i'm new in Rails and in a controller i have:
class PagesController < ApplicationController
def home
@temp = "Hello"
end
end
I have read that i must put the javascript code in application.js (tell me if true) and i have:
window.onload=function(){alert("<%= j @temp %>")}
Obviously that alert print the string "<%= j @temp %>" How can i pass the variable @temp to the javascript so that the alert can print Hello?
Thanks
I wrote an article on how to pass Ruby objects to the client. Ryan Bates also has an excellent RailsCast on passing data to JS.
Add a div to your view that corresponds to your the PagesControlle#home action that will not be visible when you load the page but will contain the data stored in the Ruby objects:
# views/pages_controllers/home.html.erb
<%= content_tag :div, class: "temp_information", data: {temp: @temp} do %>
<% end %>
Load the page with this div included and view the page source. You can see your Ruby objects stored in the .temp_information div. Open up the JavaScript console to access the Ruby objects as JavaScript objects:
$('.temp_information').data('temp')
You do not need to add your JS to a JS partial, you can also use the asset pipeline.
I do something similar to, but simpler than gon. I have the following in my ApplicationController.
def javascript_variables(variables)
@javascript_variables ||= {}
@javascript_variables.merge!(variables)
end
Within a controller action I can then do something like
def some_action
javascript_variables(user: current_user)
end
In my ApplicationHelper I have something like this
def javascript_variables(variables = nil)
@javascript_variables ||= {}
@javascript_variables.merge!(variables) and return if !variables.nil?
output = ''
padding = @javascript_variables.keys.group_by(&:size).max.first
@javascript_variables.each do |variable, value|
output << "#{variable.to_s.ljust(padding)} = #{value.to_json},\n "
end
raw "var " + output.strip.html_safe.gsub(/\,\Z/m, ';')
end
and finally in my layout's <head> I have
<script>
<%= javascript_variables %>
</script>
This gives me something like this (from a real example in my application)
<script>
var pageModule = "site/index",
isCustomer = false,
utype = "normal",
isAnonymous = true,
keyboardShortcuts = false,
pubnub = null,
requestToken = "3zj974w074ftria3j";
</script>
@javascript_variables ||= {} \n @javascript_variables.merge!(variables) if !variables.nil? \n return if @javascript_variables == {} I have used \n just to split code lines in comment.Take a look at this.
http://tech.thereq.com/post/17243732577/rails-3-using-link-to-remote-true-with-jquery-ujs
One of the easiest ways is to use js.erb file, where you can do ruby tags to access variables that you defined in the controller action.
You need to use a respond_to block in the controller action, specifying the action to be able to respond to javascript.
items_controller.rb
class ItemsController < ApplicationController
def action
respond_to do |format|
format.js
#format.html {} # These are for allowing other types of formats to be responded to.
#format.json {} # But they are not necessary for using this js.erb way of doing things.
end
end
end
/views/items/action.js.erb
$(div).html('The cat has erased your page');
