mongoose populate nedir code example

Example 1: mongoose populate

Story.
  findOne({ title: /casino royale/i }).
  populate('author', 'name'). // only return the Persons name
  exec(function (err, story) {
    if (err) return handleError(err);

    console.log('The author is %s', story.author.name);
    // prints "The author is Ian Fleming"

    console.log('The authors age is %s', story.author.age);
    // prints "The authors age is null'
  });

Example 2: how to use mongoose populate

function getUserWithPosts(username){  return User.findOne({ username: username })    .populate('posts').exec((err, posts) => {      console.log("Populated User " + posts);    })}