一个action的process过程

ruby 代码

def process(request, response, method = :perform_action, *arguments) #:nodoc:
   initialize_template_class(response)
   assign_shortcuts(request, response)
   initialize_current_url
   assign_names
   forget_variables_added_to_assigns

   log_processing
   send(method, *arguments) #这一步调用perform_action方法，并且传入arguments数组作为参数（虽然perform_action不需要参数）

   assign_default_content_type_and_charset

   response.request = request
   response.prepare! unless component_request?
   response
 ensure
   process_cleanup
 end

step 1:
初始化视图模板类

java 代码

def initialize_template_class(response)
  raise "You must assign a template class through ActionController.template_class= before processing a request" unless @@template_class

  response.template = ActionView::Base.new(view_paths, {}, self) #注意，ActionView这个时候出现了，传入本controller对应的view模板的路径
  response.template.extend self.class.master_helper_module
  response.redirected_to = nil
  @performed_render = @performed_redirect = false #标记render和redirect事件都没有发生
end

step 2:

ruby 代码

def assign_shortcuts(request, response)
  @_request, @_params, @_cookies = request, request.parameters, request.cookies

  @_response         = response
  @_response.session = request.session

  @_session = @_response.session
  @template = @_response.template
  @assigns  = @_response.template.assigns

  @_headers = @_response.headers
end

step 3:

ruby 代码

def initialize_current_url
  @url = UrlRewriter.new(request, params.clone)
end

step 4:
经过了这一步，就可以通过调用action_name来获得action的名称

ruby 代码

def assign_names
   @action_name = (params['action'] || 'index') #取得当前action的名称，如果没有指定action，则默认action为index
 end

step 5:

ruby 代码

def forget_variables_added_to_assigns
  @variables_added = nil
end

step 6:

ruby 代码

def log_processing
  if logger
    logger.info "\n\nProcessing #{controller_class_name}\##{action_name} (for #{request_origin}) [#{request.method.to_s.upcase}]"
    logger.info "  Session ID: #{@_session.session_id}" if @_session and @_session.respond_to?(:session_id)
    logger.info "  Parameters: #{respond_to?(:filter_parameters) ? filter_parameters(params).inspect : params.inspect}"
  end
end

step 7:

ruby 代码

默认对待一个请求的方式是perform_action
可以看到对待一个action，rails的处理方式是：
1。假设action存在，则执行action代码，如果action代码内没有调用过render方法，就调用render方法
2。如果action不存在，则查找method_missing方法，若方法存在，调用之，如果action代码内没有调用过render方法，就调用render方法
3。如果视图模板存在而且模板是public的，则直接调用render方法渲染
4。以上都不满足，抛出UnkownAction异常。
      def perform_action
        if self.class.action_methods.include?(action_name)
          send(action_name)
          render unless performed?
        elsif respond_to? :method_missing
          send(:method_missing, action_name)
          render unless performed?
        elsif template_exists? && template_public?
          render
        else
          raise UnknownAction, "No action responded to #{action_name}", caller
        end
      end

      def action_methods
        self.class.action_methods
      end

      def self.action_methods
        @action_methods ||= Set.new(public_instance_methods - hidden_actions)
      end

step 8:

ruby 代码

step 8:
      def assign_default_content_type_and_charset
        response.content_type ||= Mime::HTML
        response.charset      ||= self.class.default_charset unless sending_file?
      end

最后，一个process完成后返回一个response

由这个process过程引出的，顺便简单看一下render方法
      def render(options = nil, &block) #:doc:
        raise DoubleRenderError, "Can only render or redirect once per action" if performed?

    #可以看出来，在响应action的过程中，如果没有在action中使用过render方法，实际上每次默认都是调用render_for_file方法
    #参数中使用default_template_name方法获得与当前action同名的视图模板的相对路径
        if options.nil?
          return render_for_file(default_template_name, nil, true)
        else
    #render的参数只能是:update或者一个hash
          if options == :update
            options = { :update => true }
          elsif !options.is_a?(Hash)
            raise RenderError, "You called render with invalid options : #{options}"
          end
        end

        if content_type = options[:content_type]
          response.content_type = content_type.to_s
        end

        if location = options[:location]
          response.headers["Location"] = url_for(location)
        end

    指定不同的渲染方式
        if text = options[:text]
          render_for_text(text, options[:status])

        else
          if file = options[:file]
            render_for_file(file, options[:status], options[:use_full_path], options[:locals] || {})

          elsif template = options[:template]
            render_for_file(template, options[:status], true)

          elsif inline = options[:inline]
            add_variables_to_assigns
            render_for_text(@template.render_template(options[:type] || :erb, inline, nil, options[:locals] || {}), options[:status])

    #当在action中显式调用render方式时会执行到此分支
          elsif action_name = options[:action]
            template = default_template_name(action_name.to_s)
    #根据:layout来决定调用那个方法
            if options[:layout] && !template_exempt_from_layout?(template)
              render_with_a_layout(:file => template, :status => options[:status], :use_full_path => true, :layout => true)
            else
              render_with_no_layout(:file => template, :status => options[:status], :use_full_path => true)
            end

          elsif xml = options[:xml]
            response.content_type = Mime::XML
            render_for_text(xml.respond_to?(:to_xml) ? xml.to_xml : xml, options[:status])

          elsif json = options[:json]
            json = "#{options[:callback]}(#{json})" unless options[:callback].blank?
            response.content_type = Mime::JSON
            render_for_text(json, options[:status])

          elsif partial = options[:partial]
            partial = default_template_name if partial == true
            add_variables_to_assigns

            if collection = options[:collection]
              render_for_text(
                @template.send(:render_partial_collection, partial, collection,
                options[:spacer_template], options[:locals]), options[:status]
              )
            else
              render_for_text(
                @template.send(:render_partial, partial,
                ActionView::Base::ObjectWrapper.new(options[:object]), options[:locals]), options[:status]
              )
            end

          elsif options[:update]
            add_variables_to_assigns
            @template.send :evaluate_assigns

            generator = ActionView::Helpers::PrototypeHelper::JavaScriptGenerator.new(@template, &block)
            response.content_type = Mime::JS
            render_for_text(generator.to_s)

          elsif options[:nothing]
            # Safari doesn't pass the headers of the return if the response is zero length
            render_for_text(" ", options[:status])

          else
            render_for_file(default_template_name, options[:status], true)
          end
        end
      end

评论

1 楼 lnj888 2010-05-27  

学习了 谢谢哈
ppt converter