Ruby on Rails框架程序连接MongoDB的教程

    前边有介绍mongodb的安装以及ror项目的搭建,现在进行一下整合。

    1.创建项目

    创建项目时不再使用rails active_record支持

    
    rails new todo -O
    

    2.我们将要使用MongoMapper来驱动MongoDB到Rails

    编辑GemFile,增加下面的内容

    
    gem"mongo_mapper"
    

    然后  执行 bundle install 安装gem

    
    bundle install
    

    3.添加数据库链接

    在config/initializer下面新建一个mongo.rb文件,指定全局的数据库信息:

    
    MongoMapper.connection = Mongo::Connection.new('localhost', 27017)
    
    
    MongoMapper.database ='todo'#通过指定Rails运行环境参数,我们可以在不同的运行环境下创建互不干扰的数据,为了简单起见,没有为不同的环境指定不同的数据
    
    
    
    if defined?(PhusionPassenger)
    
      PhusionPassenger.on_event(:starting_worker_process)do|forked|
    
        MongoMapper.connection.connectifforked
    
      end
    
    end
    
    

    完成以上步骤后,启动程序:

    
    $ rails server
    
    
    
    **Notice: C extension not loaded. This is required for optimum MongoDB Ruby driver performance.
    
    You can install the extension as follows:
    
    
    
    gem install bson_ext
    
    
    
    If you continue to receive this message after installing, make sure that the
    
    bson_ext gem is in your load path and that the bson_ext and mongo gems are of the same version.
    
    => Booting WEBrick
    
    => Rails 3.0.10 application starting in development on http://0.0.0.0:3000
    
    => Call with -d to detach
    
    => Ctrl-C to shutdown server
    
    [2011-10-19 23:36:14] INFO WEBrick 1.3.1
    
    [2011-10-19 23:36:14] INFO ruby 1.9.2 (2011-07-09) [x86_64-linux]
    
    [2011-10-19 23:36:14] INFO WEBrick::HTTPServer#start: pid=19595 port=3000
    
    

    从上面输出中可以看到bson_ext库没有加载。按照提示安装该库即可(别忘了在gemfile中添加gem):

    再次启动程序,Notice提示消息消失,启动正常。在浏览器输入:http://127.0.0.1:3000,就可以看到如下页面

    4.添加页面和处理逻辑

    通过rails的generate命令来生成页面、控制器和模型层文件(个人还是喜欢自己手动创建,这里为了演示方便)

    
    rails generate scaffold project name:string --orm=mongo_mapper
    
    

    由于我们使用mongo作为数据库。那么,我们需要把ActiveRecord的model,改成MongoMapper的类型,也就是把继承关系从ActiveRecord::Base变成MongoMapper::Document。我们使用key这个方法标明该MongoMapper的字段属性。我们的属性是name,再加上这个字段的类型String,那么定义如下:

    
    classProject
    
      include MongoMapper::Document
    
      key:name,String
    
    end
    
    

    通过以上的修改,我们就已经拥有了所有添加,更新,删除和列表的操作

    5.数据查看

    可以通过命令mongo进入mongodb数据库进行数据的查询

    
    mongo //进入数据库
    
    use todo //切换库
    
    db.projects.find() //执行查询
    
    
    
    6.其他

    MongoMapper和ActiveRecord是完全相同的。甚至,MongoMapper还是支持ActiveRecord的验证方式如下

    
    validates_presence_of:name
    

    由于MongoDB没有schema-less(数据版本记录)我们可以非常容易的添加和更改model的属性,而不需要执行任何migrations的操作。比如,我们需要添加一个priority的属性,我们仅仅需要的是修改Project model如下:

    
    classProject
    
      include MongoMapper::Document
    
      key:name,String,:required=>true
    
      key:priority,Integer
    
    end
    
    

    表之间的关联对于MongoDB这里稍微有点区别,我们需要ObjectId类型来存储所有id。

    至于,处理不同表之前的关联,我们可以像ActiveRecord一样定义belongs_to,当然,稍微有点不同,在Project中我们需要定义has_many :tasks,在MongoMapper中需要用many代替。

    我目前也就做到这里。有时间再去深入研究其他的功能。

    PS:Ruby编写MongoDB备份脚本(fsync & lock)

    
    #!/usr/local/bin/ruby
    # date:    06-12-2014
    # auther: lucifer
    # use fsync and lock to the file-system before backup the file-system
    # mongo-ruby-driver version > 1.10.0
    
    require 'mongo'
    require 'fileutils'
    require 'date'
    
    include Mongo
    include BSON
    
    # the members of replcation-set
    # test mongodb server version 2.6.0
    # host = "192.168.11.51"
    
    # The port of members
    # If the port is 27017 by default then otherport don't need to assignment
    # otherport = ""
    # port = otherport.length != 0 ? otherport : MongoClient::DEFAULT_PORT
    
    # opts = {:pool_size => 5, :pool_timeout => 10}
    # Create a new connection
    # client = MongoClient.new(host, port, opts)
    
    uri_string = "mongodb://caoqing:xxxxxxxx@x.x.x.x:27017/admin"
    client = MongoClient.from_uri(uri = "#{uri_string}")
    db = client['admin']
    
    # fsync and lock the database
    cmd = OrderedHash.new
    cmd[:fsync] = 1
    cmd[:lock] = true
    # p cmd
    db.command(cmd)
    
    # datafile path
    d = "/var/lib/mongo"
    
    # dir = Dir.new("#{d}")
    # entries = dir.entries
    # entries.delete_if { |entry| entry =~ /^\./}
    # convert the relative path to the full path
    # entries.map! { |entry| File.join(dir.path, entry) }
    # maintain only the type of file
    # entries.delete_if { |entry| !File.file?(entry) }
    # p entries
    
    start = Date.today.to_s
    prev = (Date.today - 7).to_s
    
    dest = "/backup/#{start}"
    sour = "/backup/#{prev}"
    
    FileUtils.rm_rf("#{sour}") if File::exist?("#{sour}")
    
    Dir.mkdir("#{dest}", 0755) unless File::exist?("#{dest}")
    
    FileUtils.cp_r Dir.glob("#{d}/**"), dest if client.locked?
    
    puts "*" * 20
    puts "\tbackup complete"
    puts "*" * 20
    
    # DB::SYSTEM_COMMAND_COLLECTION
    # unlock the database
    db["$cmd.sys.unlock"].find_one
    client.close