Can I change the instance variable using ajax in rails?

Question

I have used ajax to get the object from controller.

  $('#city').on('change',function(){
    $.ajax({
      url: "/courses/index",
      type: "GET",
      data: {city: $('#city').val() },
      success: function(responseData) {
        alert(responseData);
      }
    });

So the responseData is the json format collection of the courses.

Currently, I have a html code: <%= @courses.first.name %>

How to modify the @courses instance which the result is the responseData of ajax.

Thanks.

Richard Peck · Accepted Answer · 2016-01-10 13:05:58Z

1

You can't change the instance variable, because that belongs to the instance of the Ruby class you're using.

Using ajax invokes a new instance of your respective classes (on the server); javascript only works with the front-end view (HTML code / DOM), so you have to populate that with the response:

$(document).on('change', '#city', function(){
    $.ajax({
      url: "/courses/index",
      type: "GET",
      data: {city: $('#city').val() },
      success: function(responseData) {
        course = JSON.parse(responseData);
        $(".element").html(course.name);
      }
    });
});

Without knowing which data you're expecting back etc, it's kind of tough to know how to "parse" your data. However, the important thing to note is that you should not be trying to change the ERB, instead identify the html and replace it with the JSON you receive back.

Also, you'll need to use something like JSON.parse to create a workable object in your javascript (which you can then use to populate your page with).

answered Jan 10, 2016 at 13:05

Richard Peck

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1 Comment

Stephen Over a year ago

Thanks for you explain.

Daniel · Accepted Answer · 2016-01-10 07:27:41Z

0

Sounds like you want to POST the information back to the rails application via Ajax.

answered Jan 10, 2016 at 7:27

Daniel

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