Checking custom attribute parameters at design/build time

Question

I have a CustomAuthorize attribute that checks to see if a user has access to functionality (a user or role can be associated with items from a hierarchical set of functions).

For a given action method...

[CustomAuthorize("Security.Admin.ManageWidgets.Update")]

This works but I'm concerned that changes to the Security object could cause problems that won't be detected until run-time. I realize that I can write unit tests to mitigate this risk but I would like to know if it is possible to check the attribute parameter at compile time. I also like having Intellisense help me type this expression.

Ideally, I could pass a lambda expression.

[CustomAuthorize(i => i.Admin.ManageWidgets.Update)]

Unfortunately this is not currently possible (additional info from Microsoft).

I also tried encapsulating the expression hoping it would be evaluated and then passed to the attribute as a string, but this also failed to compile with the same error (Expression cannot contain anonymous methods or lambda expressions).

[CustomAuthorize(LambdaToString(i => i.Admin.ManageWidgets.Update))]

How can I add some design-time / build-time support for my custom attribute parameters?

Answer 1

A Static class with constants.

public static class Rights
{
    public const string UpdateWidgets = "UpdateWidgets";
}

Also include unittests for the methods which are decorated with them and you'll be pretty good.

[CustomAuthorize(Rights.UpdateWidgets)]

Answer 2

You can use T4 templates to create custom classes with string properties, ending up with code similar to BennyM's, but generated automatically.