ASP.NET MVC, passing Model from View to Controller

Question

I'm having trouble with ASP.NET MVC and passing data from View to Controller. I have a model like this:

 public class InputModel {
   public List<Process> axProc { get; set; }

   public string ToJson() {
     return new JavaScriptSerializer().Serialize(this);
   }
 }

 public class Process {
   public string name { get; set; }
   public string value { get; set; }
 }

I create this InputModel in my Controller and pass it to the View:

public ActionResult Input() {
  if (Session["InputModel"] == null)
    Session["InputModel"] = loadInputModel();
  return View(Session["InputModel"]);
}

In my Input.cshtml file I then have some code to generate the input form:

@model PROJ.Models.InputModel

@using(Html.BeginForm()) {
  foreach(PROJ.Models.Process p in Model.axProc){
    <input type="text" />
    @* @Html.TextBoxFor(?? => p.value) *@
  }
  <input type="submit" value="SEND" />
}

Now when I click on the submit button, I want to work with the data that was put into the textfields.

QUESTION 1: I have seen this @Html.TextBoxFor(), but I don't really get this "stuff => otherstuff". I concluded that the "otherstuff" should be the field where I want to have my data written to, in this case it would probably be "p.value". But what is the "stuff" thing in front of the arrow?

Back in the Controller I then have a function for the POST with some debug:

[HttpPost]
public ActionResult Input(InputModel m) {
  DEBUG(m.ToJson());
  DEBUG("COUNT: " + m.axProc.Count);

  return View(m);
}

Here the Debug only shows something like:

{"axProc":[]}
COUNT: 0

So the returned Model I get is empty.

QUESTION 2: Am I doing something fundamentally wrong with this @using(Html.BeginForm())? Is this not the correct choice here? If so, how do I get my model filled with data back to the controller?
(I cannot use "@model List< Process >" here (because the example above is abbreviated, in the actual code there would be more stuff).)

I hope someone can fill me in with some of the details I'm overlooking.

You need to learn what lambda expressions are.

SLaks
– SLaks

2012-05-30 13:33:01 +00:00
Commented May 30, 2012 at 13:33 — SLaks
– SLaks, Commented May 30, 2012 at 13:33
I did, now. Thanks for the name.

Cabadath
– Cabadath

2012-06-07 09:45:54 +00:00
Commented Jun 7, 2012 at 9:45 — Cabadath
– Cabadath, Commented Jun 7, 2012 at 9:45

tkt986 · Accepted Answer · 2012-05-30 16:03:55Z

2

Change your view to some thing like this to properly bind the list on form submission.

@using(Html.BeginForm()) {
  for(int i=0;i<Model.axProc.Count;i++){
   <span>
    @Html.TextBoxFor(model => model.axProc[i].value)
</span>
  }
  <input type="submit" value="SEND" />
}

answered May 30, 2012 at 16:03

tkt986

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1 Comment

Cabadath Over a year ago

Thank you, that works fine. An additional problem I had were further layers, you have to define them as properties (with the {get;set;} stuff), not fields, otherwise it does not work as intended.

m1kael · Accepted Answer · 2012-05-30 15:19:19Z

0

In @Html.TextBoxFor(stuff => otherstuff) stuff is your View's model, otherstuff is your model's public member.
Since in the View you want to render input elements for the model member of a collection type (List), you should first create a separate partial view for rendering a single item of that collection (Process). It would look something like this (name it Process.cshtml, for example, and place into the /Views/Shared folder):
```
@model List<PROJ.Models.Process>

@Html.TextBoxFor(model => p.value)
```

Then, your main View would look like this:

@model PROJ.Models.InputModel

@using(Html.BeginForm()) {
  foreach(PROJ.Models.Process p in Model.axProc){
    @Html.Partial("Process", p)
  }
  <input type="submit" value="SEND" />
}

Also, check that the loadInputModel() method actually returns something, e.g. not an empty list.

answered May 30, 2012 at 15:19

m1kael

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1 Comment

Cabadath Over a year ago

loadInputModel() does return something, the page is correctly rendered (would not be the case if it were empty). But just putting the stuff in partial views does not do the trick, see tsegay's solution.

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