I was one of the developers that ported the System.ComponentModel.DataAnnotations assembly to Silverlight. Every once in awhile, someone asks me if the Silverlight version of the assembly is a subset of what is in .NET. The answer is Yes, but there are some caveats, and I’m honestly tired of regurgitating the detailed answer. With this blog post in place, I can now simply point people to a URL for the answer. This is what we call DRY.
I’m sure that it goes without saying that the implementation details of the two assemblies differ. In the .NET version, we have TypeDescriptor at our disposal, and it’s used to gather metadata about types and members. In Silverlight, TypeDescriptor doesn’t exist, so raw Reflection is used in its place. Moreover, .NET offers the MetadataTypeAttribute to allow metadata to be loaded from another type--Silverlight doesn’t support that either, so again the implementations differ rather significantly. There are other reasons for implementation differences too, but it suffices to say that underneath the public API, the differences are manifold.
Public API Differences:
| Type / Member | .NET | Silverlight | Notes |
| AssociatedMetadataTypeTypeDescriptionProvider | Yes | No | |
| AssociationAttribute | Yes | Yes | |
| AssociationAttribute.TypeId | Yes | No | Due to Attribute difference |
| ConcurrencyCheckAttribute | Yes | Yes | |
| CustomValidationAttribute | Yes | Yes | |
| CustomValidationAttribute.TypeId | Yes | No | Due to Attribute difference |
| DataType | Yes | Yes | |
| DataTypeAttribute | Yes | Yes | |
| DataTypeAttribute.IsValid(Object) | Yes | No | Internal in Silverlight |
| DisplayAttribute | Yes | Yes | |
| DisplayColumnAttribute | Yes | Yes | |
| DisplayColumnAttribute.HtmlEncode | Yes | No | |
| EditableAttribute | Yes | Yes | |
| EnumDataTypeAttribute | Yes | Yes | |
| EnumDataTypeAttribute.IsValid(Object) | Yes | No | Internal in Silverlight |
| FilterUIHintAttribute | Yes | Yes | |
| FilterUIHintAttribute.TypeId | Yes | No | Due to Attribute difference |
| IValidatableObject | Yes | No | |
| KeyAttribute | Yes | Yes | |
| MetadataTypeAttribute | Yes | No | |
| RangeAttribute | Yes | Yes | |
| RangeAttribute.IsValid(Object) | Yes | No | Internal in Silverlight |
| RegularExpressionAttribute | Yes | Yes | |
| RegularExpressionAttribute.IsValid(Object) | Yes | No | Internal in Silverlight |
| RequiredAttribute | Yes | Yes | |
| RequiredAttribute.IsValid(Object) | Yes | No | Internal in Silverlight |
| ScaffoldColumnAttribute | Yes | No | |
| ScaffoldTableAttribute | Yes | No | |
| StringLengthAttribute | Yes | Yes | |
| StringLengthAttribute.IsValid(Object) | Yes | No | Internal in Silverlight |
| TimestampAttribute | Yes | Yes | |
| UIHintAttribute | Yes | Yes | |
| UIHintAttribute.TypeId | Yes | No | Due to Attribute difference |
| ValidationAttribute | Yes | Yes | |
| ValidationAttribute.IsValid(Object) | Yes | No | Internal in Silverlight |
| ValidationAttribute.Validate(Object, String) | Yes | No | |
| ValidationContext | Yes | Yes | |
| ValidationContext.ServiceContainer | Yes | No | |
| ValidationException | Yes | Yes | |
| ValidationException.ctor(SerializationInfo, StreamingContext) | Yes | No | |
| ValidationResult | Yes | Yes | Sealed in Silverlight, not in .NET |
| ValidationResult.ToString | Yes | No | Overridden in Silverlight, not in .NET |
| Validator | Yes | Yes |