Rails select with multiple options only sends one - ruby-on-rails

Question

I have this form :
<form accept-charset="UTF-8" action="/contracts/<%= params[:id] %>/addConsultants" method="POST" id="updateConsultants"><!---->
<div style="margin:0;padding:0;display:inline">
<input name="utf8" type="hidden" value="✓">
<input name="authenticity_token" type="hidden" value="<%= session[:_csrf_token] %>">
</div>
<div class="consultant_selector">
<h2>Consultants</h2>
<select name="consultants_available" size="10" multiple>
<% #users.each do |u| %>
<option value="<%= u[:id_user] %>"><%= u[:name] %></option>
<% end %>
</select>
<ul>
<li class="triangle_right" id="add_consultant"></li>
<li class="triangle_left" id="remove_consultant"></li>
</ul>
<select name="consultants_selected" size="10" multiple>
</select>
</div>
<div>
<input type="submit" value="Mettre à jour" />
</div>
</form>
And in my controller :
def add_consultants
#contract = Contract.find(params[:id])
#consultants = params[:consultants_selected];
puts "------ Consultants: #{#consultants}"
redirect_to contract_path
end
The idea is that I can select names from the first select, move them to the second by clicking on the triangle and then submit the form to assign these names to a contract. However, when I do this the call to puts only prints one ID out of the 3 I have in the second select (all three of them have the selected attribute to true). How do I get multiple values?

Answer 1

Just found the answer here : https://stackoverflow.com/a/2196522/1796742
Changing the name of the second select from:
<select name="consultants_selected" size="10" multiple>
</select>
To :
<select name="consultants_selected[]" size="10" multiple>
</select>
Worked.