$or operator behavior in MongoDB - Mini Project: Build & Apply

$or Operator Behavior in MongoDB Queries

📋 What You'll Learn

💡 Why This Matters

🌍 Real World

Using the $or operator is common when searching databases for records that meet one or more criteria, such as finding products on sale or customers from specific cities.

💼 Career

Understanding how to use $or in MongoDB queries is essential for database developers and data analysts to retrieve flexible and accurate data from NoSQL databases.

1

Create the books collection with sample documents

Create a variable called books and assign it an array with these exact documents: { title: "The Great Gatsby", author: "F. Scott Fitzgerald", price: 10 }, { title: "1984", author: "George Orwell", price: 15 }, { title: "To Kill a Mockingbird", author: "Harper Lee", price: 8 }, { title: "The Catcher in the Rye", author: "J.D. Salinger", price: 12 }.

MongoDB

// Create the books array with the specified documents
// Your code here

Need a hint?

Use an array of objects with the exact titles, authors, and prices given.

2

Define the price limit variable

Create a variable called priceLimit and set it to 12.

MongoDB

const books = [
  { title: "The Great Gatsby", author: "F. Scott Fitzgerald", price: 10 },
  { title: "1984", author: "George Orwell", price: 15 },
  { title: "To Kill a Mockingbird", author: "Harper Lee", price: 8 },
  { title: "The Catcher in the Rye", author: "J.D. Salinger", price: 12 }
];

// Define the priceLimit variable
// Your code here

Need a hint?

Use const priceLimit = 12; to set the price limit.

3

Write the MongoDB query using the $or operator

Create a variable called query and assign it an object with a $or array containing two conditions: { author: "George Orwell" } and { price: { $lt: priceLimit } }.

MongoDB

const books = [
  { title: "The Great Gatsby", author: "F. Scott Fitzgerald", price: 10 },
  { title: "1984", author: "George Orwell", price: 15 },
  { title: "To Kill a Mockingbird", author: "Harper Lee", price: 8 },
  { title: "The Catcher in the Rye", author: "J.D. Salinger", price: 12 }
];

const priceLimit = 12;

// Create the query using $or with the two conditions
// Your code here

Need a hint?

Use $or with an array of two condition objects inside the query object.

4

Complete the query by finding matching books

Create a variable called matchingBooks and assign it the result of filtering books using the query conditions with $or logic.

MongoDB

const books = [
  { title: "The Great Gatsby", author: "F. Scott Fitzgerald", price: 10 },
  { title: "1984", author: "George Orwell", price: 15 },
  { title: "To Kill a Mockingbird", author: "Harper Lee", price: 8 },
  { title: "The Catcher in the Rye", author: "J.D. Salinger", price: 12 }
];

const priceLimit = 12;

const query = {
  $or: [
    { author: "George Orwell" },
    { price: { $lt: priceLimit } }
  ]
};

// Filter books using the $or query logic
// Your code here

Need a hint?

Use Array.filter and Array.some to apply the $or conditions.