MongoDB：根据另一个集合更新一个集合

Question

I've a project of online quiz portal web site. These are my models:

User model

const userSchema = new Schema({
  firstName: { type: String, required: true, maxlength: 15 },
  lastName: { type: String, required: true, maxlength: 15 },
  rank: Number
});

Score model

const scoreSchema = new Schema({
  userId: ObjectId,
  quizId: ObjectId,
  marks: Number,
  answers: [{ type: Object }],
});

I want to update my User model every time after I insert a record to the Score model.

This is unsurprisingly my formula for the rank.

avg = Total marks / Total participated quizzes

How could I achieve this using MongoDB or Mongoose?

Answer 1

You can utilize the mongoose schema method . let see how.

User Schema:

const userSchema = new Schema({
       firstName: { type: String, required: true, maxlength: 15 },
       lastName: { type: String, required: true, maxlength: 15 },
       rank: Number
});

const User = mongoose.model('User', userSchema);

Score Schema:

const scoreSchema = new Schema({
   userId: ObjectId,
   quizId: ObjectId,
   marks: Number,
   answers: [{ type: Object }],
});

// Add post save method on this schema
 scoreSchema.post('save', function (doc) {
   console.log('this fired after a document was saved');
   // doc.userId  is you user for this score so
  // rank:calculated_rank you formula here
   User.updateOne({_id:doc.userId} , {rank:calculated_rank}) 
 });
 // model 
 const Score = mongoose.model('Score', scoreSchema);

So whenever you call save on score schema then post('save') will be fired and you can update userSchema in this function.