Model binding a collection property with a partial view

Question

Suppose I have a model like this:

public class Foo {
    public List<Bar> Bars { get; set; }
    public string Comment { get; set; }
}

public class Bar {
    public int Baz { get; set; }
}

And I want a view of Foo that lets users edit Bar items. But with a catch: I want the Bar editing to be handled by a partial view.

@model Web.ViewModels.Foo

@using(Html.BeginForm()) {
    @Html.Partial("_EditBars", Model.Bars)
    @Html.TextAreaFor(m => m.Comment)
    ...
}

The _EditBars partial view looks something like:

@model List<Web.ViewModels.Bar>

@for (int i = 0; i < Model.Count; i++) {
    @Html.EditorFor(m => Model[i].Baz)
}

I want this to model bind to my action, which looks something like:

[HttpPost]
public ActionResult Edit(Foo foo) {
    // Do stuff
}

Unfortunately, this is the data that I'm posting, which doesn't model bind the Bars property:

[1].Baz=10&[0].Baz=5&Comment=bla

It makes sense that this doesn't work, because it's missing the Bars prefix. If I understand correctly, I need it to be this:

Bars[1].Baz=10&Bars[0].Baz=5&Comment=bla

So, I tried this approach:

@Html.Partial(
    "_EditBars",
    Model.Bars,
    new ViewDataDictionary(ViewData)
    {
        TemplateInfo = new TemplateInfo
        {
            HtmlFieldPrefix = "Bars"
        }
    }) 

But that's not working either. With that, I'm getting:

Bars.[1].Baz=10&Bars.[0].Baz=5&Comment=bla

I assume that that isn't working because of the extra period (Bars.[1] vs. Bars[1]). Is there anything I can do to get the result that I desire?

Note: This is a major oversimplification of my actual situation. I recognize that with something this simple, the best approach would probably be to make an EditorTemplate for Bar and loop through using EditorFor in my view. If possible, I'd like to avoid this solution.

Answer 1

As you do not want to use an EditorTemplate for Bar, a solution of your scenario could be:

Change the @model type of the '_EditBars' partial view to Foo and view should be like:

@model Foo

@if (Model.Bars != null)
{
    for (int i = 0; i < Model.Bars.Count; i++)
     {
         @Html.EditorFor(m => Model.Bars[i].Baz)
     }
}

(It would be better to change the partial view's name to '_EditFooBars')

Hope this helps.