ASP.NET MVC 4 - for loop posts model collection properties but foreach does not

Question

Say I have the following models:

public class Person
{
    public string Name { get; set; }
    public int Age { get; set; }
}

public class Town
{
    public string Name { get; set; }
    public IEnumerable<Person> People { get; set; }
}

Then, in my Razor view, I have this:

@model Town
@using(Html.BeginForm())
{
    <table>
        @foreach(var person in Model.People)
        {
            <tr>
                <td>@Html.TextBoxFor(m => person.Name)</td>
                <td>@Html.TextBoxFor(m => person.Age)</td>
            </tr>
        }
    <table>
    <input type="submit" />
}

Then, I have an action for the POST, something like this:

[HttpPost]
public ActionResult Index(Town theTown)
{
    //....
}

When I post, the IEnumerable<Person> does not come across. If I look at it in Fiddler, the collection only posts once, and doesn't enumerate the collection, so I get:

People.Name = "whatever"
People.Age = 99

However, if I change People to an IList and use a for loop instead of a foreach...

@for(var i = 0;i < Model.People.Count;i++)
{
    <tr>
        <td>@Html.TextBoxFor(m => Model.People[i].Name)</td>
        <td>@Html.TextBoxFor(m => Model.People[i].Age)</td>
    </tr>
}

It works. Am I doing something wrong? What am I missing?

Answer 1

the problem is not with the IEnumerable or the IList it the way you are rendering the collection in your view.

@for(var i = 0;i < Model.People.Count;i++)
{
    <tr>
        <td>@Html.TextBoxFor(m => Model.People[i].Name)</td>
        <td>@Html.TextBoxFor(m => Model.People[i].Age)</td>
    </tr>
}

Observe that with each list item you are appending a continuous index which enables the model binder to do its magic

A good read