ASP.NET MVC Where to put custom validation attributes

Question

I've been fiddling with some ASP.NET MVC3 solution structures and I have settled on a design that is made up of the following projects:

MyApp.Web -  MVC3 Web Layer
MyApp.Data - Repositories and infrastructure for managing data
MyApp.Domain - POCO Entities
MyApp.Service - Service layer through with I manipulate the model
MyApp.Test - doh

Where would you put your custom validation attribute classes? As far as I'm concerned they should go in the Domain project because they are specific to the entity classes that live there, but then I would need to reference a number of dlls such as System.Web.MVC and I would have liked to have kept references in that project to a bare minimum. Thoughts?

Update:

I removed all attributes from my Domain project and created view models to wrap them in the Web project. Placed all my custom validation classes in a folder in the web project. Thanks guys

benwasd · Accepted Answer · 2011-06-08 19:14:00Z

4

I would create these attributes on the Web Project and append them to the viewmodel instead of the entity.

answered Jun 8, 2011 at 19:14

benwasd

1,35210 silver badges18 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

jgauffin · Accepted Answer · 2011-06-08 19:53:00Z

2

You do not need to reference the web dlls. Only System.ComponentModel.DataAnnotations

Put the validation attributes where they are use.d

Update

Why not? Almost every example I've seen uses POCOs in views. What's the alternative? Creating some kind of wrapper classes for my POCOs?

Because of:

Security

Let's say that you got a User POCO with an IsAdmin field. By using the POCO, the ModelBinder in MVC will set that property if it's POSTed by a "hacker" who therefore gain admin access.

Isolation

Using the POCO in your view makes your View indirectly dependent of your database. Sure, POCOs are supposed to remove that dependency. But in reality they seldom do.

Customization

You do seldom show all values in a view as they are stored in the db.

The code to adapt a model should not be in the view, but in the viewmodel. Use as little logic as possible in your views.

edited Jun 8, 2011 at 19:53

answered Jun 8, 2011 at 19:07

jgauffin

101k45 gold badges245 silver badges378 bronze badges

14 Comments

woggles Over a year ago

you need it for client side validation ie to implement IClientValidatable

jgauffin Over a year ago

Your POCOs shouldn't be used in your views.

woggles Over a year ago

Why not? Almost every example I've seen uses POCOs in views. What's the alternative? Creating some kind of wrapper classes for my POCOs?

Darin Dimitrov Over a year ago

@woggles, then those are bad examples that you have seen :-)

jgauffin Over a year ago

Because of Security, Isolation and Customization. a) Let's say that you got a User POCO with an IsAdmin field. By using the POCO, the ModelBinder in MVC will set that property if it's posted by a "hacker". b) Using the POCO in your view makes your View indirectly dependent of your database. c) Your ViewModel should contain logic to adapt it, not your view (remove all code from views and add it to the viewmodels instead).

|

Justin Soliz · Accepted Answer · 2011-06-08 19:42:40Z

0

I would have DataAnnotation Attributes in your Web Project, preferably in a Common.Attributes folder. I think what jgauffin was getting at (and I'd agree) is that your CustomAttributes should really be decorating ViewModels vs Entities in your Domain project.

answered Jun 8, 2011 at 19:42

Justin Soliz

2,8014 gold badges26 silver badges33 bronze badges

Comments

Konstantin · Accepted Answer · 2011-06-15 07:50:38Z

0

I would have followed your original intent of adding the attributes to the Domain objects

answered Jun 15, 2011 at 7:50

Konstantin

3,7162 gold badges35 silver badges46 bronze badges

Collectives™ on Stack Overflow

ASP.NET MVC Where to put custom validation attributes

4 Answers 4

Comments

Update

14 Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

Update

14 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related