Question

I found a workaround for errors parsing JSON strings sent from (Firefox) browser using JSON.parse() in my controller, but isn’t there a better solution?

rails 2.3.12
json (1.6.1)   

---

View –> Controller

---

views/theme_maps/edit.html.erb:

(javascript)

var labels = ["4", "5"];
document.getElementById("labels").value = JSON.stringify(labels);

(html)

<% form_for(@theme_map}) do |f| %>  
<input type="hidden" id='labels' name='labels' />  
<%= f.submit 'Update' %>  
<% end %>  

---

theme_maps_controller#update:

(ruby)

  labels = params[:labels]     # get it from the hidden field  

the problem, and my hack solution, is here:

  #   labels.inspect returns: "\"[\\\"4\\\", \\\"5\\\"]\""  
  #   JSON.parse(labels) throws an exception.  
  labels.gsub!('"[', '[')  # remove the quotes  
  labels.gsub!(']"', ']')  # around the brackets.  
  labels.gsub!('\\', '')   # remove the escaped backslash.  
  #   now labels.inspect returns:  "[\"4\", \"5\"]"  

  labels_array = JSON.parse(labels) 
  #   now it's happy. 

---

Controller –> View

---

Just to round things out, and because it took me ages to figure this out:

theme_maps_controller#edit:
(ruby)

  label_list = ["1", "2","3"]
  @json_labels = label_list.to_json  

---

views/theme_maps/edit.html.erb:

(javascript)

  var exist_labels = <%= @json_labels %>;

Answer 1

The problem is using JSON.stringify(). What is needed is .toSource().

var labels = ["4", "5"];
// document.getElementById("labels").value = JSON.stringify(labels);
document.getElementById("labels").value = labels.toSource();