Sorting with sort parameter in Rest API - Mini Project: Build & Apply

Sorting with sort parameter in REST API

📖 Scenario: You are building a simple REST API that returns a list of products. Users want to get the products sorted by price or name.

🎯 Goal: Create a REST API endpoint that returns a list of products sorted by a query parameter called sort. The sort parameter can be either price or name. If no sort parameter is given, return the products unsorted.

📋 What You'll Learn

Create a list of products with exact entries

Add a variable to read the sort parameter

Sort the products list by the sort parameter if it is price or name

Return the sorted or unsorted list as JSON

💡 Why This Matters

🌍 Real World

Sorting data by user preference is common in online stores and APIs to improve user experience.

💼 Career

Understanding how to handle query parameters and sort data is essential for backend developers working with REST APIs.

1

DATA SETUP: Create the products list

Create a list called products with these exact dictionaries: {'name': 'Apple', 'price': 5}, {'name': 'Banana', 'price': 2}, {'name': 'Cherry', 'price': 7}

Rest API

# Create the products list with exact entries
# Your code here

Hint

Use a list of dictionaries with the exact keys and values.

2

CONFIGURATION: Read the sort parameter

Create a variable called sort_param that reads the sort query parameter from request.args.get('sort')

Rest API

products = [
    {'name': 'Apple', 'price': 5},
    {'name': 'Banana', 'price': 2},
    {'name': 'Cherry', 'price': 7}
]

# Read the sort parameter from request.args
# Your code here

Hint

Use request.args.get('sort') to get the query parameter.

3

CORE LOGIC: Sort the products list by the sort parameter

If sort_param is 'price', sort products by the 'price' key. If sort_param is 'name', sort products by the 'name' key. Use the sort() method with a key argument.

Rest API

from flask import request

products = [
    {'name': 'Apple', 'price': 5},
    {'name': 'Banana', 'price': 2},
    {'name': 'Cherry', 'price': 7}
]

sort_param = request.args.get('sort')

# Sort products by price or name if sort_param matches
# Your code here

Hint

Use products.sort(key=lambda product: product['price']) to sort by price.

4

OUTPUT: Return the sorted or unsorted products as JSON

Use print(products) to display the final products list.

Rest API

from flask import request

products = [
    {'name': 'Apple', 'price': 5},
    {'name': 'Banana', 'price': 2},
    {'name': 'Cherry', 'price': 7}
]

sort_param = request.args.get('sort')

if sort_param == 'price':
    products.sort(key=lambda product: product['price'])
elif sort_param == 'name':
    products.sort(key=lambda product: product['name'])

# Print the products list
# Your code here

Hint

Use print(products) to show the list.

Practice

1. What does the sort parameter do in a REST API request?

easy

A. It filters data based on a condition.

B. It controls the order in which data is returned.

C. It limits the number of results returned.

D. It changes the data format to XML.

Solution

1. Step 1: Understand the purpose of the sort parameter

   The sort parameter is used to arrange the returned data in a specific order.

2. Step 2: Differentiate from other parameters

   Filtering limits data, limiting controls count, and format changes output type, but sorting changes order.

3. Final Answer:

   It controls the order in which data is returned. -> Option B

4. Quick Check:

   Sort parameter = controls order [OK]

Hint: Sort means order, not filter or limit [OK]

Common Mistakes:

• Confusing sort with filter
• Thinking sort limits results
• Assuming sort changes data format

2. Which of the following is the correct way to sort results by the field price in descending order using the sort parameter?

easy

A. sort=desc(price)

B. sort=price-

C. sort=-price

D. sort=price_desc

Solution

1. Step 1: Identify descending order syntax

   In REST APIs, prefixing the field with a minus sign - sorts in descending order.

2. Step 2: Match the correct syntax

   Only sort=-price correctly uses the minus prefix before the field name.

3. Final Answer:

   sort=-price -> Option C

4. Quick Check:

   Minus before field = descending sort [OK]

Hint: Use '-' before field for descending sort [OK]

Common Mistakes:

• Placing '-' after the field name
• Using function-like syntax incorrectly
• Appending '_desc' instead of '-' prefix

3. Given the API request /products?sort=-rating, what will be the order of the returned products?

medium

A. Products sorted by rating from highest to lowest.

B. Products sorted alphabetically by name.

C. Products sorted by rating from lowest to highest.

D. Products sorted by price from lowest to highest.

Solution

1. Step 1: Analyze the sort parameter

   The parameter sort=-rating means sort by the field rating in descending order.

2. Step 2: Determine the order of sorting

   Descending order means highest values first, so products with highest rating come first.

3. Final Answer:

   Products sorted by rating from highest to lowest. -> Option A

4. Quick Check:

   Minus prefix = descending order [OK]

Hint: Minus means descending, so highest values first [OK]

Common Mistakes:

• Assuming minus means ascending
• Confusing rating with price or name
• Ignoring the minus sign

4. You wrote the API request /users?sort=name- to sort users by name descending, but it returns an error. What is the problem?

medium

A. The minus sign should be before the field name, not after.

B. The field name name is invalid for sorting.

C. The sort parameter cannot be used with strings.

D. You need to use order=name_desc instead.

Solution

1. Step 1: Check the position of the minus sign

   The correct syntax places the minus sign before the field name to indicate descending order.

2. Step 2: Identify the error cause

   Using name- places the minus after the field, which is invalid and causes an error.

3. Final Answer:

   The minus sign should be before the field name, not after. -> Option A

4. Quick Check:

   Minus must prefix field for descending [OK]

Hint: Minus after field causes error; put it before [OK]

Common Mistakes:

• Placing minus after field name
• Assuming sort can't be used on strings
• Using wrong parameter like 'order'

5. You want to get a list of blog posts sorted first by date descending, then by title ascending. Which sort parameter should you use?

hard

A. sort=-title,date

B. sort=date,-title

C. sort=title,-date

D. sort=-date,title

Solution

1. Step 1: Understand multi-field sorting syntax

   Multiple fields are separated by commas; order matters for sorting priority.

2. Step 2: Apply descending and ascending correctly

   Use -date for descending date, and title without minus for ascending title.

3. Step 3: Combine fields in correct order

   First sort by date descending, then by title ascending means sort=-date,title.

4. Final Answer:

   sort=-date,title -> Option D

5. Quick Check:

   Minus before date, comma, then title ascending [OK]

Hint: List fields comma-separated; minus means descending [OK]

Common Mistakes:

• Reversing field order
• Putting minus on ascending field
• Using wrong separators like semicolon