Passing variable value form js function to rails view (dynamic select)

Question

Hi, I'm using Ryan's solution to add and remove nested model fields dynamically through JavaScript using jQuery.

There are 4 models: client, c_person; project, p_person. And one-to-many associations: client has many c_people and project has many p_people (these are people from client side but they belongs to project). Hope it isn't too complicated example)

So, I have following problem, please help:

When I'm using helper method "link_to_add_fields" in my view, I need to pass another parameter (current_client_id) that depends of what client is currently selected in select box.

<!-- new.html.erb -->
<p>
<%= f.label :client_id %></br>
<%= f.collection_select :client_id, Client.order("title"), :id, :title %>
</p>
<p>
<%= f.fields_for :p_people do |builder| %>
<%= render "p_person_fields", :f => builder %>
<% end %>
</p>
<p><%= link_to_add_fields "Add Person", f, :p_people, current_client_id %></p>

I need that to dynamically change the collection for @people variable in helper method,

# application_helper.rb
def link_to_add_fields(name, f, association, current_client_id)
    new_object = f.object.class.reflect_on_association(association).klass.new
    @people = CPerson.where(:client_id => current_client_id).order(:name) unless current_client_id.blank?
    fields = f.fields_for(association, new_object, :child_index => "new_#{association}") do |builder|
      render(association.to_s.singularize + "_fields", :f => builder)
    end
    link_to_function(name, h("add_fields(this, \"#{association}\", \"#{escape_javascript(fields)}\")"))
end

to finally use it in partial:

<!-- _p_person_fields.html.erb -->
<div class="fields">
<p>
<%= f.collection_select :content, @people, :name, :name %>
<%= f.hidden_field :_destroy %>
<%= link_to_function "Remove", "remove_fields(this)" %>
</p>
</div>

I've implemented simple js function to get current_client_id value, but I don't know how to pass it to my view or helper method.

// application.js
function current_client_id() {
var current_client_id = $("select#client_id :selected").val();
}

I appreciate your help! Maybe there is a better solution?

Answer 1

One thing I don't like about this is that you're using logic in a view helper that really belongs in your controller.

Maybe a better approach would be to make an AJAX call to a controller with the current_client_id. That controller can then get the @people object and send back a js.erb template where you can append a partial to your view. Or it could send back a JSON object and the handler to your AJAX call will create new elements to add to the DOM.