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?

This is normal behavior. The model binder uses the name property of the input elements from the rendered html. Using a for loop with an indexer is the only way to have unique names that the model binder can associate to the model — Forty-Two
– Forty-Two, Commented Jan 4, 2013 at 22:00

Rafay · Accepted Answer · 2013-01-04 22:29:32Z

62

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

edited Jan 4, 2013 at 22:29

answered Jan 4, 2013 at 22:01

Rafay

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1 Comment

Eric Over a year ago

This will not work on an Generic.IEnumerable collection so you will need to change your collection to some form of an indexable collection.

ICode · Accepted Answer · 2014-03-27 12:29:46Z

0

All you missed was placing var instead of the Model itself(People) like below

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

answered Mar 27, 2014 at 12:29

ICode

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3 Comments

Eric Over a year ago

Wont work for post requests as the json deserializer will not be able to match these properties to the fields.

Muhammad Ashikuzzaman Over a year ago

It is working but every input form has same name and same value.

Muhammad Ashikuzzaman Over a year ago

@nam means in razor view the loop is working and generating it's corresponding html elements. But every "name" input field id and name is "name" and every "age" input field id and name is "age"

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