Ruby on Rails框架程序连接MongoDB的教程

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