Question

When the view pass the parameters to controller,
controller gets nil for all of the arguements somehow.

Can anyone how to fix this?? Thanks!

and I have no model called “Message”

controllers/messages_controller.rb

  def deliver

   recipient = User.find_by_username(params[:recipient])
   subject = params[:subject]
   body = params[:body]

   current_user.send_message(recipient, body, subject)
    redirect_to :controller => 'messages', :action => 'received' 
    flash[:notice] = "message sent!"

  end

views/messages/new.html.erb

<%=form_for :messages, url: url_for( :controller => :messages, :action => :deliver ) do |f| %>
    <div class="field">
      <%= f.label :subject %><br />
      <%= f.text_field :subject %>
    </div> 

    <div class="field">
      <%= f.label :body %><br />
      <%= f.text_field :body %>
    </div> 

  <div class="actions">
    <%= f.submit %>

<% end %>

Answer 1

Check your source HTML to better understand what FormHelpers do.

With the form_for f.text_field will generate names attributes in the format:

messages[subject]

Consequently, your params will be in the format:

params[:messages][:subject]

You can also use <%= debug params %> to inspect what’s in params, it’s very helpful.