Mongoose - Populate Object in Array

Question

Using mongoose how can I populate a single object in an array?

For Example:

var SchoolSchema = new Schema({
  classes: [{
  name: String
  }]
});

var StudentSchema = new Schema({
  allocated_class: {
    type: ObjectId,
    ref: 'School'
  }
});

mongoose.model('School', SchoolSchema);
mongoose.model('Student', StudentSchema);

Student.find({}).populate("allocated_class").exec();

In the above example, how can I populate the name of the one class when finding all students?

Example data:

Student

{
    "allocated_class" : ObjectId("561e36540fc3c18b749d65e1"),
}

School

{
  "_id" : ObjectId("561e36320fc3c18b749d65e0"),
  "classes" : [ 
   {
      "name" : "Class 1",
      "_id" : ObjectId("561e36540fc3c18b749d65e1")
   }]
}

The end result should be the student collection populated with the name of their allocated class.

Answer 1

Try this

var StudentSchema = new Schema({
  name:{type: String, unique: true},
  allocated_class: [schoolSchema]
});

even if not like this - you should make the change in schema. One school has many classes, One student has many classes, so (new) Classes Schema could be the connection between school and student.