DynamoDB AOT fails for type and collection properties

[dscpinheiro]

@normj
I've tested AOT integration with 4.0.0-preview.6.
There were no AOT warnings, however apparently, it doesn't support type properties and collection properties.

1. Nested Types:

var nestedTypeId = Random.Shared.Next().ToString();
await context.SaveAsync(new TypeWithNestedTypeProperty
{
    Id = nestedTypeId,
    Name = "Test",
    SubType = new SubType() { SubName = "Subname" }
});
Console.WriteLine("Item saved.");

var nestedItem = await context.LoadAsync<TypeWithNestedTypeProperty>(nestedTypeId);
Console.WriteLine($"Item loaded: {nestedItem}");
Console.WriteLine($"SubType.SubName: {nestedItem.SubType.SubName}");

[DynamoDBTable("TestTable")]
class TypeWithNestedTypeProperty
{
    [DynamoDBHashKey]
    public string Id { get; set; }
    public string Name { get; set; }
    public SubType SubType { get; set; }
}

class SubType
{
    public string SubName { get; set; }
}

Result:

Unhandled Exception: System.InvalidOperationException: Type SubType is unsupported, it cannot be instantiated
   at Amazon.DynamoDBv2.DataModel.StorageConfig..ctor(Type) + 0x14f
   at Amazon.DynamoDBv2.DataModel.ItemStorageConfig..ctor(Type) + 0x12
   at Amazon.DynamoDBv2.DataModel.ItemStorageConfigCache.CreateStorageConfig(Type, String, DynamoDBFlatConfig) + 0x43
   at Amazon.DynamoDBv2.DataModel.ItemStorageConfigCache.GetConfig(Type, DynamoDBFlatConfig, Boolean) + 0x144
   at Amazon.DynamoDBv2.DataModel.DynamoDBContext.SerializeToDocument(Object, Type, DynamoDBFlatConfig) + 0x2c
   at Amazon.DynamoDBv2.DataModel.DynamoDBContext.ToDynamoDBEntry(SimplePropertyStorage, Object, DynamoDBFlatConfig, Boolean) + 0x125
   at Amazon.DynamoDBv2.DataModel.DynamoDBContext.PopulateItemStorage(Object, ItemStorage, DynamoDBFlatConfig, Boolean, Boolean) + 0xe6
   at Amazon.DynamoDBv2.DataModel.DynamoDBContext.ObjectToItemStorage(Object, Type, Boolean, DynamoDBFlatConfig) + 0x7e
   at Amazon.DynamoDBv2.DataModel.DynamoDBContext.<SaveHelperAsync>d__48.MoveNext() + 0x5d

2. Collection property:

var listTypeId = Random.Shared.Next().ToString();
await context.SaveAsync(new TypeWithCollectionProperty
{
    Id = listTypeId,
    Name = "Test",
    Items = new List<string> { "1", "2", "3" }
});
Console.WriteLine("Item saved.");

var collectionItem = await context.LoadAsync<TypeWithCollectionProperty>(listTypeId);
Console.WriteLine($"Item loaded: {collectionItem}");
Console.WriteLine($"Items: {string.Join(",", collectionItem.Items)}");

Result:

Unhandled Exception: System.InvalidOperationException: Cannot instantiate type System.Collections.Generic.List`1[[System.String, System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]]
   at Amazon.DynamoDBv2.DataModel.Utils.InstantiateHelper(Type, Type[][], Object[]) + 0x119
   at Amazon.DynamoDBv2.DataModel.Utils.ItemsToIList(Type, IEnumerable`1, Object&) + 0x42
   at Amazon.DynamoDBv2.Converter.TryFromEntry(DynamoDBEntry, Type, Object&) + 0x79
   at Amazon.DynamoDBv2.Converter.FromEntry(DynamoDBEntry, Type) + 0x39
   at Amazon.DynamoDBv2.DataModel.DynamoDBContext.FromDynamoDBEntry(SimplePropertyStorage, DynamoDBEntry, DynamoDBFlatConfig) + 0x7f
   at Amazon.DynamoDBv2.DataModel.DynamoDBContext.PopulateInstance(ItemStorage, Object, DynamoDBFlatConfig) + 0xc4
   at Amazon.DynamoDBv2.DataModel.DynamoDBContext.DocumentToObject(Type, ItemStorage, DynamoDBFlatConfig) + 0x47
   at Amazon.DynamoDBv2.DataModel.DynamoDBContext.DocumentToObject[T](ItemStorage, DynamoDBFlatConfig) + 0x32
   at Amazon.DynamoDBv2.DataModel.DynamoDBContext.<LoadHelperAsync>d__57`1.MoveNext() + 0x1c4

Attaching sample project:
DdbAORRepro.zip

Originally posted by @Dreamescaper in #3475

[Dreamescaper]

Personally, I don't think it is possible to fully fix without a Source Generator.
(It is possible to workaround for some specific types - like specifically for List<T>. But not for any arbitrary type.)

But it probably should be documented somehow.

[normj]

Good catch. You are probably right that a source generator would be the ideal solution but not something we have bandwidth for, at least in the near future. You can work around the issue by adding the DynamicDependency attribute for the nested type. I think what I will do in the short time is catch the System.InvalidOperationException: Type <type> is unsupported, it cannot be instantiated and rethrow with a message that hints at using DynamicDependency when running in Native AOT mode. It will also call this limitation in our documentation as we get that ready for V4. I did update the V4 tracker issue about this limitation. #3362

[DynamoDBTable("TestTable")]
class TypeWithNestedTypeProperty
{
    [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(SubType))]
    public TypeWithNestedTypeProperty()
    {

    }

    [DynamoDBHashKey]
    public string Id { get; set; }
    public string Name { get; set; }

    public SubType SubType { get; set; }
}

class SubType
{
    public string SubName { get; set; }
}

[Dreamescaper]

Regarding specifically collection properties. DynamoDBContext supports very limited set of collection types - T[], List<T>, HashSet<T>.
Therefore, it is possible to create those specific types mostly without reflection, and to be AOT compatible.
(see https://github.com/aws/aws-sdk-net/pull/3300/files#diff-e9d2d59bba99ce62d79158551bd80d3d71d18a3ba7f60059bdd915fdae5abbbf )

Not sure if anything could be done for nested types...

[MichalStrehovsky]

Why is there no AOT/trim warning generated? Does the library have an invalid warning suppression or did the tooling miss something?

[Dreamescaper]

@MichalStrehovsky
Probably due to warning suppressions.

Anyway, I've created a discussion at dotnet/runtime, which would potentially allow supporting nested types without a source generator.
Maybe it gets some traction.
dotnet/runtime#112356

[normj]

@MichalStrehovsky When the type the user wants to save into DynamoDB is passed into our library I'm using the attribute DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.All) knowing the SDK will do need to access all of the properties and fields and at least the 0 parameter constructor. I had assume by using DynamicallyAccessedMemberTypes.All that should include all the metadata on the types referenced by parent type. I figured DynamicallyAccessedMemberTypes.All was basically saying I need this whole type to not be trimmed because in our case we need to do all the reflection on the type. Am I misunderstanding the meaning of DynamicallyAccessedMemberTypes.All?