How to edit nested collections in MVC5? - entity-framework

Question

I have a EF-model which contains a "key" and a "value". The value-table contains a FK to the key. In the EF-model it looks like this:
public partial class dict_key
{
public dict_key()
{
this.dict_value = new HashSet<dict_value>();
}
public int id { get; set; }
public string name { get; set; }
...
public virtual ICollection<dict_value> dict_value { get; set; } //dict_value contains a string "value"
}
My controller is passing the information for editing like this:
// GET: Keys/Texts/5
[Authorize]
public async Task<ActionResult> Texts(int? id)
{
var key = await db.dict_key
.Include(x => x.dict_value)
.Where(x => x.id.Equals(id.Value))
.FirstOrDefaultAsync();
return View(key);
// Debugging 'key' shows that dict_value has 3 correct values.
}
This gets passed to my View which shows the dict_value's correct:
#model Dict.Models.dict_key
#using (Html.BeginForm())
{
<div>Key: #Model.name </div>
<table class="table">
<tr>
<th>Language</th>
<th>Text</th>
</tr>
#for (var i = 0; i < Model.dict_value.Count(); i++)
{
<tr>
<td> #Model.dict_value.ElementAt(i).dict_lang.name_en </td>
<td> #Html.EditorFor(x => x.dict_value.ElementAt(i).value) </td>
</tr>
}
<div class="form-group">
<input type="submit" value="Save" />
</div>
</table>
}
When submitting my changes back to the controller...
[HttpPost]
public async Task<ActionResult> Texts(dict_key dict_key)
{
if (ModelState.IsValid)
{
//Also tried: db.Entry(dict_key).State = EntityState.Modified;
db.Entry(dict_key.dict_value).State = EntityState.Modified;
await db.SaveChangesAsync();
return RedirectToAction("Texts");
}
return View(dict_key);
}
..then my "dict_key" is totally different from the object I passed to my edit-view. The passed object contained the collection of dict_value's and the "returned" and edited object returns with the proper key object, but with an empty dict_value collection.
I try to avoid using a userdefined model or the viewbag to do all of that stuff manually. What is the best practise solution for this?

Answer 1

Collection.ElementAt doesn't generate a proper field name in Razor. You need a List. Here you should use a view model instead of your entity directly and simply make your dict_value collection a List<dict_value> there.
Alternatively, you can create an editor template for dict_value and then in your view just do:
#Html.EditorFor(m => m.dict_value)
Where dict_value there is your entire collection. Razor will render an instance of the editor template for each member of the collection and properly index everything.