MongoDB - Query an Array of Embedded Documents

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In this MongoDB tutorial we will learn to query an array of embedded documents.

Login to your MongoDB server and insert the following documents.

For this tutorial I will insert the documents in the books collection.

> db.books.insertMany([
  {
    "title": "The C Programming Language",
    "author": ["Brian Kernighan", "Dennis Ritchie"],
    "inventory": [
      { "warehouse": "W1", "qty": 3000 },
      { "warehouse": "W2", "qty": 750 }
    ]
  },
  {
    "title": "MongoDB in Action",
    "author": ["Kyle Banker"],
    "inventory": [
      { "warehouse": "W2", "qty": 100 },
      { "warehouse": "W3", "qty": 1500 }
    ]
  },
  {
    "title": "Node.js in Action",
    "author": ["Marc Harter", "Nathan Rajlich", "T. J. Holowaychuk", "Mike Cantelon"],
    "inventory": [
      { "warehouse": "W1", "qty": 100 },
      { "warehouse": "W3", "qty": 250 }
    ]
  }

]);

Select based on exact match of embedded document in an array

In the following example we are fetching all the documents having the exact embedded document { "warehouse": "W1", "qty": 100 } in the inventory array.

Note! The field order is important i.e. the first field of the embedded document must be "warehouse" and must have value "W1" and the second field of the embedded document must be "qty" and must have value 100.

> db.books.find({ "inventory": { "warehouse": "W1", "qty": 100 } }).pretty();



{
  "_id" : ObjectId("5d2d9afd81a3cd0a9239c121"),
  "title" : "Node.js in Action",
  "author" : [
    "Marc Harter",
    "Nathan Rajlich",
    "T. J. Holowaychuk",
    "Mike Cantelon"
  ],
  "inventory" : [
    {
      "warehouse" : "W1",
      "qty" : 100
    },
    {
      "warehouse" : "W3",
      "qty" : 250
    }
  ]
}

If we change the field order of the embedded document in the query then we will not get the result.

In the following query we are changing the field order of the embedded document to { "qty": 100, "warehouse": "W1" } and it gives us no result.

> db.books.find({ "inventory": { "qty": 100, "warehouse": "W1" } }).pretty();

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