$nor operator behavior in MongoDB - Mini Project: Build & Apply

$nor Operator Behavior in MongoDB Queries

📖 Scenario: You are managing a small online bookstore database. You want to find books that do not match certain conditions, such as not being in a specific genre and not having a rating above a certain value.

🎯 Goal: Build a MongoDB query using the $nor operator to find books that do not meet either of two conditions.

📋 What You'll Learn

Create a collection called books with 4 documents having fields title, genre, and rating.

Create a variable called queryConditions that holds an array of two conditions: one for genre equal to Fantasy, and one for rating greater than 4.5.

Write a MongoDB query using $nor with queryConditions to find books that are neither Fantasy genre nor have a rating above 4.5.

Assign the final query object to a variable called finalQuery.

💡 Why This Matters

🌍 Real World

Filtering data in MongoDB to exclude certain categories or values is common in applications like online stores, libraries, or user management systems.

💼 Career

Understanding $nor helps you write complex queries to retrieve exactly the data you need, a valuable skill for backend developers and data analysts working with MongoDB.

1

Create the books collection with sample documents

Create a variable called books and assign it an array with these exact 4 documents: { title: 'The Hobbit', genre: 'Fantasy', rating: 4.8 }, { title: '1984', genre: 'Dystopian', rating: 4.6 }, { title: 'Clean Code', genre: 'Programming', rating: 4.7 }, and { title: 'Cooking 101', genre: 'Cooking', rating: 4.2 }.

MongoDB

// Create the books array with 4 documents
// Your code here

Need a hint?

Use an array of objects with the exact field names and values.

2

Create the queryConditions array with two conditions

Create a variable called queryConditions and assign it an array with two objects: one with { genre: 'Fantasy' } and the other with { rating: { $gt: 4.5 } }.

MongoDB

const books = [
  { title: 'The Hobbit', genre: 'Fantasy', rating: 4.8 },
  { title: '1984', genre: 'Dystopian', rating: 4.6 },
  { title: 'Clean Code', genre: 'Programming', rating: 4.7 },
  { title: 'Cooking 101', genre: 'Cooking', rating: 4.2 }
];

// Create queryConditions array with two conditions
// Your code here

Need a hint?

Use an array with two objects exactly as shown.

3

Write the MongoDB query using $nor with queryConditions

Create a variable called finalQuery and assign it an object with the $nor operator using the queryConditions array.

MongoDB

const books = [
  { title: 'The Hobbit', genre: 'Fantasy', rating: 4.8 },
  { title: '1984', genre: 'Dystopian', rating: 4.6 },
  { title: 'Clean Code', genre: 'Programming', rating: 4.7 },
  { title: 'Cooking 101', genre: 'Cooking', rating: 4.2 }
];

const queryConditions = [
  { genre: 'Fantasy' },
  { rating: { $gt: 4.5 } }
];

// Create finalQuery using $nor with queryConditions
// Your code here

Need a hint?

Use an object with $nor as the key and queryConditions as the value.

4

Complete the query setup for use in MongoDB

Add a comment above finalQuery explaining that this query finds books that are neither Fantasy genre nor have a rating above 4.5.

MongoDB

const books = [
  { title: 'The Hobbit', genre: 'Fantasy', rating: 4.8 },
  { title: '1984', genre: 'Dystopian', rating: 4.6 },
  { title: 'Clean Code', genre: 'Programming', rating: 4.7 },
  { title: 'Cooking 101', genre: 'Cooking', rating: 4.2 }
];

const queryConditions = [
  { genre: 'Fantasy' },
  { rating: { $gt: 4.5 } }
];

// Add a comment explaining the purpose of finalQuery
const finalQuery = { $nor: queryConditions };

Need a hint?

Write a clear comment above the finalQuery variable.