Populate mongoose across levels and display certain fields

Question

const userSchema = new Schema({
  name: String,
  email: String,
  friends: [{ type: ObjectId, ref: 'User' }]
});

User.
  findOne({ name: 'Val' }).
  populate({
    path: 'friends',
    populate: { path: 'friends' }
  });

The above schema populates the entire User fields for friends array, but for the friends array, I need only name to be populated. How do I limit the fields in the nested level in mongoose.

Answer 1

Generally speaking, you would first populate friends as you have done and then add select to simply get the fields that you wanted to extract from the User model.

User.findOne({ name: 'Val' })
  .populate({
    path: 'friends',
    select: ['name', 'fieldName']
  })

---

I have added array of elements to demonstrate that you can select more fields that way, in your case it would just be name.