Query parameters in Postman

Introduction

Query parameters help send extra information to a web server in a simple way. They let you filter or customize the data you get back.

When you want to search for specific items in a list, like finding books by a certain author.

When you need to sort data, for example, showing newest products first.

When you want to limit how many results you get, like showing only 10 users per page.

When you want to filter results, such as only showing active users.

When testing APIs to check how they handle different inputs without changing the main URL.

Syntax

Postman

https://api.example.com/resource?key1=value1&key2=value2

Query parameters come after a question mark (?) in the URL.

Multiple parameters are separated by an ampersand (&).

Examples

This URL asks for users who are 25 years old.

Postman

https://api.example.com/users?age=25

This URL asks for products in the 'books' category, sorted by price from low to high.

Postman

https://api.example.com/products?category=books&sort=price_asc

This URL searches for the word 'testing' in the data.

Postman

https://api.example.com/search?q=testing

Sample Program

This test checks if the API returns only 5 users who are active.

Postman

GET https://api.example.com/users?status=active&limit=5

// In Postman, set method to GET and enter the URL with query parameters.
// Send the request and check the response for 5 active users.

Important Notes

Always encode special characters in query parameters to avoid errors.

Query parameters are case sensitive in most APIs.

Use Postman's Params tab to add query parameters easily without typing them in the URL.

Summary

Query parameters add extra details to a URL to customize API requests.

They start with '?' and use '&' to separate multiple parameters.

They help filter, sort, and limit data returned by APIs.

Practice

1. What symbol is used to start query parameters in a URL when making an API request in Postman?

easy

A. Question mark (?)

B. Ampersand (&)

C. Hash (#)

D. Slash (/)

Solution

1. Step 1: Understand URL structure

   Query parameters always start after the base URL with a question mark to separate them from the path.

2. Step 2: Identify the correct symbol

   The question mark (?) is the standard symbol to begin query parameters in URLs.

3. Final Answer:

   Question mark (?) -> Option A

4. Quick Check:

   Query parameters start with ? = C [OK]

Hint: Query parameters always start with ? in URLs [OK]

Common Mistakes:

• Using & to start query parameters instead of ?
• Confusing # (fragment) with query start
• Starting query parameters with /

2. Which of the following is the correct way to add two query parameters named user and id with values alice and 123 respectively in Postman?

easy

A. ?user=alice&id=123

B. &user=alice&id=123

C. ?user=alice#id=123

D. ?user=alice;id=123

Solution

1. Step 1: Start query parameters with ?

   The first query parameter must start with a question mark (?).

2. Step 2: Separate multiple parameters with &

   Additional parameters are separated by an ampersand (&), so user=alice&id=123 is correct.

3. Final Answer:

   ?user=alice&id=123 -> Option A

4. Quick Check:

   First ? then & between parameters = A [OK]

Hint: Start with ? then separate params with & [OK]

Common Mistakes:

• Starting with & instead of ?
• Using # instead of & to separate parameters
• Using semicolon ; instead of &

3. Given the URL https://api.example.com/data?type=fruit&color=red, what will Postman send as query parameters?

medium

A. No query parameters sent

B. type=fruit only

C. type=fruit and color=red

D. color=red only

Solution

1. Step 1: Identify all query parameters after ?

   After the question mark, parameters are separated by &. Here, we have type=fruit and color=red.

2. Step 2: Confirm both parameters are included

   Both parameters will be sent in the request as key-value pairs.

3. Final Answer:

   type=fruit and color=red -> Option C

4. Quick Check:

   Both params after ? separated by & = D [OK]

Hint: All params after ? separated by & are sent [OK]

Common Mistakes:

• Ignoring second parameter after &
• Thinking only first parameter is sent
• Confusing fragment (#) with query parameters

4. You wrote the URL https://api.example.com/search?query=books&limit10 in Postman. What is wrong with this query parameter syntax?

medium

A. Extra '&' before 'limit10'

B. Missing '=' between 'limit' and '10'

C. Query parameters should start with '&' not '?'

D. Using '=' instead of ':' between key and value

Solution

1. Step 1: Check each query parameter format

   Each parameter must be in key=value format. Here, 'limit10' lacks '='.

2. Step 2: Identify missing '=' sign

   Correct syntax should be 'limit=10' to assign value 10 to key 'limit'.

3. Final Answer:

   Missing '=' between 'limit' and '10' -> Option B

4. Quick Check:

   Each param must be key=value, '=' missing = B [OK]

Hint: Check each param has key=value format [OK]

Common Mistakes:

• Omitting '=' between key and value
• Starting query with & instead of ?
• Using ':' instead of '='

5. You want to filter API results in Postman to show only active users with role 'admin' and limit results to 5. Which query parameter string correctly achieves this?

hard

A. ?status=active&role=admin&limit=5&

B. ?status=active&role=admin&limit5

C. ?status=active;role=admin;limit=5

D. ?status=active&role=admin&limit=5

Solution

1. Step 1: Use correct key=value pairs separated by &

   Each filter must be a key=value pair, separated by &. ?status=active&role=admin&limit=5 uses correct syntax.

2. Step 2: Avoid syntax errors like missing '=' or wrong separators

   ?status=active&role=admin&limit5 misses '=' in limit, C uses semicolons instead of &, D has extra trailing & which is invalid.

3. Final Answer:

   ?status=active&role=admin&limit=5 -> Option D

4. Quick Check:

   All params key=value separated by & = A [OK]

Hint: Use key=value pairs separated by & without extra symbols [OK]

Common Mistakes:

• Missing '=' in parameters
• Using semicolons instead of &
• Adding extra & at the end