Question

Here is my problem. I have a list of models that are displayed to the user. On the left is a checkbox for each model to indicate that the user wants to choose this model (in this case, we’re building products a user can add to their shopping cart). The model has no concept of being chosen…it strictly has information about the product in question.

I’ve talked with a few other developers after having gone through and the best I could come up with is getting the formcollection and string parsing the key values to determine whether the checkbox is checked or not. This doesn’t seem ideal. I was thinking there would be something more strongly bound, but I can’t figure out a way to do it.

I tried creating another model that had a boolean property to represent being checked and a property of the model and passing a list of that model type to the view and creating a ActionResult on the controller that accepts a list of the new model / checked property, but it comes back null. Am I just thinking too much like web forms and should just continue on with parsing checkbox values?

Here’s what I’ve done for wrapping the models inside a collection:

public class SelectableCollection[T] : IList[T] {} 
public class SelectableTrack{ 
  public bool IsChecked{get;set;} 
  public bool CurrentTrack{get;set;} 
} 

For the view, I inherit from

ViewPage[SelectableCollection[SelectableTrack]] 

For the controller, I have this as the ActionResult:

    [HttpPost] 
    public ActionResult SelectTracks(SelectableCollection sc) { 

       return new EmptyResult(); 
    } 

But when I break inside the ActionResult, the collection is null. Any reason why it isn't coming through?

Answer 1

You don’t want to bind the entire page to the collection.

• Create a class called MyViewModel (or whatever makes sense, use the name of the View in the name.) Make that class the basis of your strongly-typed View.
• Add the SelectableCollection<T> as a property of the ViewModel (call it SelectedProducts or whatever,) and populate it in the Controller.
• Bind the checkboxes to the SelectedProducts property.

Also, are you using a custom CheckBoxList helper? There is not one out-of-the-box with ASP.NET MVC. Use this post to build your checkboxes:

How to handle checkboxes in ASP.NET MVC forms?