MongoDB 3 array query operations are very helpful and simplify digging in nested structures. In this post we’ll show how to create queries that match array elements in various ways.
Test collection with book authors
Let’s use the following collection with authors stored in arrays:
db.books.find().pretty()
{ "_id" : 1, "authors" : [ "Joyce", "Dante" ] }
{ "_id" : 2, "authors" : [ "Tolstoy", "Joyce" ] }
{ "_id" : 3, "authors" : [ "Dante", "Joyce" ] }
Documents with only these authors in the same order (the same array)
Console version
db.books.find({authors: ["Joyce", "Dante"]})
{ "_id" : 1, "authors" : [ "Joyce", "Dante" ] }
Java version
// this code is uncool, but works:
BsonArray values = new BsonArray();
values.add(new BsonString("Joyce"));
values.add(new BsonString("Dante"));
books.find(Filters.eq("authors", values));
Any document with Joyce among authors
Console version
db.books.find({authors: "Joyce"})
{ "_id" : 1, "authors" : [ "Joyce", "Dante" ] }
{ "_id" : 2, "authors" : [ "Tolstoy", "Joyce" ] }
{ "_id" : 3, "authors" : [ "Dante", "Joyce" ] }
Java version
books.find(Filters.eq("authors", "Joyce"))
Any document with these two authors in any order in the array
Console version
db.books.find({authors: {$all: ["Joyce", "Dante"]}})
{ "_id" : 1, "authors" : [ "Joyce", "Dante" ] }
{ "_id" : 3, "authors" : [ "Dante", "Joyce" ] }
Java version
// all(field name, value1, value2, ...)
books.find(Filters.all("authors", "Joyce", "Dante"));
Find on specific position in an array:
Console version
db.books.find({"authors.0": "Joyce"}) // 1
{ "_id" : 1, "authors" : [ "Joyce", "Dante" ] }
db.books.find({"authors.1": "Joyce"}) // 2, 3
{ "_id" : 2, "authors" : [ "Tolstoy", "Joyce" ] }
{ "_id" : 3, "authors" : [ "Dante", "Joyce" ] }
Java version
books.find(Filters.eq("authors.0", "Joyce"));
books.find(Filters.eq("authors.1", "Joyce"));
