#connect
library(rmongodb)
mongo <- mongo.create(host = '主机',
                      username = '用户名',
                      password = '密码',
                      db = 'media')
mongo.is.connected(mongo)
mongo.get.database.collections(mongo,db = 'media')

mongo.count(mongo,ns = 'tablename')
#-------------------------------------------------------------------------------
# get data
#----------------------------------------------------------------------------------
startDate <- as.POSIXct("2016-12-18 16:00:00",tz='GMT')
endDate <- as.POSIXct("2016-12-25 16:00:00",tz='GMT')
q <- mongo.bson.from.list(list("date" = list("$gte" = startDate,"$lte" = endDate)))
list <- mongo.find.all(mongo,ns = 'tablename',q,fields = '{"wechat_id":1,"gzh_name":1,"title":1,"url":1,"read_num":1,"like_num":1,"date":1,"updated_at":1,"created_at":1}')
#创建dataframe
df <- data.frame( wechat_id = NA,
                  gzh_name = NA,
                  title = NA,
                  url = NA,
                  read_num = NA,
                  like_num = NA,
                  date = NA,
                  updated_at = NA,
                  created_at = NA
                  
                  
)