Custom _id values in MongoDB - Mini Project: Build & Apply

Custom _id values in MongoDB

📖 Scenario: You are managing a small library database. Each book needs a unique identifier that you assign yourself instead of letting MongoDB create one automatically.

🎯 Goal: Create a MongoDB collection with books where each book has a custom _id value. Insert multiple books with your chosen _id values.

📋 What You'll Learn

Create a collection named books

Insert documents with a custom _id field

Each document must have _id, title, and author fields

Use string values for the custom _id fields

💡 Why This Matters

🌍 Real World

Custom _id values are useful when you want to control the unique identifiers in your database, such as using ISBNs for books or employee IDs.

💼 Career

Many jobs require managing databases where custom IDs help integrate with other systems or maintain meaningful keys.

1

Create the books collection with one book

Create a collection called books and insert one document with _id set to "book1", title set to "The Great Gatsby", and author set to "F. Scott Fitzgerald".

MongoDB

// Insert one book document with custom _id
// Your code here

Need a hint?

Use db.books.insertOne() with a document that includes _id, title, and author.

2

Add a variable for the second book's _id

Create a variable called secondBookId and set it to the string "book2".

MongoDB

db.books.insertOne({_id: "book1", title: "The Great Gatsby", author: "F. Scott Fitzgerald"})
// Create variable secondBookId
// Your code here

Need a hint?

Use const secondBookId = "book2" to store the custom ID for the next book.

3

Insert the second book using the secondBookId variable

Insert a new document into the books collection with _id set to the variable secondBookId, title set to "1984", and author set to "George Orwell".

MongoDB

db.books.insertOne({_id: "book1", title: "The Great Gatsby", author: "F. Scott Fitzgerald"})
const secondBookId = "book2"
// Insert second book using secondBookId
// Your code here

Need a hint?

Use db.books.insertOne() with _id: secondBookId and the other fields.

4

Insert a third book with a custom _id directly

Insert a third document into the books collection with _id set to "book3", title set to "To Kill a Mockingbird", and author set to "Harper Lee".

MongoDB

db.books.insertOne({_id: "book1", title: "The Great Gatsby", author: "F. Scott Fitzgerald"})
const secondBookId = "book2"
db.books.insertOne({_id: secondBookId, title: "1984", author: "George Orwell"})
// Insert third book with _id "book3"
// Your code here

Need a hint?

Use db.books.insertOne() with the specified fields and _id value.