Associate attribute with code generated property in .net

Question

I wish to set an attribute on a public property in .NET, however I do not have access to the explicit property itself, as this has been code generated in another file.

Answer 1

This is a known nuisance; you simply can't add metadata to the generated members.

There are 6 options here (in order of increasing effort):

• if you own the attribute, make it possible to declare it against the class, for example: [ValidateNonEmpty("Name", "Name is required", ExecutionOrder = 1)] - then add multiple attributes to the partial class definition
• use a virtual / interface / etc method to query this, rather than via attributes
• sublass the generated type; override or re-declare the member, adding the metadata (really messy)
• use a custom TypeDescriptionProvider to provide dynamic metadata (lots and lots of work) - assuming that the consumer respects TypeDescriptor; most binding-related consumers do, but for example, Expression (used by many LINQ providers) doesn't
• change the code-generator / write your own
• try to extend something like PostSharp to do the work (I haven't found a way to do this, but I've love to hear if you find a way!)

I usually have success with the first option, unless it is a system-defined attribute ([DisplayName], etc). If [ValidateNonEmpty] is defined by dynamic data, then you might not be able to do this.