诗歌rails之如何写一个简单的Rails Plugin

生成plugin骨架代码:

ruby script\generate plugin MyPlugin

ruby script\generate plugin MyPlugin

功能需求:
在BlogController中把所有符合条件的Post(Model)生成为xml
如果不使用插件,很easy :
in BlogController

def export_to_xml
posts = Post.find(:all, :order => 'published_date',
:conditions => ['title = ?', 'love'])
send_data posts.to_xml, :type => 'text/xml; charset=UTF-8;',
:disposition => "attachment; filename=posts.xml"
end

def export_to_xmlposts = Post.find(:all, :order => 'published_date',:conditions => ['title = ?', 'love'])send_data posts.to_xml, :type => 'text/xml; charset=UTF-8;',:disposition => "attachment; filename=posts.xml"
end

如果使用插件,我们要求能这样:

class BlogController < ApplicationController
my_plugin :post

def to_xml
export_to_xml
end
end

class BlogController < ApplicationControllermy_plugin :postdef to_xmlexport_to_xmlend
end

OK,立刻满足以上的要求,进入你的project:
生成plugin

ruby script\generate plugin MyPlugin

ruby script\generate plugin MyPlugin

and than to find:
vendor/plugins/my_plugin/lib/my_plugin.rb
接着就是edit了:

module MyPlugin

def self.included(base)
base.extend(ClassMethods)
end

class Config
attr_reader :model
attr_reader :model_id

def initialize(model_id)
@model_id = model_id
@model = model_id.to_s.camelize.constantize
end

def model_name
@model_id.to_s
end
end

module ClassMethods

def my_plugin(model_id = nil)
model_id = self.to_s.split('::').last.sub(/Controller$/, '').pluralize.singularize.underscore unless model_id
@my_plugin_config = MyPlugin::Config.new(model_id)
include MyPlugin::InstanceMethods
end

def my_plugin_config
@my_plugin_config || self.superclass.instance_variable_get('@my_plugin_config')
end

end

module InstanceMethods

def export_to_xml
data = self.class.my_plugin_config.model.find(:all, :order => 'published_date', :conditions => conditions_for_collection)
send_data data.to_xml, :type => 'text/xml; charset=UTF-8;',
:disposition => "attachment; filename=#{self.class.my_plugin_config.model_name.pluralize}.xml"
end

# 在controller中覆盖此method,写入满足的条件
def conditions_for_collection
end

end

end

module MyPlugindef self.included(base)base.extend(ClassMethods)endclass Configattr_reader :modelattr_reader :model_iddef initialize(model_id)@model_id = model_id@model = model_id.to_s.camelize.constantizeenddef model_name@model_id.to_sendendmodule ClassMethodsdef my_plugin(model_id = nil)model_id = self.to_s.split('::').last.sub(/Controller$/, '').pluralize.singularize.underscore unless model_id@my_plugin_config = MyPlugin::Config.new(model_id)include MyPlugin::InstanceMethodsenddef my_plugin_config@my_plugin_config || self.superclass.instance_variable_get('@my_plugin_config')endendmodule InstanceMethodsdef export_to_xmldata = self.class.my_plugin_config.model.find(:all, :order => 'published_date', :conditions => conditions_for_collection)send_data data.to_xml, :type => 'text/xml; charset=UTF-8;',:disposition => "attachment; filename=#{self.class.my_plugin_config.model_name.pluralize}.xml"end# 在controller中覆盖此method,写入满足的条件def conditions_for_collectionendendend

OK了吗? No No No 还要让rails加载plugin,在rails应用启动时,会到vendor/plugins目录查找所有plugin,并执行其中的init.rb
那么就edit init.rb

ActionController::Base.class_eval do
include MyPlugin
end

ActionController::Base.class_eval doinclude MyPlugin
end

或edit这样:

require 'my_plugin'
ActionController::Base.send :include, MyPlugin

require 'my_plugin'
ActionController::Base.send :include, MyPlugin

最后就按上面的需求写入controller了