Rails: Add user to project's users collection

Question

I've got project and user models with belongs_and_has_many in them. Now I need add specific user into project's collection. I've got method in projects controller:

def addfriend
  @project = Project.find(params[:id])
  @project.users << User.find(params[:user])
  respond_to do |format|
    format.html { redirect_to project, :notice => 'Added.' }
  end
end

and I've got this code in show.html.erb of project:

<select id="user_select" name="user_select" class="input-large">
  <% @users.each do |user| %>
    <option><%= user.username %></options>
  <% end %>
</select>
<!-- button to addfriend method here -->

Now, I need to add button on mark in code (or somewhere else) with calling that "addfriend" method.

In routes.rb I've got:

 resources :projects do
   collection do
     get :addfriend
   end
 end

Answer 1

Assuming you have an @project variable defined somewhere:

<%= link_to 'Add friend', addfriend_project_path(@project, user_id: user.id) %>

In your Projects controller action change the 2 firsts lines for this:

project = Project.find(params[:id])
@project.users << User.find(params[:user_id])

And in your routes:

resources :projects do
  member do
      get :addfriend
  end
end