视图模型最佳实践中的ASP.NET MVC自定义验证

I am trying to use a combination of Domain Driven Design with Test Driven Development for this application I am building in ASP.NET MVC 3. My archictecture is set up with Repositories, Domain Models, View Models, Controllers and Views. All validation will be handled in the view model. I set up my view model to inherit from "IValidatableObject" so that my validation attributes and my custom validation that i set up in the "Validate" method are both executed when my controller method calls "ModelState.IsValid". The problem I am running into is accessing my repository in the Validate method of my view model. I need to access the repository to check for duplicate records in the database. It seems like the best idea would be to create a property of IRepository type and set that property by passing injecting my repository into the constructor of the view model. For example:I am trying to use a combination of Domain Driv