new_scaffold.rb

class UsersController < ApplicationController
  respond_to :html, :xml

  # GET /users
  # GET /users.xml
  def index
    @users = User.all
    respond_with(@users)
  end

  # GET /users/1
  # GET /users/1.xml
  def show
    @user = User.find(params[:id])
    respond_with(@user)
  end

  # GET /users/new
  # GET /users/new.xml
  def new
    @user = User.new
    respond_with(@user)
  end

  # GET /users/1/edit
  def edit
    @user = User.find(params[:id])
  end

  # POST /users
  # POST /users.xml
  def create
    @user = User.new(params[:user])

    respond_to do |format|
      if @user.save
        flash[:notice] = 'User was successfully created.'
        format.html { redirect_to(@user) }
        format.xml  { render :xml => @user, :status => :created, :location => @user }
      else
        format.html { render :action => "new" }
        format.xml  { render :xml => @user.errors, :status => :unprocessable_entity }
      end
    end
  end

  # PUT /users/1
  # PUT /users/1.xml
  def update
    @user = User.find(params[:id])

    respond_to do |format|
      if @user.update_attributes(params[:user])
        flash[:notice] = 'User was successfully updated.'
        format.html { redirect_to(@user) }
        format.xml  { head :ok }
      else
        format.html { render :action => "edit" }
        format.xml  { render :xml => @user.errors, :status => :unprocessable_entity }
      end
    end
  end

  # DELETE /users/1
  # DELETE /users/1.xml
  def destroy
    @user = User.find(params[:id])
    @user.destroy

    respond_to do |format|
      format.html { redirect_to(users_url) }
      format.xml  { head :ok }
    end
  end
end

old_scaffold.rb

class UsersController < ApplicationController
  # GET /users
  # GET /users.xml
  def index
    @users = User.all

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

  # GET /users/1
  # GET /users/1.xml
  def show
    @user = User.find(params[:id])

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

  # GET /users/new
  # GET /users/new.xml
  def new
    @user = User.new

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

  # GET /users/1/edit
  def edit
    @user = User.find(params[:id])
  end

  # POST /users
  # POST /users.xml
  def create
    @user = User.new(params[:user])

    respond_to do |format|
      if @user.save
        flash[:notice] = 'User was successfully created.'
        format.html { redirect_to(@user) }
        format.xml  { render :xml => @user, :status => :created, :location => @user }
      else
        format.html { render :action => "new" }
        format.xml  { render :xml => @user.errors, :status => :unprocessable_entity }
      end
    end
  end

  # PUT /users/1
  # PUT /users/1.xml
  def update
    @user = User.find(params[:id])

    respond_to do |format|
      if @user.update_attributes(params[:user])
        flash[:notice] = 'User was successfully updated.'
        format.html { redirect_to(@user) }
        format.xml  { head :ok }
      else
        format.html { render :action => "edit" }
        format.xml  { render :xml => @user.errors, :status => :unprocessable_entity }
      end
    end
  end

  # DELETE /users/1
  # DELETE /users/1.xml
  def destroy
    @user = User.find(params[:id])
    @user.destroy

    respond_to do |format|
      format.html { redirect_to(users_url) }
      format.xml  { head :ok }
    end
  end
end

respond_with_verb_semantics.rb

# This does not work in Rails master. This is a proposal to make respond_with
# completely resourceful so the developer just have to worry with non behavior
# (aka html).
#
# respond_with is checks the action VERB (GET, POST, PUT or DELETE) and acts
# accordingly.
#
# That said, if you are building an API, that is enough for a create action:
#
#   def create
#     @user = User.new(params[:user])
#     @user.save
#     respond_with(@user)
#   end
#
# If user has no errors (@user.errors.empty? is true), it will respond with
# status created (201) and set the location to the user_url(@user).
#
# If user have errors, it will render the @user.errors with unprocessable
# entity status (422).
#
# Below you have some examples if you need to add html behavior.
#
class UsersController < ApplicationController
  respond_to :html, :xml, :json

  # GET /users
  # GET /users.xml
  def index
    @users = User.all
    respond_with(@users)
  end

  # GET /users/1
  # GET /users/1.xml
  def show
    @user = User.find(params[:id])
    respond_with(@user)
  end

  # GET /users/new
  # GET /users/new.xml
  def new
    @user = User.new
    respond_with(@user)
  end

  # GET /users/1/edit
  def edit
    @user = User.find(params[:id])
  end

  # POST /users
  # POST /users.xml
  def create
    @user = User.new(params[:user])

    respond_with(@user) do |format|
      if @user.save
        flash[:notice] = 'User was successfully created.'
        format.html { redirect_to(@user) }
      else
        format.html { render :action => "new" }
      end
    end
  end

  # PUT /users/1
  # PUT /users/1.xml
  def update
    @user = User.find(params[:id])

    respond_with(@user) do |format|
      if @user.update_attributes(params[:user])
        flash[:notice] = 'User was successfully updated.'
        format.html { redirect_to(@user) }
      else
        format.html { render :action => "edit" }
      end
    end
  end

  # DELETE /users/1
  # DELETE /users/1.xml
  def destroy
    @user = User.find(params[:id])
    @user.destroy

    respond_with(@user) do |format|
      format.html { redirect_to(users_url) }
    end
  end
end