json format in ruby on rails? - ruby-on-rails-3

Question

How to send data in database and show in needed part by using json format in ruby on rails3?
my form is like this
<%= form_for(#user) do |f| %>
<% if #user.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(#user.errors.count, "error") %> prohibited this user from being saved:</h2>
<ul>
<% #user.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="field">
<%= f.label :name %><br />
<%= f.text_field :name %>
</div>
<div class="field">
<%= f.label :email %><br />
<%= f.text_field :email %>
</div>
<div class="field">
<%= f.label :login %><br />
<%= f.text_field :login %>
</div>
<div class="actions">
<%= f.submit %>
</div>
<% end %>

Answer 1

In the controller:
def show
#user = User.find(params[:user_id]
respond_to do |format|
format.json { :render => #user }
end
end
You can customise the JSON output by overriding the as_json in the User model:
def as_json(options=false)
self.include_root_in_json = false
options = (options || {}).reverse_merge(
:except => [:updated_at, :created_at, :id],
:include => :some_association
)
super(options)
end