Question

I would like to “turn off” the Required field validation on a certain property of the parent model (VehicleManufacturer), when saving a child model (VehicleModel), i.e.:

public class VehicleManufacturer
{
    public virtual Guid Id { get; set; }

    [Required]
    [StringLength(50, MinimumLength = 1)]
    public virtual string Name { get; set; }
}

public class VehicleModel
{
    public virtual Guid Id { get; set; }

    [Required]
    [StringLength(50, MinimumLength = 1)]
    public virtual string Name { get; set; }

    public virtual VehicleManufacturer Manufacturer { get; set; }
}

So, when I’m saving a new model, all I care about is it’s Name and ManufacturerID, which would be selected from a drop-down list, however, because the ManufacturerName is marked [Required] in its entity, it invalidates my ModelState when saving a new VehicleModel, because ManufacturerName is null 🙁

I would like to know what is the best approach to this and how to do it.
I can think of a few solutions but none seem to be the right way:

• Set a “default” ManufacturerName value before ModelState check, i.e.
  “-” just to satisfy the DataAnnotation
• Populate both ManufacturerName
  and ManufacturerId in my VehicleModelView – not good if your parent
  model has a bunch of required field you don’t really need to use in a
  child model
• Turn off [Required] validation for child model (not sure
  how?)

what do you think?

Answer 1

A possible solution is to add the foreign key column to the VehicleManufacturer (VehicleManufacturerId) to the VehicleModel and use that column in your view.