[MEVD] Can't set IsAutoGenerated property of VectorStoreKeyAttribute at compile time

[adamsitnik]

The following code fails to compile:

[VectorStoreKey(StorageName = "name", IsAutoGenerated = true)]
public Guid Key { get; set; }

Because the IsAutoGenerated is bool?:

semantic-kernel/dotnet/src/VectorData/VectorData.Abstractions/RecordAttributes/VectorStoreKeyAttribute.cs

Line 30 in 082e28e

public bool? IsAutoGenerated { get; set; }

Which in C# maps to System.Nullable<bool> (a struct) and can't be set at compile time.

Could we make it just a bool like what it's mapped to at the end?

semantic-kernel/dotnet/src/VectorData/VectorData.Abstractions/ProviderServices/KeyPropertyModel.cs

Line 18 in 082e28e

public bool IsAutoGenerated { get; set; }

Context: https://github.com/dotnet/extensions/pull/7423/changes#r2974567816

cc @roji

[adamsitnik]

I've suggested Copilot to use following approach: a public bool property backed by an internal bool? property:

using System.Reflection;

namespace ConsoleApp15
{
    public class Program
    {
        static void Main()
        {
            TestAttribute setToTrue = typeof(Program).GetMethod(nameof(SetToTrue))!.GetCustomAttribute<TestAttribute>()!;
            Console.WriteLine($"IsAutoGenerated_Core for [Test(IsAutoGenerated = true)]: {setToTrue.IsAutoGenerated_Core}");

            TestAttribute setToFalse = typeof(Program).GetMethod(nameof(SetToFalse))!.GetCustomAttribute<TestAttribute>()!;
            Console.WriteLine($"IsAutoGenerated_Core for [Test(IsAutoGenerated = false)]: {setToFalse.IsAutoGenerated_Core}");

            TestAttribute notSet = typeof(Program).GetMethod(nameof(NotSet))!.GetCustomAttribute<TestAttribute>()!;
            Console.WriteLine($"IsAutoGenerated_Core for [Test]: {notSet.IsAutoGenerated_Core}");
        }

        [Test(IsAutoGenerated = true)]
        public static void SetToTrue() { }

        [Test(IsAutoGenerated = false)]
        public static void SetToFalse() { }

        [Test]
        public static void NotSet() { }
    }

    [AttributeUsage(AttributeTargets.All)]
    public class TestAttribute : Attribute
    {
        public bool IsAutoGenerated
        {
            get => throw new InvalidOperationException(); // provided to satisfy compiler requirements
            set => IsAutoGenerated_Core = value;
        }

        internal bool? IsAutoGenerated_Core { get; set; }
    }
}

[roji]

Hmm... the reason I made this bool? instead of bool was to let the provider decide whether that key type should be auto-generated by default or not... In other words, if it's just bool, then that means that e.g. Guid keys are not auto-generated because AutoGenerated is false.

But you're right, and we can have the attribute be bool, but have it read/write a backing field which is bool?. This way by default the backing field is null ("let the provider decide"), but if the user decides to set the value on the attribute, it's just a regular bool.