这有可能解决一个复杂的猫鼬填充查询吗

Question

我有四个表。#第一个表

var mongoose=require('mongoose');
var Schema=mongoose.Schema;
#First table
var studentSchema=new Schema({
student_name: { type: String, required: true },
sendKey: { type: String },
created_by: { type:String },
updated_at: { type: Date, default: Date.now },
})
module.exports=mongoose.model('Student',studentSchema);

#第二表

var mongoose=require('mongoose');
var Schema=mongoose.Schema;
var institutionSchema=new Schema({
institution_name: { type: String, lowercase: true },
email: { type:String },
created_by: { type:String },
created_at: { type: Date, default: Date.now },
updated_at: { type: Date, default: Date.now },
})
module.exports=mongoose.model('Institution',institutionSchema);

#第三表

var mongoose=require('mongoose');
// var Institution = ('./institution');
var Schema=mongoose.Schema;
var batchSchema=new Schema({
batch_name: { type: String, required: true },
institution: { type: Schema.Types.ObjectId, ref: 'Institution' },
created_by: { type:String },
created_at: { type: Date, default: Date.now },
updated_at: { type: Date, default: Date.now },
})
module.exports=mongoose.model('Batch',batchSchema);

#第四张表

var mongoose=require('mongoose');
var Schema=mongoose.Schema;
var batchtudentSchema=new Schema({
student_id: { type: Schema.Types.ObjectId, ref: 'Student', required : true},
batch_id: { type: Schema.Types.ObjectId, ref: 'Batch', required:true},
created_at: { type: Date, default: Date.now },
updated_at: { type: Date, default: Date.now },
})
module.exports=mongoose.model('BatchStudent',batchtudentSchema);

我有一个机构Id。我想用批次详细信息find该机构的所有学生。我主要试过……那样做。

Student.find().populate('BatchStudent').pupulate('Batch').populate('Institution').exec((err, docs) => {
console.log(docs)
res.json(
{
data:docs
}
)
})

它不起作用。。只发送所有学生数据。。如何正确获取数据？

Answer 1

// Student Schema
var mongoose=require('mongoose');
var Schema=mongoose.Schema;
var studentSchema=new Schema({
student_name: { 
type: String, 
required: true 
},
sendKey: { 
type: String
},
batchStudent: {
type: Schema.Types.ObjectId, 
ref: 'BatchStudent', 
}
created_by: { 
type:String
},
updated_at: {
type: Date, 
default: Date.now
},
})
module.exports=mongoose.model('Student',studentSchema);
// BatchStudent Schema
var mongoose=require('mongoose');
var Schema=mongoose.Schema;
var batchtudentSchema=new Schema({
student_id: {
type: Schema.Types.ObjectId, 
ref: 'Student', 
required : true
},
batch_id: { 
type: Schema.Types.ObjectId, 
ref: 'Batch'
},
institution: {
type: Schema.Types.ObjectId,
ref: 'Institution'
}
})
module.exports=mongoose.model('BatchStudent',batchtudentSchema);
// Institution Schema
var mongoose=require('mongoose');
var Schema=mongoose.Schema;
var institutionSchema=new Schema({
institution_name: { 
type: String, 
lowercase: true
},
email: { 
type: String
},
created_by: { 
type:String 
}
});
module.exports=mongoose.model('Institution',institutionSchema);

如果我删除了created_at和updated_at以避免重复。始终遵守DRY原则(不要重复(

如果你需要获得文件，你可以简单地使用深度人口/协会，如下所示：

Student.find({}).populate({
path : 'batchStudent',
populate : {
path : 'institution'
}
}).exec(function (err, res) {
// do whatever you need to do here
})