我要做的是首先从学生集中收集所有特定年级和班级的学生。然后使用该请求的年级和班级中的学生ID,使用猫鼬
从Marks集合中使用这些学生ID查找标记。这是我的学生模式
const StudentSchema = new Schema({
base_no:{
type: String,
required: true
},
grade: {
type: Number,
required: false
},
class: {
type: String,
required: false
}
});
const Student = module.exports = mongoose.model('student',StudentSchema,'student');
然后我在学生模型中有一个这样的方法,可以让所有处于特定年级和特定班级的学生获得
/**
* Get all students of a class for a given grade
*
*/
module.exports.getStudentsGradeClass = function(params,callback){
Student.find({grade: params.grade, class: params.class},'base_no first_name last_name').sort({base_no: 1}).exec(callback);
}
这是我的标记架构
const MarksSchema = new Schema({
verifire: {
type: String,
required: true,
//index:true
},
student_base_id: { // as student auto gen key/index no
type: String,
required: true,
//index:true
},
subject_id: {
type: String,
required: true,
ref: 'subject',
//index:true
},
total: {
type: Number,
required: true
}
});
const Marks = module.exports = mongoose.model('school_marks', MarksSchema, 'school_marks');
所以我正在使用以上学生模式的 getStudentsGradeClass() 从客户端获取请求的学生的方法 然后使用此代码使用getStudentsGradeClass()方法中的Student ID从Marks模式中获得分数
/**
* Get marks of all students of the requested grade->class with subject_id
*
*/
module.exports.getClassResults = function (params, callback) {
let marks = [];
Student.getStudentsGradeClass({ grade: params.grade, class: params.class }, (err, students) => {
if (!err) {
for (let i = 0; i < students.length; i++) {
Marks.find({ subject_id: params.subject_id, student_base_id: students[i].base_no }, 'student_base_id total', (err, data) => {
if (!err) {
marks.push(data[0]);
} else {
callback(err, null);
}
});
}
callback(null,marks); // this is the function I wan to invoke
// right after the for loop finishes so
// that i can get all marks of all
//students for a specific subject..
// currently it is undefined(marks[]) coz it goes straight for the callback
// giving control to the for loop, the for loop gives data much later so that
// marks are not pushed to the array when I call it.
} else {
callback(err, null);
}
});
}
所以我可以这样做吗(我知道我身处厄运金字塔中)。请为我建议一种更清洁的方法,或者您可以指导我克服此问题或如何实现我想要达到的目标。非常感谢您的帮助。
答案 0 :(得分:1)
您可以尝试使用异步/等待...........
module.exports.getClassResults = (params, callback)=> {
let marks = [];
Student.getStudentsGradeClass({ grade: params.grade, class: params.class },async (err, students) => {
if (!err) {
for (let student of students){
let data=await Marks.find({ subject_id: params.subject_id, student_base_id: student.base_no }, 'student_base_id total')
if (data) {
marks.push(data[0]);
} else {
callback(err, null);
}
}
callback(null,marks); // this is the function I wan to invoke
// right after the for loop finishes so
// that i can get all marks of all
//students for a specific subject..
// currently it is undefined(marks[]) coz it goes straight for the callback
// giving control to the for loop, the for loop gives data much later so that
// marks are not pushed to the array when I call it.
} else {
callback(err, null);
}
});
}