParts.Append("Foo")));

Both are working using EFCore7 and none are working in EFCore8
The error message for Concat is

InvalidOperationException: The LINQ expression 'DbSet<TestModel>()
    .Where(t => t.RoleId == 2)
    .ExecuteUpdate(c => c.SetProperty<IEnumerable<string>>(
        propertyExpression: x => x.TextParts, 
        valueExpression: x => x.TextParts
            .Concat(__arr_0)))' could not be translated. Additional information: Translation of method 'System.Linq.Enumerable.Concat' failed. If this method can be mapped to your custom function, see https://go.microsoft.com/fwlink/?linkid=2132413 for more information.
The following lambda argument to 'SetProperty' does not represent a valid value: 'x => x.TextParts
    .Concat(__arr_0)'. See https://go.microsoft.com/fwlink/?linkid=2101038 for more information.

and the message for Append:

InvalidOperationException: The LINQ expression 'DbSet<TestModel>()
    .Where(t => t.RoleId == 1)
    .ExecuteUpdate(c => c.SetProperty<IEnumerable<string>>(
        propertyExpression: x => x.TextParts, 
        valueExpression: x => x.TextParts
            .Append("Foo")))' could not be translated. Additional information: Translation of method 'System.Linq.Enumerable.Append' failed. If this method can be mapped to your custom function, see https://go.microsoft.com/fwlink/?linkid=2132413 for more information.
The following lambda argument to 'SetProperty' does not represent a valid value: 'x => x.TextParts
    .Append("Foo")'. See https://go.microsoft.com/fwlink/?linkid=2101038 for more information.

Here is a complete LinqPad-Script:

async Task Main()
{
  var db = new TestContext();

//  await db.Database.EnsureDeletedAsync();
  await db.Database.EnsureCreatedAsync();

  await db.Database.MigrateAsync();

  if (!await db.Test.AnyAsync())
  {
    await db.Test.AddRangeAsync(
      new TestModel { ProjectId = 1, RoleId = 1, },
      new TestModel { ProjectId = 1, RoleId = 2, },
      new TestModel { ProjectId = 2, RoleId = 1, },
      new TestModel { ProjectId = 2, RoleId = 2, TextParts = ["Hello"], },
      new TestModel { ProjectId = 3, }
    );
    await db.SaveChangesAsync();
  }
  
  string[] arr = [ "World" ];
  
  await db.Test
    .Where(x => x.RoleId == 2)
    .ExecuteUpdateAsync(c => c.SetProperty(x => x.TextParts, x => x.TextParts.Concat(arr)));

  await db.Test
    .Where(x => x.RoleId == 1)
    .ExecuteUpdateAsync(c => c.SetProperty(x => x.TextParts, x => x.TextParts.Append("Foo")));
}

public class TestModel
{
  public Guid Id { get; set; }
  public int ProjectId { get; set; }
  public int RoleId { get; set; }
  public string[] TextParts { get; set; }
}

public class TestContext : DbContext
{
  public DbSet<TestModel> Test { get; set; }

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

    modelBuilder.Entity<TestModel>()
      .HasIndex(x => x.Id);
  }
  protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
  {
    optionsBuilder
      .UseNpgsql("<DBCONNECTION>", o => o.SetPostgresVersion(16, 0))
      .LogTo(x => Console.WriteLine(x), new[] { new EventId(20101)});
    base.OnConfiguring(optionsBuilder);
  }
}

but not for EFCore8

the tested Nuget-Packages are:

Package	working	not working
Microsoft.EntityFrameworkCore	7.0.14	8.0.0
Microsoft.EntityFrameworkCore.Abstractions	7.0.14	8.0.0
Microsoft.EntityFrameworkCore.Relational	7.0.14	8.0.0
Newtonsoft.Json	13.0.3	13.0.3
Npgsql	7.0.6	8.0.0
Npgsql.EntityFrameworkCore.EFCore	7.0.11	8.0.0

[roji]

Thanks for filing this. It may take me a while before I'm able to investigate, but I'll definitely be looking into it.

[roji]

This turned out to be a bit of a rabbit hole... EF 8.0 got 1st-class support for queryable (primitive) collections, and so operators like Concat/Append are now handled via that "pipeline" (rather than as arbitrary method translations). However, there are various issues specifically with using queryable collections inside ExecuteUpdate - see dotnet/efcore#32494.

In the meantime I've submitted #3005 to bring back enumerable translations for Concat/Append specifically, for 8.0.1.

[srasch]

thank you so much for your fast investigation. 👍