Page-based pagination in Rest API - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is page-based pagination in REST APIs?

Page-based pagination is a method to split large sets of data into smaller chunks called pages. Each page contains a fixed number of items, and clients request data by specifying the page number and size.

beginner

Which two parameters are commonly used in page-based pagination requests?

The two common parameters are page (the page number to fetch) and page_size or limit (how many items per page).

beginner

Why is page-based pagination useful in APIs?

It helps reduce the amount of data sent at once, improving performance and user experience by loading data in manageable parts.

intermediate

How does the server know which data to send for page=3 with page_size=10?

The server calculates the starting point as (page - 1) × page_size, so for page 3 and size 10, it sends items from index 20 to 29.

intermediate

What is a common downside of page-based pagination?

If data changes between requests (like new items added), page numbers might shift, causing users to miss or see duplicate items.

Which parameter typically specifies the number of items per page in page-based pagination?

A offset

B page_size

C cursor

D token

The page_size parameter tells the server how many items to include in each page.

If you request page=2 and page_size=5, which items does the server return?

A Items 0 to 4

B Items 2 to 6

C Items 10 to 14

D Items 5 to 9

Page 2 means the second group of 5 items, so items 5 to 9 (0-based index).

What happens if the client requests a page number beyond the available data?

A Server returns an error

B Server returns the last page again

C Server returns an empty list

D Server ignores the page parameter

The server usually returns an empty list to indicate no more data.

Which of these is a limitation of page-based pagination?

A It can cause duplicate or missing items if data changes

B It requires complex tokens

C It loads all data at once

D It does not support page numbers

If data changes between requests, page numbers may shift, causing duplicates or missing items.

What is the main benefit of using page-based pagination?

A Reduces data sent per request for better performance

B Improves API security

C Allows unlimited data retrieval

D Automatically sorts data

Page-based pagination limits data per request, improving speed and user experience.

Explain how page-based pagination works in a REST API and why it is useful.

Think about how you might read a book one chapter at a time instead of all at once.

Describe a potential problem when using page-based pagination if the data changes between requests.

Imagine a list that changes while you are flipping pages.

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