active_record回调过程

activesupport-2.3.4/lib/active_support/callbacks.rb

activerecord-2.3.4/lib/active_record/callbacks.rb

activerecord-2.3.4/lib/active_record/transactions.rb

models/topic.rb

activerecord-2.3.4/lib/active_record/callbacks.rb

[:create_or_update, :valid?, :create, :update, :destroy].each do |method|
        base.send :alias_method_chain, method, :callbacks
end

[:create_or_update, :valid?, :create, :update, :destroy].each do |method|
        base.send :alias_method_chain, method, :callbacks
end

def after_create() end
   def create_with_callbacks #:nodoc:
     return false if callback(:before_create) == false
     result = create_without_callbacks
     callback(:after_create)
     result
   end
   private :create_with_callbacks

 def after_create() end
    def create_with_callbacks #:nodoc:
      return false if callback(:before_create) == false
      result = create_without_callbacks
      callback(:after_create)
      result
    end
    private :create_with_callbacks

activesupport-2.3.4/lib/active_support/callbacks.rb

def define_callbacks(*callbacks)
        callbacks.each do |callback|
          class_eval <<-"end_eval"
            def self.#{callback}(*methods, &block)
              callbacks = CallbackChain.build(:#{callback}, *methods, &block)
              @#{callback}_callbacks ||= CallbackChain.new
              @#{callback}_callbacks.concat callbacks
            end

            def self.#{callback}_callback_chain
              @#{callback}_callbacks ||= CallbackChain.new

              if superclass.respond_to?(:#{callback}_callback_chain)
                CallbackChain.new(
                  superclass.#{callback}_callback_chain +
                  @#{callback}_callbacks
                )
              else
                @#{callback}_callbacks
              end
            end
          end_eval
        end
      end

def define_callbacks(*callbacks)
        callbacks.each do |callback|
          class_eval <<-"end_eval"
            def self.#{callback}(*methods, &block)                             
              callbacks = CallbackChain.build(:#{callback}, *methods, &block)  
              @#{callback}_callbacks ||= CallbackChain.new                     
              @#{callback}_callbacks.concat callbacks                          
            end                                                                
            def self.#{callback}_callback_chain                                
              @#{callback}_callbacks ||= CallbackChain.new                     
              if superclass.respond_to?(:#{callback}_callback_chain)     
                CallbackChain.new(                                           
                  superclass.#{callback}_callback_chain +                    
                  @#{callback}_callbacks                                      
                )                                                           
              else                                                           
                @#{callback}_callbacks                               
              end                                                              
            end                                                             
          end_eval
        end
      end

def run_callbacks(kind, options = {}, &block)
      self.class.send("#{kind}_callback_chain").run(self, options, &block)
    end

def run_callbacks(kind, options = {}, &block)
      self.class.send("#{kind}_callback_chain").run(self, options, &block)
    end

activerecord-2.3.4/lib/active_record/transactions.rb

base.class_eval do
       [:destroy, :save, :save!].each do |method|
         alias_method_chain method, :transactions
       end
     end

 base.class_eval do
        [:destroy, :save, :save!].each do |method|
          alias_method_chain method, :transactions
        end
      end

models/topic.rb

after_create    :clear_cache

after_create    :clear_cache

base.rb

def save
        create_or_update
end

def save
        create_or_update
end

def create_or_update
        raise ReadOnlyRecord if readonly?
        result = new_record? ? create : update
        result != false
end

def create_or_update
        raise ReadOnlyRecord if readonly?
        result = new_record? ? create : update
        result != false
end

def create
        if self.id.nil? && connection.prefetch_primary_key?(self.class.table_name)
          self.id = connection.next_sequence_value(self.class.sequence_name)
        end

        quoted_attributes = attributes_with_quotes

        statement = if quoted_attributes.empty?
          connection.empty_insert_statement(self.class.table_name)
        else
          "INSERT INTO #{self.class.quoted_table_name} " +
          "(#{quoted_column_names.join(', ')}) " +
          "VALUES(#{quoted_attributes.values.join(', ')})"
        end

        self.id = connection.insert(statement, "#{self.class.name} Create",
          self.class.primary_key, self.id, self.class.sequence_name)

        @new_record = false
        id
      end

def create
        if self.id.nil? && connection.prefetch_primary_key?(self.class.table_name)
          self.id = connection.next_sequence_value(self.class.sequence_name)
        end
        quoted_attributes = attributes_with_quotes
        statement = if quoted_attributes.empty?
          connection.empty_insert_statement(self.class.table_name)
        else
          "INSERT INTO #{self.class.quoted_table_name} " +
          "(#{quoted_column_names.join(', ')}) " +
          "VALUES(#{quoted_attributes.values.join(', ')})"
        end
        self.id = connection.insert(statement, "#{self.class.name} Create",
          self.class.primary_key, self.id, self.class.sequence_name)
        @new_record = false
        id
      end