Dot notation for embedded documents in MongoDB - Mini Project: Build & Apply

Dot notation for embedded documents

📖 Scenario: You are managing a small library database. Each book has a title and an embedded document for the author details, including the author's name and birth year.

🎯 Goal: You will create a collection of books with embedded author documents. Then, you will write queries using dot notation to access the author's name and birth year.

📋 What You'll Learn

Create a collection called books with three documents.

Each document must have a title field and an embedded author document with name and birthYear fields.

Create a variable called authorNameField that stores the string for accessing the author's name using dot notation.

Write a query that finds all books and projects only the title and the author's name using the authorNameField variable.

Write a query that finds all books and projects only the title and the author's birth year using dot notation directly.

💡 Why This Matters

🌍 Real World

Embedded documents are common in MongoDB to store related data together, like author details inside a book document.

💼 Career

Understanding dot notation helps you query and manipulate nested data efficiently in NoSQL databases like MongoDB, a valuable skill for backend and database developers.

1

Create the books collection with embedded author documents

Create a variable called books and assign it an array of three documents. Each document should have a title string and an author embedded document with name and birthYear fields exactly as follows: { title: "Book One", author: { name: "Alice", birthYear: 1970 } }, { title: "Book Two", author: { name: "Bob", birthYear: 1980 } }, and { title: "Book Three", author: { name: "Charlie", birthYear: 1990 } }.

MongoDB

# Create the books array with embedded author documents
# Your code here

Need a hint?

Use an array of objects. Each object has a title and an author object with name and birthYear.

2

Create a variable for the author's name field using dot notation

Create a variable called authorNameField and assign it the string "author.name" to represent the dot notation path to the author's name.

MongoDB

books = [
    { title: "Book One", author: { name: "Alice", birthYear: 1970 } },
    { title: "Book Two", author: { name: "Bob", birthYear: 1980 } },
    { title: "Book Three", author: { name: "Charlie", birthYear: 1990 } }
]
# Create authorNameField variable with string "author.name"
# Your code here

Need a hint?

Assign the string "author.name" to the variable authorNameField.

3

Write a query to find all books projecting title and author's name using the variable

Write a query called queryAuthorNames that uses books.find() with an empty filter {} and a projection object that includes title: 1 and uses the authorNameField variable as a key with value 1 to project the author's name.

MongoDB

books = [
    { title: "Book One", author: { name: "Alice", birthYear: 1970 } },
    { title: "Book Two", author: { name: "Bob", birthYear: 1980 } },
    { title: "Book Three", author: { name: "Charlie", birthYear: 1990 } }
]
authorNameField = "author.name"
# Write queryAuthorNames using books.find with projection of title and authorNameField
# Your code here

Need a hint?

Use bracket notation [authorNameField] to use the variable as a key in the projection object.

4

Write a query to find all books projecting title and author's birth year using dot notation

Write a query called queryAuthorBirthYears that uses books.find() with an empty filter {} and a projection object that includes title: 1 and "author.birthYear": 1 to project the author's birth year using dot notation directly.

MongoDB

books = [
    { title: "Book One", author: { name: "Alice", birthYear: 1970 } },
    { title: "Book Two", author: { name: "Bob", birthYear: 1980 } },
    { title: "Book Three", author: { name: "Charlie", birthYear: 1990 } }
]
authorNameField = "author.name"
queryAuthorNames = books.find({}, { title: 1, [authorNameField]: 1 })
# Write queryAuthorBirthYears using books.find with projection of title and "author.birthYear"
# Your code here

Need a hint?

Use the string "author.birthYear" directly as a key in the projection object.