Mongoose populate - when

Question

I want to populate posts with author name. I created models with references, routes also. When should I populate posts, before saving new post or later, how does it work actually ?

Answer 1

Population is used when querying to replace a stored id in one document with the corresponding document from another collection.

You will need to save the _id of the author document in your post documents:

var post = new Post({
  ...
  author: // id of author doc
  ...
})

post.save()

You would then use populate when retrieving the documents in order to replace the stored author id with the author document itself:

Post
  .find({})
  .populate('author')
  .exec(function (err, posts) {
    if (err) {
      // Handle error
    }

    // Handle results
    posts.forEach(post => {
      // Assuming author documents have a 'name' property
      console.log(post.author.name)
    })
  })

This might also help: http://mongoosejs.com/docs/populate.html