Page-based pagination in Rest API - Mini Project: Build & Apply

Page-based pagination

📖 Scenario: You are building a simple REST API that returns a list of products. Since the list can be very long, you want to show only a few products per page. This is called page-based pagination.Imagine a store website where customers can browse products page by page.

🎯 Goal: Create a REST API endpoint that returns products for a given page number and page size.You will build the data, set up pagination parameters, apply pagination logic, and finally output the paginated products.

📋 What You'll Learn

Create a list of products with exact names

Create variables for page number and page size

Use slicing to get the correct products for the current page

Print the paginated list of products

💡 Why This Matters

🌍 Real World

Page-based pagination is used in websites and apps to show large lists in smaller chunks, making it easier for users to browse.

💼 Career

Understanding pagination is important for backend developers building APIs and frontend developers displaying data efficiently.

1

Create the product list

Create a list called products with these exact strings: 'Apple', 'Banana', 'Carrot', 'Date', 'Eggplant', 'Fig', 'Grape', 'Honeydew'.

Rest API

# Create the list of products
# Your code here

Hint

Use square brackets [] to create a list and separate items with commas.

2

Set page number and page size

Create two variables: page_number set to 2 and page_size set to 3.

Rest API

products = ['Apple', 'Banana', 'Carrot', 'Date', 'Eggplant', 'Fig', 'Grape', 'Honeydew']
# Create page_number and page_size variables
# Your code here

Hint

Assign the number 2 to page_number and 3 to page_size.

3

Calculate paginated products

Create a variable start_index that calculates the first product index for the current page using page_number and page_size. Then create end_index as start_index + page_size. Finally, create paginated_products by slicing products from start_index to end_index.

Rest API

products = ['Apple', 'Banana', 'Carrot', 'Date', 'Eggplant', 'Fig', 'Grape', 'Honeydew']
page_number = 2
page_size = 3
# Calculate start_index, end_index, and paginated_products
# Your code here

Hint

Remember that list indexes start at 0, so page 1 starts at index 0.

4

Print the paginated products

Write a print statement to display the paginated_products list.

Rest API

products = ['Apple', 'Banana', 'Carrot', 'Date', 'Eggplant', 'Fig', 'Grape', 'Honeydew']
page_number = 2
page_size = 3
start_index = (page_number - 1) * page_size
end_index = start_index + page_size
paginated_products = products[start_index:end_index]
# Print the paginated_products list
# Your code here

Hint

Use print(paginated_products) to show the products on page 2.

Practice

1. What is the main purpose of page-based pagination in REST APIs?

easy

A. To split large data into smaller pages for easier loading

B. To combine all data into one large response

C. To sort data alphabetically

D. To encrypt data before sending

Solution

1. Step 1: Understand pagination concept

   Pagination divides data into smaller parts called pages to avoid sending everything at once.

2. Step 2: Identify purpose in REST APIs

   Page-based pagination uses page number and limit to load data in chunks, improving performance and user experience.

3. Final Answer:

   To split large data into smaller pages for easier loading -> Option A

4. Quick Check:

   Pagination = split data into pages [OK]

Hint: Pagination means splitting data into pages [OK]

Common Mistakes:

• Thinking pagination sorts data
• Confusing pagination with encryption
• Assuming pagination combines all data

2. Which of the following is the correct way to request page 3 with 10 items per page using query parameters?

easy

A. /items?size=10&page=3

B. /items?limit=3&page=10

C. /items?page=10&limit=3

D. /items?page=3&limit=10

Solution

1. Step 1: Identify standard query parameters

   Page-based pagination commonly uses page for page number and limit for items per page.

2. Step 2: Match parameters to values

   Requesting page 3 with 10 items means page=3 and limit=10.

3. Final Answer:

   /items?page=3&limit=10 -> Option D

4. Quick Check:

   page=3 and limit=10 [OK]

Hint: Use page=number and limit=items per page [OK]

Common Mistakes:

• Swapping page and limit values
• Using wrong parameter names like size
• Mixing up page number with limit count

3. Given the API endpoint /products?page=2&limit=5 and a total of 12 products, how many products will be returned in the response?

medium

A. 2

B. 7

C. 5

D. 12

Solution

1. Step 1: Calculate items per page

   The limit is 5, so each page should have up to 5 products.

2. Step 2: Determine products on page 2

   Page 1 has products 1-5, page 2 has products 6-10, so page 2 returns 5 products.

3. Final Answer:

   5 -> Option C

4. Quick Check:

   limit = 5 products per page [OK]

Hint: Page 2 with limit 5 returns 5 items if available [OK]

Common Mistakes:

• Counting all 12 products instead of page limit
• Assuming leftover products on page 2
• Confusing page number with total items

4. You have this code snippet for pagination parameters:

page = int(request.GET.get('page', 1))
limit = int(request.GET.get('limit', 10))
start = (page - 1) * limit
end = page * limit
items = data[start:end]

What is the error if page is 0?

medium

A. It causes negative start index, returning wrong items

B. It returns the last page instead of first

C. It raises a syntax error

D. It ignores the limit parameter

Solution

1. Step 1: Calculate start index with page=0

   start = (0 - 1) * limit = -1 * limit = negative number.

2. Step 2: Understand slicing with negative start

   Negative start index in slicing returns items from the end, causing wrong data to be returned.

3. Final Answer:

   It causes negative start index, returning wrong items -> Option A

4. Quick Check:

   page=0 causes negative start index [OK]

Hint: Page must be >= 1 to avoid negative start index [OK]

Common Mistakes:

• Assuming page=0 is valid
• Expecting syntax error instead of logic error
• Ignoring negative slicing effects

5. You want to implement page-based pagination for an API returning 23 items with a limit of 7 per page. How many pages will the client need to request to get all items?

hard

A. 3

B. 4

C. 5

D. 7

Solution

1. Step 1: Calculate full pages

   Each page holds 7 items, so 3 full pages hold 21 items (3 * 7 = 21).

2. Step 2: Calculate remaining items

   23 total items - 21 = 2 items remain, needing one more page.

3. Step 3: Total pages needed

   3 full pages + 1 partial page = 4 pages total.

4. Final Answer:

   4 -> Option B

5. Quick Check:

   23 items / 7 per page = 4 pages [OK]

Hint: Divide total items by limit, round up for pages [OK]

Common Mistakes:

• Ignoring leftover items needing extra page
• Rounding down instead of up
• Assuming pages equal limit count