Query filter syntax in MongoDB - Mini Project: Build & Apply

Query Filter Syntax in MongoDB

📖 Scenario: You are managing a small online bookstore database. You want to find books based on certain criteria like author, price, and availability.

🎯 Goal: Build MongoDB queries step-by-step to filter books by author, price, and stock status using query filter syntax.

📋 What You'll Learn

Create a collection named books with sample book documents

Add a filter variable to specify query conditions

Write a MongoDB query using the filter to find matching books

Complete the query with a projection to show only title and author

💡 Why This Matters

🌍 Real World

Filtering data is a common task in databases to find specific records quickly, such as finding books by a certain author or price range.

💼 Career

Understanding query filter syntax is essential for database administrators, backend developers, and data analysts who work with MongoDB or similar NoSQL databases.

1

Create the books collection with sample documents

Create a variable called books and assign it a list of three book documents with these exact fields and values: { title: "The Great Gatsby", author: "F. Scott Fitzgerald", price: 10, inStock: true }, { title: "1984", author: "George Orwell", price: 15, inStock: false }, and { title: "To Kill a Mockingbird", author: "Harper Lee", price: 12, inStock: true }.

MongoDB

# Create the books collection with three book documents
# Your code here

Need a hint?

Use a list of dictionaries to represent the books collection with exact field names and values.

2

Create a filter to find books by author "George Orwell"

Create a variable called filter and assign it a dictionary with the key author and value "George Orwell" to filter books by this author.

MongoDB

books = [
    { "title": "The Great Gatsby", "author": "F. Scott Fitzgerald", "price": 10, "inStock": true },
    { "title": "1984", "author": "George Orwell", "price": 15, "inStock": false },
    { "title": "To Kill a Mockingbird", "author": "Harper Lee", "price": 12, "inStock": true }
]
# Create a filter to find books by author "George Orwell"
# Your code here

Need a hint?

Use a dictionary with the key author and value "George Orwell" to create the filter.

3

Write a MongoDB query using the filter to find matching books

Create a variable called query_result and assign it the result of filtering the books list using the filter variable. Use a list comprehension that checks if each book's author matches the filter's author.

MongoDB

books = [
    { "title": "The Great Gatsby", "author": "F. Scott Fitzgerald", "price": 10, "inStock": true },
    { "title": "1984", "author": "George Orwell", "price": 15, "inStock": false },
    { "title": "To Kill a Mockingbird", "author": "Harper Lee", "price": 12, "inStock": true }
]
filter = { "author": "George Orwell" }
# Use a list comprehension to filter books by author
# Your code here

Need a hint?

Use a list comprehension to select books where the author matches the filter's author.

4

Complete the query with a projection to show only title and author

Create a variable called final_result and assign it a list of dictionaries containing only the title and author fields from each book in query_result. Use a list comprehension to extract these fields.

MongoDB

books = [
    { "title": "The Great Gatsby", "author": "F. Scott Fitzgerald", "price": 10, "inStock": true },
    { "title": "1984", "author": "George Orwell", "price": 15, "inStock": false },
    { "title": "To Kill a Mockingbird", "author": "Harper Lee", "price": 12, "inStock": true }
]
filter = { "author": "George Orwell" }
query_result = [book for book in books if book["author"] == filter["author"]]
# Create a projection to show only title and author
# Your code here

Need a hint?

Use a list comprehension to create a new list with dictionaries containing only title and author from each book.