How Can I Efficiently Bind Lists of Items to Views in MVC 4?

Custom Model Binding for Lists in MVC 4

Binding a list of items (IList) to a view in MVC has been a common challenge for developers. While older solutions exist, MVC 4 introduces enhancements that simplify the process.

For scenarios where each item in the list requires its own form for data entry, consider structuring your ViewModel as follows:

public class MyViewModel
{
   public List<Person> Persons{get;set;}
}

In the View, within the BeginForm:

@model MyViewModel


@for( int i = 0; i < Model.Persons.Count(); ++i)
{
    @Html.HiddenFor(m => m.Persons[i].PersonId)
    @Html.EditorFor(m => m.Persons[i].FirstName) 
    @Html.EditorFor(m => m.Persons[i].LastName)         
}

The HttpPost action would receive the updated View Model:

[HttpPost]public ViewResult(MyViewModel vm)
{
...
}

Note that on postback, only properties with corresponding inputs in the form will have values. This is because MVC's model binding looks for consecutive IDs and stops binding after encountering a gap. Therefore, it's important to ensure that all items in the list have valid IDs and no gaps in the form.

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