Dropdown selector, selected option

I am using Ruby on Rails version 3. I have defined the following helper method for a selector:

  def current_user_selector
    collection_select(:user, :id, User.all, :id, :name, {:prompt => "Select a User"});
  end

I have introduced the aforementioned selector in my index.html.erb:

...
<%= current_user_selector %>
...

I've read somewhere that the selected option from the dropdown menu could be accessed in the controller with:

selected_user = params[user][id]

I have added the above line in several actions of my controller but I keep getting exceptions.

Currently I have it in the following action:

  # GET /users/:id/click
  # GET /users/:id/click.xml
  def click
    @user = User.find(params[:id])
    @users_to_click = User.where("clicks_given - clicks_received >= ?", -5).order("clicks_given - clicks_received")
    selected_user = params[user][id]

    respond_to do |format|
      format.html # click.html.erb
      format.xml  { render :xml => @user }
    end
  end

My question i开发者_如何学JAVAs, how and I get the selected user of the dropdown menu.

Naren Sisodiya led me to the following exception:

You have a nil object when you didn't expect it!
You might have expected an instance of ActiveRecord::Base.
The error occurred while evaluating nil.[]

params[:user][:id] will give you id of selected user, so you need to find the user using this id.

selected_user = User.find(params[:user][:id])

EDIT:

also make sure that you are accessing it as params[:user][:id] instead params[user][id]

Update:

you need to pass the selected value to server, as you mentioned you have a button that invokes the click action. Now you can create a from with dropdown and one submit button; something as

<%= form_tag('/click',:method=>'get') do -%>
 <%= current_user_selector %>
 <%= submit_tag 'Get Selected' %>
<% end -%>