目前最常用的方法是利用Unix自身的cron功能来实现定时任务，但是cron的语法比较麻烦(个人感觉)，今天为了执行一个定时任务发现了一个很好的RubyGem可以让你用Ruby的方式定义定时任务，这就是Whenever。
Whenever可以让你写出类似下面的定时任务：
set :cron_log, "/path/to/my/cron_log.log" every 2.hours do command "/usr/bin/some_great_command" runner "MyModel.some_method" rake "some:great:rake:task" end
赶快去Github看看文档和代码吧http://github.com/javan/whenever
There are a number of ways of parsing an RSS feed in Ruby, but one of the best is a gem called Feedzirra. The main advantage of Feedzirra is its speed; it parses feeds very quickly, but it is also useful as it can parse many different types of feed.
To install Feedzirra we first need to make sure that
1 | http://gems.github.com |
is in our list of gem sources. If not we’ll need to add it.
gem sources -a http://gems.github.com
Now we can install the gem:
sudo gem install pauldix-feedzirra
Notice: When I was installing the gem, there are several libs needed, including libcurl4-gnutls-dev libcurl3-gnutls libxslt1-dev, you may not meet this issue, it’s not a big deal, just install what it rely on. Several dependencies will also be installed alongside the gem. Once everything’s installed we’ll need to add a reference to the gem in our application’s /config/environment.rb file.
config.gem "pauldix-feedzirra", :lib => "feedzirra", :source => "http://gems.github.com"
That’s it. We’re ready to start parsing RSS feeds in our application.
Getting start:
Assume that, you’ve got a model to store the feed content which is fetched by the parser, so the model should be like :
class FeedEntry < ActiveRecord::Base
def self.update_from_feed(feed_url)
feed = Feedzirra::Feed.fetch_and_parse(feed_url)
add_entries(feed.entries)
end
private
def self.add_entries(entries)
entries.each do |entry|
unless exists? :guid => entry.id
create!(
:name => entry.title,
:summary => entry.summary,
:url => entry.url,
:published_at => entry.published,
:guid => entry.id
)
end
end
end
end
A more detailed manual is here!
I found a cool gem called “cheat”, it’s pretty handy and convenient when you wanna see a brief help/introduction of some “stuff” in command line, cheat out the website for more wiki-versioned cheat sheet.
Get started:
$ sudo gem install cheat
$ cheat strftimeA magnificent cheat sheet for Ruby’s strftime method will be printed to your terminal.
To get some help on cheat itself:
$ cheat cheatHow meta.
Cheat sheets are basically wiki pages accessible from the command line. You can browse, add, or edit cheat sheets. Try to keep them concise. For a style guide, check out the cheat cheat sheet.
To access a cheat sheet, simply pass the program the desired sheet’s name:
$ cheat
Reference : CLICK HERE!
Quote from Gary’s weekly code review post, thanks to Gary Zhang.
all advises on Ruby on Rails code:
* Lesson 1. Move code from Controller to Model
1. Move finder to named_scope
2. Use model association
3. Use scope access
4. Add model virtual attribute
5. Use model callback
6. Replace Complex Creation with Factory Method
7. Move Model Logic into the Model
8. model.collection_model_ids (many-to-many)
9. Nested Model Forms (one-to-one)
10. Nested Model Forms (one-to-many)* Lesson 2. RESTful Conventions
1. Overuse route customizations
2. Needless deep nesting
3. Not use default route* Lesson 3. Model
1. Keep Finders on Their Own Model
2. Love named_scope # same as Move finder to named_scope
3. the Law of Demeter
4. DRY: metaprogramming
5. Extract into Module
6. Extract to composed class
7. Use Observer* Lesson 4. Migration
1. Isolating Seed Data
2. Always add DB index* Lesson 5. Controller
1. Use before_filter
2. DRY Controller* Lesson 6. View
1. Move code into controller
2. Move code into model
3. Move code into helper
4. Replace instance variable with local variable
5. Use Form Builder
6. Organize Helper filesI think all these advises are very useful for our farther refactor on our system.
There is a very cool gem to check code according these advises(Sources : Rails Best Practices)
install:
sudo gem install rails_best_practices –source http://gemcutter.orgusage:
in rails rails app, run “rails_best_practices .” (don’t forget the parameter: “.”)
Not try this tool yet, but it looks really handy.
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