Question

I am trying to create an online survey.

I have a View where a user can create a Multiple Choice question with as many answer possibilities as the user wishes. Each answer possibility is supposed to have text boxes which represents the following properties:

[Multiple_Choice_Question]
int choice_number { get; set; } // The order in which the MCQ answer possibility is shown
int choice_wording { get; set; } // The MCQ answer possibility
string help_text { get; set; } // help_text if the user doesnt understand the answer possibility

How should my ViewModel look like, when i dont know how many answer possibilities the user wants?

Thanks

Answer 1

Use javascript and the JSON model binding in MVC3 to help you here.

On the client side create a javascript “object” that matches your server side object

function MultipleChoiceQuestion(choice_number, choice_wording, help_text)
{
    this.ChoiceNumber = choice_number;
    this.ChoiceWording = choice_wording;
    this.HelpText = help_text;
}

Then use javascript to iterate and parse through the DOM to get the variable number of answers.

psuedo-code…

var ListOfQuestions = [];
foreach(some dom elements)
{
    var cn = dom.choiceNumber;
    var cw = dom.choiceWording;
    var ht = dom.helpText;

    var question = new MultipleChoiceQuestion(cn, cw, ht);
    ListOfQuestions.push(question);

}

Post this with ajax. One downside to this method is that you have to use ajax.

$.ajax({
   url:"/yoursite/controller/action",
   type:"POST",
   data: JSON.stringify(ListOfQuestions),
   dataType: 'json',
   contentType: 'application/json, charset=utf-8',
   success: function(data){},
   error: function(){}

});

Then on the server side you have your question class as you’ve already defined it(your property names must match the client side property names), and a container class…

public class QuestionContainer()
{
    public List<MultipleChoiceQuestion> Questions {get; set;
}

and your Action takes this as a parameter

public ActionResult Create(QuestionContainer questions)
{

    ...
}

Phil Haack did an article about this, but before the MVC3 binding was released. It’s easier now than what he wrote about.

http://haacked.com/archive/2010/04/15/sending-json-to-an-asp-net-mvc-action-method-argument.aspx