Conditional validation on model in MVC

by

If you’re on MVC3/.NET4, you can use IValidatableObject which exists specifically for such purposes.

Quoting ScottGu,

…The IValidatableObject interface enables you to perform model-level
validation, and enables you to provide validation error messages
specific to the state of the overall model….

You model would look like

public class MyViewModel : IValidatableObject
{
    public long? Id { get; set; }
    public decimal? ProposedCost { get; set; }

    public IEnumerable<ValidationResult> Validate(ValidationContext validationContext) 
    { 
        if (Id != null && ProposedCost == 0) {
            yield return new ValidationResult("ProposedCost must be provided.");
        }
    }
}

and then in the controller,

[HttpPost]
public ActionResult Submit(MyViewModel model)
{
    if (!ModelState.IsValid) {
        //failed - report an error, redirect to action etc
    }
    //succeeded - save to database etc
}

Otherwise, the most clean solution would be to use view models – UpdateViewModel where the property is required, and CreateViewModel where it’s not required.

More Related Contents:

  1. How to get ELMAH to work with ASP.NET MVC [HandleError] attribute?
  2. Polymorphic model binding
  3. MVC DateTime binding with incorrect date format
  4. TempData keep() vs peek()
  5. Real example of TryUpdateModel, ASP .NET MVC 3
  6. allowDefinition=’MachineToApplication’ error when publishing from VS2010 (but only after a previous build)
  7. Razor-based view doesn’t see referenced assemblies
  8. Why is my CSS bundling not working with a bin deployed MVC4 app?
  9. ASP.NET: This method cannot be called during the application’s pre-start initialization stage
  10. Could not load file or assembly HRESULT: 0x80131515 (When adding controller to MVC project that has assembly references on network drive)
  11. MVC Routing Parameter Precedence
  12. String URL to RouteValueDictionary
  13. How can I combine two fields in a SelectList text description?
  14. In C#, how can I know the file type from a byte[]?
  15. How to display an image from a path in asp.net MVC 4 and Razor view?
  16. MVC 5 Seed Users and Roles
  17. Redirecting to specified controller and action in asp.net mvc action filter
  18. ASP.NET MVC – How to access Session data in places other than Controller and Views
  19. 500 Internal Server Error in ASP.NET MVC
  20. MVC post a list of complex objects
  21. Set disable attribute based on a condition for Html.TextBoxFor
  22. Why is DisplayFormat DataFormatString not working?
  23. Custom Authorize Attribute
  24. Overriding controller AuthorizeAttribute for just one action
  25. MVC4 enum and radio button list
  26. How can I use Html.Action?
  27. ASP.NET Web API, unexpected end of MIME multi-part stream when uploading from Flex FileReference
  28. MVC role-based routing
  29. deploying AntiforgeryToken Error
  30. How to create custom scaffold templates in ASP.NET MVC5?

Leave a Comment