MongoDB多表关联查询操作实例详解

var mongoose = require('mongoose');
var Schema = mongoose.Schema;
/*定义数据模式*/
var StudentSchema = new mongoose.Schema({
  name: String,
  calssId: {
    type: Schema.Types.objectId,
    ref: 'class'
  },
  age: Number,
  number: Number,
  meta: {
    createAt: {
      type: Date,
      default: Date.now()
    },
    updateAt: {
      type: Date,
      default: Date.now()
    }
  }
  /*更新时间的*/
});
module.exports = StudentSchema;

var mongoose = require('mongoose');
var Schema = mongoose.Schema;
/*定义数据模式*/
var ClassSchema = new mongoose.Schema({
  name: String,
  meta: {
    createAt: {
      type: Date,
      default: Date.now()
    },
    updateAt: {
      type: Date,
      default: Date.now()
    }
  }
  /*更新时间的*/
});
module.exports = ClassSchema;

var mongoose = require('mongoose');
var StudentSchema = require('../schemas/student');
/*通过model编译模式为模型*/
var Student = mongoose.model('student', StudentSchema);
/*导出Student模型 模块*/
module.exports = Student;

var mongoose = require('mongoose');
var ClassSchema = require('../schemas/class');
/*通过model编译模式为模型*/
var Class = mongoose.model('class', ClassSchema);
/*导出Class模型 模块*/
module.exports = Class;

StudentSchema.static = {
  fetch: function(cb){
 return this
   .find({})
   .sort('meta.updateAt') //按更新的时间排序
  }
}

StudentSchema.static('fetch', function(cb){
   return this
     .find({}, cb)
  .sort('meta.updateAt')
})

StudentSchema.static = {
  findStudentWithClass: function (cb) {
    return this
      .find({})
      .populate('classId')//注意这是联合查询的关键
      .sort('meta.updateAt')
      .exec(cb)
  }
}

var Schema = new mongoose.Schema({
  field: {
 type: mongoose.Schema.Type.ObjectId,
 ref: 'model'
  }
});
Schema.static = {
  fetch: function(cb){
 return this
    .find({})
    .populate('field')
    .exec(cb)
 }
 }
var Model = mongoose.Model('model',Schema );