In and not-in queries in Firebase - Mini Project: Build & Apply

PMC: In and not-in queries

📖 Scenario: You are managing a small online store's inventory using Firebase Firestore. You want to learn how to query products based on categories they belong to or exclude certain categories.

🎯 Goal: Build Firestore queries that use in and not-in operators to filter products by their categories.

📋 What You'll Learn

Create a Firestore collection reference called productsRef pointing to 'products'

Create a list variable called categoriesToInclude with exact values ['electronics', 'books', 'clothing']

Write a Firestore query called includeQuery that finds products where the 'category' field is in categoriesToInclude

Write a Firestore query called excludeQuery that finds products where the 'category' field is not in categoriesToInclude

💡 Why This Matters

🌍 Real World

Filtering products by categories is a common task in online stores to show customers relevant items.

💼 Career

Knowing how to use Firestore queries with 'in' and 'not-in' operators is essential for building efficient and user-friendly cloud-based applications.

1

Create Firestore collection reference

Create a Firestore collection reference called productsRef that points to the 'products' collection using firebase.firestore().collection('products').

Firebase

# Your code here

Need a hint?

Use firebase.firestore().collection('products') to get the collection reference.

2

Create categories list

Create a constant array called categoriesToInclude with these exact string values: 'electronics', 'books', and 'clothing'.

Firebase

const productsRef = firebase.firestore().collection('products');
# Your code here

Need a hint?

Use square brackets [] to create the array with the exact values.

3

Write query using 'in' operator

Write a constant called includeQuery that queries productsRef using .where('category', 'in', categoriesToInclude) to find products whose category is in the list categoriesToInclude.

Firebase

const productsRef = firebase.firestore().collection('products');
const categoriesToInclude = ['electronics', 'books', 'clothing'];
# Your code here

Need a hint?

Use .where('category', 'in', categoriesToInclude) on productsRef.

4

Write query using 'not-in' operator

Write a constant called excludeQuery that queries productsRef using .where('category', 'not-in', categoriesToInclude) to find products whose category is not in the list categoriesToInclude.

Firebase

const productsRef = firebase.firestore().collection('products');
const categoriesToInclude = ['electronics', 'books', 'clothing'];
const includeQuery = productsRef.where('category', 'in', categoriesToInclude);
# Your code here

Need a hint?

Use .where('category', 'not-in', categoriesToInclude) on productsRef.