我要创建api，从那里手动找到学生成绩并比较成绩
我有两个集合student和subject都与参考ID相关联
这是我的app.js
app.js
var express = require('express');
var mongoose = require('mongoose');
var app = express();
var school = require('./controllers/school_controller');
var port = 3000;
var http = require('http');
mongoose.connect(
'mongodb://localhost:27017/company-info',
{useNewUrlParser: true},
err => {
if(err) throw err;
console.log('connection successfully');
}
)
app.set('secreteKey', 'company-info');
app.use(cors({ maxAge: 600 }));
app.use(express.json());
app.use(express.urlencoded({extended: true}));
app.use('/school', school);
http.createServer(app).listen(port, function(req, res){
console.log('start your server on: ', port);
});
这是我的模特
models/school.js
const mongoose = require('mongoose');
const uniqueValidator = require('mongoose-unique-validator');
const bcrypt = require('bcrypt');
const saltRounds = 10;
const mongooseHidden = require('mongoose-hidden')()
var validateEmail = function(email) {
var re = /^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/;
return re.test(email)
};
var adminSchema = new mongoose.Schema({
name: { type: String, required: "name is require"},
mobile_no: { type: String, minlength: 10, maxlength: 14, required: "mobile_no is require"},
user_type: { type: String},
email: {
type: String,
required: 'email is require',
lowercase: true,
unique: true,
validate: [validateEmail, 'Please fill a valid email address']
},
password: {
type: String,
required: true,
hide: true
}
});
adminSchema.pre('save',function(next){
this.password = bcrypt.hashSync(this.password, saltRounds);
next();
});
adminSchema.plugin(mongooseHidden);
adminSchema.plugin(uniqueValidator);
var admin = mongoose.model("admin", adminSchema);
var principleSchema = new mongoose.Schema({
name: { type: String, required: "name is require"},
mobile_no: { type: String, minlength: 10, maxlength: 14, required: "mobile_no is require"},
degree: { type: String, required: "degree is require"},
user_type: { type: String, required: true },
email: {
type: String,
required: true,
lowercase: true,
unique: true,
validate: [validateEmail, 'Please fill a valid email address']
},
password: {
type: String,
required: true,
hide: true
}
});
principleSchema.pre('save',function(next){
this.password = bcrypt.hashSync(this.password, saltRounds);
next();
});
principleSchema.plugin(mongooseHidden);
principleSchema.plugin(uniqueValidator);
var principle = mongoose.model("principle", principleSchema);
var teacherSchema = new mongoose.Schema({
// _id: mongoose.Schema.Types.ObjectId,
name: { type: String, required: "name is require"},
mobile_no: { type: String, minlength: 10, maxlength: 14, required: "mobile_no is require"},
class: { type: Number, required: "class is require" },
user_type: { type: String },
degree: { type: String, required: "degree is require" },
email: {
type: String,
required: 'email is require',
lowercase: true,
unique: true,
validate: [validateEmail, 'Please fill a valid email address']
},
password: {
type: String,
required: true,
hide: true
}
});
teacherSchema.pre('save',function(next){
this.password = bcrypt.hashSync(this.password, saltRounds);
next();
});
teacherSchema.plugin(mongooseHidden);
teacherSchema.plugin(uniqueValidator);
var teacher = mongoose.model("teacher", teacherSchema);
var studentSchema = new mongoose.Schema({
name: { type: String, required: "name is require"},
roll_no: {type: Number, required: "roll_no is require"},
class: { type: Number, require: "class is require"},
user_type: { type: String },
email: {
type: String,
required: 'email is require',
lowercase: true,
unique: true,
validate: [validateEmail, 'Please fill a valid email address']
},
password: {
type: String,
required: true,
hide: true
}
});
studentSchema.pre('save',function(next){
this.password = bcrypt.hashSync(this.password, saltRounds);
next();
});
studentSchema.plugin(mongooseHidden);
studentSchema.plugin(uniqueValidator);
var student = mongoose.model("student", studentSchema);
var subjectSchema = new mongoose.Schema({
result: [{ subject: String, marks: Number }],
student_id: { type: mongoose.Schema.Types.ObjectId, ref: 'student'}
});
subjectSchema.plugin(mongooseHidden, { hidden: { student_id: true}});
var subject = mongoose.model("subject", subjectSchema);
module.exports = { admin: admin, principle: principle, teacher: teacher, student: student, subject: subject }
这是我的控制者：
controllers/school_controller.js
var express = require('express');
var router = express.Router();
var school = require('../models/school');
router.get('/subject_pass', function(req, res){
school.student.find({ class: req.body.class}, async function(err, data){
if(err){
res.send(err);
} else {
// res.send(data);
// console.log(data);
for(var i = 0; i <= 4; i++){
// console.log(data[i]._id);
await school.subject.find({ student_id: data[0]._id}, async function(err, info) {
if (err) {
res.send(err);
} else {
console.log(info);
for(var k = 0; k <= 2; k++){
console.log(info[i].result[k].subject)
console.log(info[i].result[k].marks)
}
await school.subject.aggregate([{ $match: { subject: req.body.subject }}], function(err, details){
if(err){
res.send(err);
} else {
console.log(details);
}
})
}
});
}
}
})
})
module.exports = router;
我正在尝试很多方法，但是我的for(var i = 0; i <= 4; i++)无法正常工作，这会产生错误。
答案 0 :(得分：0)
无论何时使用school.student.find({ class: req.body.class}, ...)搜索主题，它都会在student变量中返回info文档。
根据映射，信息应包含> = 0个条目，因此索引将从0开始，例如：
info[0]，info[1]等
但在代码中
for(var k = 0; k <= 2; k++){
console.log(info[i].result[k].subject)
console.log(info[i].result[k].marks)
}
i是0到4。因此，假设您位于i的最后一个i=3处。但是info变量MAY或MAY不能包含4th元素。
这就是为什么info[i]索引中没有元素时3rd抛出未定义的原因。
基本上，如果您的主题仅包含1个主题，则可以使用0代替i。
for(var k = 0; k <= 2; k++){
console.log(info[0].result[k].subject);
console.log(info[0].result[k].marks);
}
或者如果有多个info，
info.forEach((infoElement)=>{
for(var k = 0; k <= 2; k++){
console.log(infoElement.result[k].subject);
console.log(infoElement.result[k].marks);
}
});