Question

I understand what is passed to the form_for method when doing something like :

<% form_for(@user) do |f| %> ... <% end %>

if @user is set in the controller. This is pretty obvious.

But what happens when we pass :user, as I have seen in many examples ?

<% form_for(:user) do |f| %> ... <% end %>

When should I use the symbol version ?

Answer 1

Using the symbol will generate:

<form action="/users" method="post">

Using the object @user set to new you get:

<form action="/users" class="new_user" id="new_user" method="post">

If you set @user to something else it will change the form tag generated, of course
… try it out for yourself.

In the end it all depends what you’re trying to do. You might want to use the symbol if you have multiple :user forms on the same page.