I am currently working on an ASP.NET MVC2 project. This is the first time I am working on a real MVC web application. The ASP.NET MVC website really helped me to get started really fast, but I still have some obscure knowledge concerning datamodel validation.
My problem is that I do not really know where to manage my filled datamodel when it comes to complex validation rules. For example, validating a string field with a Regex is quite easy and I know that I just have to decorate my field with a specific attribute, so data management rules are implemented in the model. But if I have multiple fields that I need to validate which each other, for example multiple datetime that need to be correctly set following a specific time rule, where do I need to validate them? I know that I could create my own validation attributes, but sometimes validation ask a specific validation path which is to complex to be validated using attributes.
This first question also leads me to a related question which is, is it right to validate a model in the controller? Because for the moment that is the only way I found for complex validation. But I find this a bit dirty and I feel it does not really fit a the controller role and much harder to test (multiple code path).
NB: I got some pretty good solutions here but I am waiting for other ideas and some "best practice" solution".
Creating Database Mocks in ASP.NET MVC using Data from Existing Database