crud_controller.rb

class CrudController < ApplicationController
  
  # GET /<models>
  # GET /<models>.json
  def index
    respond_with call_on_model(:scoped)
  end

  # GET /<models>/1
  # GET /<models>/1.json
  def show
    respond_with find_on_model params[:id]
  end

  # GET /<models>/new
  # GET /<models>/new.json
  def new
    respond_with call_on_model(:new)
  end

  # GET /<models>/1/edit
  def edit
    respond_with find_on_model params[:id]
  end

  # POST /<models>
  # POST /<models>.json
  def create
    @obj = call_on_model(:new, params[model_name.to_sym])
    respond_to do |format|
      if @obj.save
        respond_with @obj
      else
        format.html { render :action => "new" }
        respond_with @obj.errors
      end
    end
  end

  # PUT /<models>/1
  # PUT /<models>/1
  # PUT /<models>/1.js
  def update
    
    @obj = find_on_model params[:id]
    
    respond_to do |format|
      if @obj.update_attributes(params[model_name.to_sym])
        respond_with @obj
      else
        format.html { render :action => "edit" }
        format.json respond_with @obj.errors
      end
    end

  end

  # DELETE /<models>/1
  # DELETE /<models>/1.json
  def destroy
    (find_on_model params[:id]).destroy
    respond_to do |format|
      format.html { redirect_to(model_name.pluralize+'_url') }
      format.json { head :ok }
    end
  end
  
private

  def get_model_name
    nil
  end

  def model_name
     get_model_name || self.class.to_s.gsub(/Controller$/, '').singularize
  end
  
  def find_on_model *args 
    call_on_model(:find, *args)
  end
  
  def call_on_model meth, *args
    User.send(meth, *args)
  end

end