Per-row inline editor with individual Submit buttons - asp.net-mvc

Question

I have a scenario where I would like to have a list of editable items with per-item submit button, i.e. it should be allowed to submit only one item at a time.
I tried different approaches and the best answer I could find was this one: How to use multiple form elements in ASP.NET MVC, but the problem is that it assumes a single form and therefore a single Submit button.
So, here is what I tried so far. The Model:
namespace TestWebApplication4.Models
{
public class Entity
{
public int Id { get; set; }
[Required]
public string Name { get; set; }
}
public class TestModel
{
public IEnumerable<Entity> Entities { get; set; }
}
}
so I have a collection of Entity objects, which I want to display collectively, and edit and submit individually. The way I'm trying to do it is to have multiple forms on one View:
#using TestWebApplication4.Models
#model TestWebApplication4.Models.TestModel
#{
int i = 0;
foreach (Entity entity in Model.Entities)
{
i++;
<div>
#using (Html.BeginForm("Index"))
{
#Html.HiddenFor(model => entity.Id)
#Html.TextAreaFor(model => entity.Name, new {id = "entity_Name" + i})
#Html.ValidationMessageFor(model => entity.Name)
<button type="submit">Submit</button>
}
</div>
}
}
and the Controller:
namespace TestWebApplication4.Controllers
{
public class TestController : Controller
{
public ActionResult Index()
{
var model = BuildModel();
return View(model);
}
[HttpPost]
public ActionResult Index(Entity entity)
{
if (!ModelState.IsValid)
{
var model = BuildModel(entity);
return View(model);
}
return RedirectToAction("Index");
}
private static TestModel BuildModel(Entity entity = null)
{
var entities = new List<Entity>
{
new Entity {Id = 11, Name = "Product A"},
new Entity {Id = 12, Name = "Product B"},
new Entity {Id = 13, Name = "Product C"},
};
if (entity != null)
entities[entities.IndexOf(entities.Single(e => e.Id == entity.Id))] = entity;
return new TestModel {Entities = entities};
}
}
}
As you can see, I'm trying to receive individual Entity object in [HttpPost] Index action, and if it is invalid (Name value is not provided) to re-build the entire list and replace specific Entity with the invalid one (all of this happens in BuildModel method), to display the validation message. This however does not work properly, as the resulting view contains 3 entries, all with the same invalid Entity, i.e. I get three empty TextAreas and three "The Name field is required." validation messages.
Can anyone help me figure this out? I assume I'm doing something against the conventions and that it is probably completely wrong approach to this problem, however I could not find a solution anywhere myself, so any directions would be appreciated. Thanks in advance.