Please add `Attributes` property to `ModelMetadata`.

[alireza-salemian]

In many scenarios we use reflection and in Mvc.NetCore base class ModelMetadata is a good class for that models, but property Attributes is not exist in this type and its necessary cast to DefaultModelMetadata to access it.
Please move this property from DefaultModelMetadata to ModelMetadata.
ex:
var property = modelMetadata.Properties .OfType<DefaultModelMetadata>() .FirstOrDefault(p => p.Attributes.PropertyAttributes.OfType<SelectOptionsValueMapAttribute>().Any() || p.Name == "Id");

[mkArtakMSFT]

Thanks for contacting us, @alireza-salemian.
@dougbu thoughts?

[dougbu]

@mkArtakMSFT DefaultModelMetadata.Attributes should have been internal because the attribute collection is not intended for use after instances are created. We shouldn't make that collection public.

@alireza-salemian if SelectOptionsValueMapAttribute is meaningful in your application, handle it in a registered IMetadataDetailsProvider implementation and add the information you need to context.DisplayMetadata.AdditionalValues. Then, use the newly-exposed data wherever it's needed.

[alireza-salemian]

@dougbu We use knockout in our projects. generate client js model from original c# model using Reflection and Custom Attributes. every Validation attribute exposed to client model and many other attribute. if use IMetadataDetailsProvider then duplicate memory required for cache metadata and additional processing is done.

[mkArtakMSFT]

Hi @alireza-salemian.
we have no plans to expose the DefaultModelMetadata.Attributes property. The suggested behavior is our recommended solution.