Document Model

MongoDB documents are displayed in JSON format, but stored in BSON.

Compared to JSON, BSON supports additional data types, like dates, numbers of various types and ObjectIds.

{
  "_id": 1,
  "name": "AC3 Phone",
  "colors": ["black", "silver"],
  "price": 200,
  "available": true
}

ObjectId is a data type used to create unique identifiers for the required _id field.

Every document requires an id field, which acts as a primary key. If an inserted document doesn't include the _id field, MongoDB automatically generates an ObjectId for the _id field.

{
  "_id": ObjectId("5c8eccc1caa187d17ca6ed16"),
  "name": "chair",
  "price": 25.00
}

Data Modeling

Data that is accessed together should be stored together.

Structure your data to match the ways that your application queries and updates it.

Types of Data Relationships

• One-to-one

    {
      "_id": ObjectId("573a1390f29313caabcd413b"),
      "title": "Star Wars: Episode IV - A New Hope",
      "director": "George Lucas",
      "runtime": 121
    }
  

• One-to-many

    {
      "_id": ObjectId("573a1390f29313caabcd413b"),
      "title": "Star Wars: Episode IV - A New Hope",
      "cast": [
        {"actor": "Mark Hamill", "character": "Luke Skywalker"},
        {"actor": "Harrison Ford", "character": "Han Solo"},
        {"actor": "Carrie Fisher", "character": "Princess Leia Organa"}
      ]
    }
  

• Many-to-many

Ways to Model Relationships

• Embedding

    {
      "_id": ObjectId("573a1390f29313caabcd413b"),
      "title": "Star Wars: Episode IV - A New Hope",
      "cast": [
        {"actor": "Mark Hamill", "character": "Luke Skywalker"},
        {"actor": "Harrison Ford", "character": "Han Solo"},
        {"actor": "Carrie Fisher", "character": "Princess Leia Organa"}
      ]
    }
  

• Referencing (Using reference is called linking or data normalization)

    {
      "_id": ObjectId("573a1390f29313caabcd413b"),
      "title": "Star Wars: Episode IV - A New Hope",
      "director": "George Lucas",
      "runtime": 121,
      "filming_locations": [
        ObjectId("654a1420f29313fggbcd718"),
        ObjectId("654a1420f29313fggbcd719")
      ]
    }
  

Pro's and Con's of Embedding vs. Referencing

Drivers

When we run a Node.js application that connects to MongoDB, the application requires a set of libraries to interact with our MongoDB instance. These libraries are referred to as drivers. MongoDB provides a Node.js driver for asynchronous application code.