Arrays of type with value converter fail in query generation about efcore.pg

[roji]

To be honest, I would have expected that defining a value converter for a given type would also convert (Postgres) arrays of that type.

You should indeed be defining a value converter on the element type of MyEnums, rather than a value converter for the entire array; once you do the latter, EF has no way of knowing what the actual internal representation is that's returned by your value converter, and so is unable to translate queries over it.

Try the following:

modelBuilder.Entity<MyModel>().PrimitiveCollection(b => b. MyEnums).ElementType().HasConversion(typeof(MyEnumValueConverter));

Let me know if that solves it for you. Unfortunately the EF docs are quite behind on these details...

[ffried]

@roji Thanks for the quick reply!

Try the following:

modelBuilder.Entity<MyModel>().PrimitiveCollection(b => b.MyEnums).ElementType().HasConversion(typeof(MyEnumValueConverter));

Thanks for the hint here - I really haven't seen the PrimitiveCollection API anywhere yet.
Unfortunately, it still doesn't work and it still uses the enum case name in the query:

Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (15ms) [Parameters=[@__myEnum_0='Case2' (Nullable = false)], CommandType='Text', CommandTimeout='30']
      SELECT m.id, m.my_enum, m.my_enums
      FROM my_model AS m
      WHERE m.my_enums @> ARRAY[@__myEnum_0]::varchar(16)[]

Here's the db context code I'm now using:

ApplicationDbContext.cs

public sealed class ApplicationDbContext(DbContextOptions<ApplicationDbContext> options) : DbContext(options)
{
    public DbSet<MyModel> MyModels { get; init; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        base.OnConfiguring(optionsBuilder);
        var dataSource = new NpgsqlDataSourceBuilder("Host=127.0.0.1:5432;Database=test;Username=postgres;Password=MySecretPwd");
        optionsBuilder.UseNpgsql(dataSource.Build())
            .EnableDetailedErrors()
            .EnableSensitiveDataLogging();
    }

    private sealed class MyEnumValueConverter() : ValueConverter<MyEnum, string>(
        e => e.GetString(),
        s => s.GetMyEnum()
    );

    protected override void ConfigureConventions(ModelConfigurationBuilder configurationBuilder)
    {
        base.ConfigureConventions(configurationBuilder);

        configurationBuilder.Properties<MyEnum>().HaveConversion<MyEnumValueConverter>();
    }

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

        modelBuilder.Entity<MyModel>(entity =>
        {
            entity.Property(e => e.MyEnum)
                .HasConversion<MyEnumValueConverter>();
            entity.PrimitiveCollection(e => e.MyEnums)
                .ElementType()
                .HasConversion<MyEnumValueConverter>();

            entity.HasData(new MyModel
            {
                Id = 1,
                MyEnum = MyEnum.Case3,
                MyEnums = [MyEnum.Case1, MyEnum.Case2],
            });
        });
    }
}

---

Btw. is this primitive collection configuration also possible via conventions? In my original project we're configuring these enums via an attribute where we then configure the enums with that attribute in the ConfigureConventions method.

[snebjorn]

I got this working using the PrimitiveCollection trick :)
EF support enums as strings. I got it working using

modelBuilder.Entity<MyModel>().PrimitiveCollection(b => b.MyEnums).ElementType().HasConversion<string>();

I tested this query and it worked!

_context.Foos.Where(x => x.MyEnums.Contains(MyEnum.Foo))

Thank you!

[ffried]

It seems to work with the default EnumToStringConverter (which is what HasConversion<string>() uses according to the docs). But custom converters seem to be ignored at least partially. My HasData call seems to use it, but the query generated by the controller call doesn't.