MVC client-side validation for multiple models

Question

I have three models: VehicleType , VehicleModel , and VehicleManufacturer .

Both VehicleType and VehicleManufacturer point to VehicleModel in the model, like so:

public class VehicleModel
{
    [Key]
    public int ModelId { get; set; }

    [Required(ErrorMessage = "Field is Required")]
    public int TypeId { get; set; }

    [Required(ErrorMessage = "Field is Required")]
    public int ManufacturerId { get; set; }
    public string ModelName { get; set; }


    public VehicleType VehicleType { get; set; }
    public VehicleManufacturer Manufacturer { get; set; }

}

From there, VehicleModel points to the InventoryModel:

 public class Inventory
{
    [Key]
    public int InventoryId { get; set; }
    public int Price { get; set; }
    public int Mileage { get; set; }
    public int Year { get; set; }


    public int ModelId { get; set; }
    public VehicleModel VehicleModel { get; set; }
}

My problem is when I try to get client-side validation working on all three dropdownlists ( VehicleType , VehicleManufacturer , VehicleModel ), it only works with VehicleModel .

What needs to be done to validate these two dropdownlists using these models?

Here is my controller (fyi):

 // GET: /Inventory/Create
    public ActionResult Create()
    {
        ViewBag.TypeId = new SelectList(db.Types, "TypeId", "TypeName"); //(Object List, Value Field (usually Id), Column)
        ViewBag.ModelId = new SelectList(db.Models, "ModelId", "ModelName"); //(Object List, Value Field (usually Id), Column)
        ViewBag.ManufacturerId = new SelectList(db.Manufacturers, "ManufacturerId", "ManufacturerName"); //(Object List, Value Field (usually Id), Column)

        return View();
    }

    // POST: /Inventory/Create
    // To protect from overposting attacks, please enable the specific properties you want to bind to, for 
    // more details see http://go.microsoft.com/fwlink/?LinkId=317598.
    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult Create(Inventory inventory, VehicleManufacturer VehicleManufacturer, VehicleType VehicleType)
    {
        if (ModelState.IsValid)
        {
            db.Inventorys.Add(inventory);
            db.SaveChanges();
            return RedirectToAction("Index");
        }

        ViewBag.TypeId = new SelectList(db.Types, "TypeId", "TypeName");
        ViewBag.ModelId = new SelectList(db.Models, "ModelId", "ModelName");
        ViewBag.ManufacturerId = new SelectList(db.Manufacturers, "ManufacturerId",     "ManufacturerName");

        return View(inventory);
    }

View:

 <div class="editor-label">
        @Html.LabelFor(model => model.VehicleModel.TypeId, "Some name for column")
    </div>
    <div class="editor-field">
        @Html.DropDownList("TypeId", String.Empty)

        @Html.ValidationMessageFor(model => model.VehicleModel.TypeId)
    </div>


    <div class="editor-label">
        @Html.LabelFor(model => model.ModelId, "Some name for column")
    </div>
    <div class="editor-field">
        @Html.DropDownList("ModelId", String.Empty)
        @Html.ValidationMessageFor(model => model.ModelId)
    </div>



    <div class="editor-label">
        @Html.LabelFor(model => model.VehicleModel.ManufacturerId, "Some name for column")
    </div>
    <div class="editor-field">
        @Html.DropDownList("ManufacturerId", String.Empty)
        @Html.ValidationMessageFor(model => model.VehicleModel.ManufacturerId)
    </div>

Please someone help. I've been on this for many, many hours!

Answer 1

There are actually two problems That I see above

1) That you're not mapping the DropDownList and the ValidationMessageFor to the same model attribute.

@Html.ValidationMessageFor(model => model.VehicleModel.ManufacturerId)

The above is binding it to VehicleModel_ManufacturerId where as:

@Html.DropDownList("ManufacturerId", String.Empty)

the above is mapping the DropDown to just ManufacturerId

You need to change one or the other to match each other.

2) In the above code, I don't see any Validation Attributes. did you forgot them when you copied the code over here?

Hope this helps, Let me know if you needed more details.