What is the best way to integrate Ruby code retrieved from a database into JavaScript?

Utilizing rails code to insert HTML and JS into a MySQL database, the rendered code is extracted from the DB and displayed on a customizable page. In the HAML file, embedding Ruby in a JS alert functions correctly:

alert("#{user.id}")

The ID is visible as the user object is passed to this page. However, saving alert("#{user.id}") in the DB and rendering the JS code results in #{user.id} being shown as a string. How can I ensure that the string retrieved from the DB is recognized as Ruby code to be interpreted on the page, revealing the actual user ID like 5 or 6 rather than displaying it as a simple string "#{user.id}"?

Please assist.

javascriptruby-on-railsruby

Answer №1

If you are open to modifying the syntax (such as alert("<%= user.id %>")), there are options like ERB or similar templating engines available.

Below is an example using ERB:

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

It is important to note that this approach can be risky as it allows users to execute code within the ERB.

To mitigate this risk, I recommend exploring other templating languages. Here are some alternatives:

Answer №2

If you're looking to transfer information from Rails to JS, there are various methods available. Check out this video for a detailed explanation:

Answer №3

In my personal approach, I prefer saving the information in a concealed field within the interface and utilizing jQuery to manipulate it.

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

Afterwards, in the javascript section:

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

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