Mongoose: deep population (populate a populated field)

Question

I have Category model:

Category:
    ...
    articles: [{type:ObjectId, ref:\'Article\'}]

Article model contains ref to

Answer 1

Firstly, update mongoose 3 to 4 & then use the simplest way for deep population in mongoose as below :

Suppose you have Blog schema having userId as ref Id & then in User you have some review as ref Id for schema Review. So Basically, you have three schema : 1. Blog 2. User 3. Review

And, you have to query from blog, which user owns this blog & the user review. So you can query your result as :

BlogModel
  .find({})
  .populate({
    path : 'userId',
    populate : {
      path : 'reviewId'
    }
  })
  .exec(function (err, res) {

  })