Using the lib folder for application parts in rails - ruby-on-rails

Question

there are some problems with Ruby on Rails I couldn't solve even spending hours and hours trying. I hope you guys can help me. The four questions are marked with Q1-Q4 at beginning of line.
I have an element in the view that I need more than once. For this reason there should be a separate module in the lib folder (so I can use it in an other project too).
What I need:
- A helper method that I can call automatically from any view.
- Since it requires more html stuff, I want to use an html file, which I render in the helper-method.
- Pass parameters to a javascript file.
- If the element is used, the JavaScript file must be included
- If the element is used, the CSS file must be included
Since it isn't easy to understand what I mean, I'll explain it again with a simple example (it's just an example, so don't think to much about its sence): Helper for creating a combo box with a view-helper or alternatively with a javascript method.
Clearly, I need
(html) - a text input field placed on top of a drop down box
(js) - a function that displays the selected item of the drop-down box in the text box.
(css) - the style of the text box positioned in front of the drop down.
(settings) - a settings file that initializes the element so that I can use it everywhere automatically.
The folder structure which I imagine:
lib
combo_box
combo_box_helper.rb
_combo_box.html.erb
combo_box.js
combo_box.css
At the combo_box-helper.rb I have 2 Methods:
combo_box_field(drop_down_content)
The method gives back a combobox using the partial. The array entries are available in the drop down box.
combo_box_js(drop_down_content)
The method must be called when a combo box is to be created using javascript. To make changes to the combobox only once, the element should also be created with the partial and passed to javascript.
Here appear the first problem:
Q1: At the first call (and only on the first call) of any method, it have to include the js and css file. What is the common way to do this?
Q2: How can I render a partial that is located in the lib folder and not in the app/view folder?
Q3: What is the common way to pass parameters to javascript?
My first try:
module ComboBoxHelper
def combo_box_field(drop_down_content)
output = check_first_call
output + render(:partial => 'combo_box', :locals => {:content => drop_down_content})
end
def
output = check_first_call
output + "<div class='hidden' data-combobox = '" + render(:partial => 'combo_box', :locals => {:content => drop_down_content}) + "'></div>"
end
def check_first_call
if #already_called
""
else
#already_called = true
javascript_include_tag("combo_box.js") + stylesheet_link_tag("combo_box.css")
end
end
end
Problems:
render-method doesn't work (it searches in app/view for the partial)
the call of check_first_call is ugly. especially as it returns a string.
the includes of javascript and css don't work (the files aren't in the asset pipeline)
The content of the .html.erb and .css files is self-explanatory.
Interesting part of the javascript file is my attempt to access parameters passed by Ruby on Rails:
$('div.hidden[data-combobox]').data("combobox")
If these problems are solved, only one thing is important:
How do I initialize the module correctly, so I use it automatically everywhere.
My first try:
I create a file at the folder config/initializers/init_combo_box with that code:
require_dependency 'combo_box/combo_box_helper'
ActiveSupport.on_load(:action_view) do
include ComboBoxHelper
end
Q4: Is this the common way? Do I have something to add to solve one of the above problems (for example the add the js- and css-files to the asset pipeline)?
Thanks for your help.