Mongomapper 用户mongo数据库配置，以及其提供了很多mongo的方法，可以很好地用来 对mongo相关封装和操作。
环境准备：gem install mongo_mapper
和activerecord很类似。将mongo的collection（表）和 类一一对应。
mongo_mapper 网上方法资源：http://mongomapper.com/documentation/plugins/querying.html
1、mongo配置从yml文件中读取
mongo55:
host: ***
port: ***
database: ****
2、mongo collection封装：
1）初始化mongo数据库连接
2）将需要的collections name 以类形式封装
#encoding:utf-8
require 'active_model'
require 'mongo'
require 'mongo_mapper'
=begin
author: kanlijun
date: 2016/07/13
description: 使用mongo_mapper模块实现collections封装，统一调配；初始化mongo连接，定义表和类对应关系
=end
class ConnectMongo
def initialize(host,port,database)
MongoMapper.connection =Mongo::Connection.new(host,port)
MongoMapper.database=database
end
end
#mobile
class Mobile
include MongoMapper::Document
set_collection_name 'mobile'
end
#ncontacts
class Ncontact
include MongoMapper::Document
end
3、调用rb文件案例：
1）读取yml配置数据，并初始化；
2）使用mongo_mapper的mongo操作方法
#encoding:utf-8
require 'mongo_mapper'
require_relative '../source/core/mongodb'
DATA_PATH='../source/data/mongo.yml'
mongo = YAML.load(File.open(DATA_PATH))
db =mongo['mongo55']
host,port,database =db['host'],db['port'],db['database']
ConnectMongo.new(host,port,database)
mobile = Mobile.all(:anion=>'789757')
puts mobile[0]['de']
puts mobile.length
#条件搜索排序
nsms = Nsms.where(:urr=>'789757').sort(:time.desc).all
puts nsms[1]['p']
lim =Nsms.first
# puts lim
puts lim['urr']
#排序
mo= Nsms.sort(:time.desc).first
puts mo['urr']
#随机拿出几个
mo= Nsms.limit(3).all
puts mo[0]['urr']
puts mo[2]['urr']
count = Nsms.where(:urr=>'789757').count
puts "count:#{count}"