How to get part of a document in mongo?

Question

MongoDB

For example, there is such a document in the authors collection:

{
  "name" : "Andrew Erlichson",
  "books" :  {
                [
                  {
                    "title" : "MongoDb best practice",
                    "name" : "o'Reilly",
                    "year" : "2013"
                  }
                 ]
               }
 }

How to get only the zero element of the books array? how to get the value of the year field?

Answer 1

Found the answer in the video tutorial. Everything is solved easier:
well, or

db.authors.findOne( { name : "Andrew Erlichson" } ).books[0].year

Answer 2

what does null mean? first?
docs.mongodb.org/manual/reference/method/cursor.limit
"how to pull the year field value?"
docs.mongodb.org/manual/reference/method/db.collec...
Have you even read the documentation?

Answer 3

How to get only the zero element of the books array?

Part of an array (or one element) can be accessed using $slice
db.col.find({}, {'books.year': 1}) - so it should return the year field (but over all array elements).
If you don't really need an array, then you can use a dictionary instead with keys 0, 1, 2, 3...
Then the query will be like this: db.col.find({}, {'books.0.year' : one})