ASP.NET MVC Model Binding to a Single Property in a List of Complex Objects

Question

.NET 4.5
ASPNET.MVC 5

On the web page of interest, within a list of complex objects, I am trying to edit only one property for each complex object.

Let's say that my complex class looks like this:

public class MyClass
{
   [Required]
   public int MyClassID {get; set;}     // Primary Key
   [Required]
   public int Prop1 { get; set; }       // an integer property
   [Required]
   public string Prop2 { get; set; }    // a string property
   [Required]
   public EnumType Prop3 { get; set; }  // an enum property that's being changed
}

In my form, I am trying to edit a list of MyClass objects in which only Prop3 is changed.

These are my Get and Post methods in my Controller:

[HttpGet]
public ActionResult ChangeJustProp3InList()
{
   .
   . /* some validation stuff */
   .
   var myList = new List<MyClass>
       {
          /*... some MyClass objects ...*/ 
       };
   return View(myList);
}

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult ChangeJustProp3InList(List<MyClass> myList)
{
   .
   . /* some stuff I think is unnecessary for this question */
   .
}

This is my View:

@model IList<MyClass>

   .
   . /* some html */
   .

@using (Html.BeginForm("ChangeJustProp3InList", "MyController", FormMethod.Post))
{
   @Html.AntiForgeryToken()
   @Html.ValidationSummary()

   for (int i = 0; i < Model.Count; i++)
   {
      Html.HiddenFor(model => Model[i].MyClassID);
      Html.HiddenFor(model => Model[i].Prop1);
      Html.HiddenFor(model => Model[i].Prop2);

      var uniqueID = "MyClass" + Model[i].MyClassID; <!-- html needs unique "id" attribute for each MyClass object -->
      Html.RadioButtonFor(model => Model[i].Prop3, EnumType.Choice1, new { id = uniqueID });
      Html.RadioButtonFor(model => Model[i].Prop3, EnumType.Choice2, new { id = uniqueID });
      Html.RadioButtonFor(model => Model[i].Prop3, EnumType.Choice3, new { id = uniqueID });
   }
   <a><input type="submit" value="Submit" class="btn btn-default center-block" /></a>
}

(There may be some syntax errors above relating to going between c# and html markup with razor. Please ignore those, as I tried to eliminate as much unnecessary code as possible.)

Note that I am the Prop3 property is an enum being updated with a radio button control.

So, presently, I am able to post any changes to the Prop3property for each MyClass object. However, every other property (Prop1, Prop2, and even MyClassID) is reset to default values (null, 0, etc.). I would like retain the values that were there originally.

I was thinking of Binding using the BindAttribute as follows...

public ActionResult ChangeJustProp3InList([Bind(Include = "<only Prop3>"] List<MyClass> myList)

But I couldn't find anything that binds a single property within a list of complex types. Any ideas?

My question is somewhat related to the one posed here: ASP.Net MVC - How to include / exclude binding of certain child collection / enumerable properties?

Unclear what your wanting to do. If you exclude the other properties, then `ModelState` will be invalid because of the `[Required]` attributes. And what is the point of including hidden inputs for the other properties is you don't want them to be bound? Either use a view model (without the attributes) and in the POST method, get the original list and update it based on the posted values for `Prop3` (and remove the hidden inputs) or bind the whole model. — , Dec 02 '15 at 06:26

ASP.NET MVC Model Binding to a Single Property in a List of Complex Objects

0 Answers0