Javascript: How to iterate through list of objects in Model

Question

so I need to get to fetch the names of students in a list of student object that is in a view's model then send them to the server via $.post, the latter I have figured it out but I can't figure out how to iterate through the list of objects. Basically I have this:

//Student object
public class Student 
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    //Like a bunch of other attributes here
} 

This is the model in the view:

//StudentSearchResult ViewModel

public class StudentSearchResult {

    public IEnumerable<Student> { get; set;}
}

At first I though of just sending the student list object as is, but it may not be a good idea as it is bundled with too many attributes (it gave me this 'circular' error when I tried to send the model) and I only really need to send the concatenated FirstName and LastName to the controller using the $.post method I already have. I tried things like these:

var names = []  
var length = "@Model.StudentSearchResult.count()";  
for (int i = 0; i < length; i++) 
{
     names[] = "@Model.StudentSearchResult[i].Name + @Model.StudentSearchResult[i].LastName"
}
//$.post function here that calls the controller and send the concatenated names of each student in studentsearchresult.

But I'd get an error that "i" doesn't exists so, how can I iterate in javascript through the list of objects in my view model, access the atributes and concatenate them and then store them on an array of strings so that I may send it to the controller? I imagine the controller would look like this

[HttpPost]
public ActionResult StudentSearchResult(/*other stuff I send here, */ string[] studentNames){
   //stuff here

  return View();
}

Thanks!

Solution 1

You have some invalid javascript over there.

First start by fixing your view model so that you have a compiling C# code (you were missing a property name):

public class StudentSearchResult 
{
    public IEnumerable<Student> Students { get; set;}
}

Then assuming your controller actions sends a JSON result to the client (this ensures that the view model is properly JSON encoded and that the application/json response content type header is sent):

[HttpPost]
public ActionResult StudentSearchResult(/*other stuff I send here, */ string[] studentNames)
{
    StudentSearchResult model = ... //stuff here to populate your view model
    return Json(model);
}

you could easily iterate on the client using the $.each() function:

var studentNames = ['name1', 'name2'];
$.post('/Students/StudentSearchResult', studentNames, function(result) {
    var students = result.Students;
    $.each(students, function() {
        alert('FirstName: ' + this.FirstName + ' LastName:' + this.LastName);
    });
});

or even a plain ol' for loop if you prefer:

$.post('/Students/StudentSearchResult', studentNames, function(result) {
    var students = result.Students;
    for (var i = 0; i < students.length; i++) {
        var student = students[i];
        alert('FirstName: ' + student.FirstName + ' LastName:' + student.LastName);
    }
});

---

UPDATE:

It looks like I have I made a mistake by believing that you were performing an AJAX request. Instead what you need is access the model properties in javascript. Here's how this could be done:

@model StudentSearchResult
<script type="text/javascript">
    var students = @Html.Raw(Json.Encode(Model.Students));
    // students is a javascript array that will look like this:
    // students = [{"FirstName":"fn1","LastName":"ln1"}, {"FirstName":"fn2","LastName":"ln2"}, ...];
    for (var i = 0; i < students.length; i++) {
        var student = students[i];
        alert('FirstName: ' + student.FirstName + ' LastName:' + student.LastName);
    }
</script>

Solution 2

you can use $.each of jquery to iterate the result.

$.each(yourModel,function(){//do with loop});

and for the error. you made mistake in declaration of loop variable

for (var i = 0; i < length; i++) 

Solution 3

Looks like what you need is to output the user names to the client as JSON? Try this:

var names = @Model.StudentSearchResult.Select(s => new { s.FirstName, s.LastName }).ToList();

I'm not quite familiar with the Razor syntax, but I think you can still understand the code above.

Comments

[Ricardo]

Thank you for your answer but the post function doesn't return a model, I know this is because I didn't post the complete code but I didn't have it at hand.

[Ricardo]

In your $.each example, how would you introduce the elements in an array if you're not taking the model from the post but from the view model itself, I am trying this: var names = new Array(); var candidates = "@Model.Candidates"; //It doesn't lets me do this for (var i = 0; i < candidates.length; i++) { var candidate = candidate[i]; alert('FirstName: ' + candidate.Name + ' LastName:' + candidate.LastName); } All I need is to populate an array with the first and last name

[Ricardo]

Since I am using razor to access my view model I get the error that the variable "i" can't be found

[Darin Dimitrov]

I understand. Please see my updated answer with an example of how you could achieve that.