How to make Ruby code fetched from DB work in JS?

Question

I am using rails code to populate some html and JS code into mysql DB. The code is then fetched from DB and rendered on a configurable page. In the HAML file, When I use ruby code in a JS alert it works fine:

alert("#{user.id}")

the id is displayed because I pass the user object to this page. Now when I save this line alert("#{user.id}") in DB and render the JS code, it alerts #{user.id} as a string. How do I make it realize that the string coming from DB is not just a string, it is some ruby code which needs to be interpreted on the page as I am getting the user object there. So it should display the actual id like 5 or 6 instead of showing a simple string "#{user.id}"

Plz help

vikhyat · Accepted Answer · 2012-06-20 09:16:12Z

1

If it is okay to change the syntax (something like alert("<%= user.id %>")), you can use ERB or some other similar templating engine.

Here's how to do it with ERB.

require 'erb'
user_id = 23
str = 'alert("<%= user_id %>")' # get these from the database
ERB.new(str).result(binding)

Note that this is dangerous because it means that users can actually run code from within the ERB.

To get around this I suggest using another templating language.

Here are some options:

edited Jun 20, 2012 at 9:16

answered Jun 20, 2012 at 9:05

vikhyat

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2 Comments

user1468464 Over a year ago

thanks for the answer. In my case, I am using this on the page where I want to display the ruby + JS code #{raw decode_entities configurable_page.js_for_body} with this line all the script that is saved in the db is rendered on the page. so all the changes I have to make in the db field not on the haml page. On the haml page I only use one line code to display all JS code that is available .

vikhyat Over a year ago

So before rendering the JS onto the page, I guess you would pass it through one of the templating engines I listed above?

Someth Victory · Accepted Answer · 2012-06-20 08:23:28Z

0

There are a few way to do in order to pass data from Rails to JS, see the video here:

http://railscasts.com/episodes/324-passing-data-to-javascript?view=comments

answered Jun 20, 2012 at 8:23

Someth Victory

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Comments

Wawa Loo · Accepted Answer · 2012-06-20 08:54:00Z

0

Personally, I store the data in a hidden field in my view, then work with it with jQuery.

=form_for :user do |f|
  =f.hidden_field :id

Then in javascript

$('document').ready ->
  alert $('#user_id').val()

answered Jun 20, 2012 at 8:54

Wawa Loo

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