How Can I Effectively Bind a List to a View in ASP.NET MVC 4 During HttpPost?

Model Binding to a List in MVC 4

When attempting to bind an IList of items to a view in MVC 4, issues can arise during HttpPost. To address this challenge, consider the following pattern:

ViewModel:

Create a ViewModel that contains the IList of items:

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

View:

In the view, iterate over the IList and generate form inputs for each property:

@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)         
}

Action:

In the action method, handle the posted MyViewModel object:

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

Considerations:

• Only properties with corresponding inputs in the view will have values on HttpPost.
• MVC's model binding only works for consecutive IDs. If you conditionally hide items, data may not be bound correctly.
• To solve the issue of gaps in IDs, consider using this solution:

@for( int i = 0; i < Model.Persons.Count(); ++i)
{
    @Html.Hidden($"Persons[{i}].PersonId", Model.Persons[i].PersonId)
    @Html.Editor($"Persons[{i}].FirstName", Model.Persons[i].FirstName) 
    @Html.Editor($"Persons[{i}].LastName", Model.Persons[i].LastName)           
}

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