Collection variables in Postman - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set a collection variable named 'token' with value 'abc123'.

Postman

pm.collectionVariables.set('[1]', 'abc123');

Drag options to blanks, or click blank then click option'

Atoken

BauthToken

CsessionId

DuserId

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong variable name like 'authToken' instead of 'token'.

Forgetting to put the variable name as a string.

The collection variable name is 'token'. This code sets it to 'abc123'.

2fill in blank

medium

Complete the code to get the value of the collection variable 'userId'.

Postman

const userId = pm.collectionVariables.get('[1]');

Drag options to blanks, or click blank then click option'

AauthToken

BuserId

CsessionId

Dtoken

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different variable name like 'token' instead of 'userId'.

Not using quotes around the variable name.

To get the value of the collection variable 'userId', use pm.collectionVariables.get('userId').

3fill in blank

hard

Fix the error in the code to correctly delete the collection variable named 'sessionId'.

Postman

pm.collectionVariables.[1]('sessionId');

Drag options to blanks, or click blank then click option'

Adelete

Bremove

Cunset

Dclear

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'remove' or 'unset' which are not valid methods.

Using 'clear' which clears all variables, not one.

The correct method to delete a collection variable is delete. So use pm.collectionVariables.delete('sessionId').

4fill in blank

hard

Fill both blanks to check if the collection variable 'token' exists and then log its value.

Postman

if (pm.collectionVariables.[1]('[2]')) {
  console.log(pm.collectionVariables.get('token'));
}

Drag options to blanks, or click blank then click option'

Ahas

Bexists

Ccontains

Dtoken

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'exists' or 'contains' which are not valid methods.

Using wrong variable name in the second blank.

The method to check if a collection variable exists is has. The variable name is 'token'.

5fill in blank

hard

Fill all three blanks to update the collection variable 'count' by increasing its value by 1.

Postman

let current = parseInt(pm.collectionVariables.get('[1]')) || 0;
current = current [2] 1;
pm.collectionVariables.set('[3]', current.toString());

Drag options to blanks, or click blank then click option'

Acount

B+

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-' instead of '+' causing decrement.

Using different variable names in get and set.

We get the 'count' variable, add 1 using '+', then set it back to 'count'.

Practice

1. What is the main purpose of collection variables in Postman?

easy

A. To store reusable values accessible by all requests in a collection

B. To store environment-specific URLs only

C. To save responses from API calls automatically

D. To create user interface themes in Postman

Solution

1. Step 1: Understand what collection variables do

   Collection variables hold values that can be reused across all requests in a collection, making tests easier to manage.

2. Step 2: Compare options with this purpose

   Only To store reusable values accessible by all requests in a collection describes storing reusable values for all requests, which matches the purpose of collection variables.

3. Final Answer:

   To store reusable values accessible by all requests in a collection -> Option A

4. Quick Check:

   Collection variables = reusable values [OK]

Hint: Remember: collection variables share values across all collection requests [OK]

Common Mistakes:

• Confusing collection variables with environment variables
• Thinking collection variables store API responses
• Assuming collection variables control UI settings

2. Which syntax correctly uses a collection variable named api_key inside a request URL in Postman?

easy

A. https://api.example.com/data?key=api_key

B. https://api.example.com/data?key=[api_key]

C. https://api.example.com/data?key=$api_key

D. https://api.example.com/data?key={{api_key}}

Solution

1. Step 1: Recall Postman variable syntax

   Postman uses double curly braces {{variable_name}} to insert variables into requests.

2. Step 2: Match syntax with options

   Only https://api.example.com/data?key={{api_key}} uses {{api_key}}, which is the correct way to reference a collection variable.

3. Final Answer:

   https://api.example.com/data?key={{api_key}} -> Option D

4. Quick Check:

   Variable syntax = {{variable_name}} [OK]

Hint: Use double curly braces {{}} to insert variables in Postman [OK]

Common Mistakes:

• Using plain variable name without braces
• Using square brackets or dollar sign instead of {{}}
• Confusing environment and collection variable syntax

3. Given a collection variable base_url set to https://api.test.com, what will be the full URL for this request?

GET {{base_url}}/users

medium

A. GET https://api.test.com/users

B. GET {{base_url}}/users

C. GET https://api.test.com{{base_url}}/users

D. GET /users

Solution

1. Step 1: Substitute the collection variable

   The variable {{base_url}} is replaced by its value https://api.test.com in the request URL.

2. Step 2: Combine the parts of the URL

   After substitution, the URL becomes https://api.test.com/users as the path /users is appended.

3. Final Answer:

   GET https://api.test.com/users -> Option A

4. Quick Check:

   Variable replaced by value = full URL [OK]

Hint: Replace {{variable}} with its value to get the full URL [OK]

Common Mistakes:

• Not replacing the variable and leaving {{base_url}} as is
• Appending variable value incorrectly
• Ignoring the path after the variable

4. You set a collection variable token but your request still sends Authorization: Bearer {{token}} literally without replacing it. What is the likely cause?

medium

A. You used single curly braces instead of double

B. The collection variable token was not saved properly

C. Postman does not support collection variables in headers

D. The variable name is case-insensitive and mismatched

Solution

1. Step 1: Understand variable replacement behavior

   If Postman sends {{token}} literally, it means the variable was not found or set correctly.

2. Step 2: Identify common causes

   Most often, the variable was not saved or defined in the collection variables, so Postman cannot replace it.

3. Final Answer:

   The collection variable token was not saved properly -> Option B

4. Quick Check:

   Missing variable value = no replacement [OK]

Hint: Check if collection variable is saved before using it [OK]

Common Mistakes:

• Assuming single braces work for variables
• Thinking headers can't use variables
• Ignoring case sensitivity issues

5. You want to use a collection variable user_id in a request body JSON like this:

{ "id": "{{user_id}}", "action": "delete" }

But the API expects id as a number, not a string. How should you fix the request body to send user_id as a number?

hard

A. { "id": "{{user_id}}", "action": "delete" }

B. { "id": '${{user_id}}', "action": "delete" }

C. { "id": {{user_id}}, "action": "delete" }

D. { "id": [{{user_id}}], "action": "delete" }

Solution

1. Step 1: Understand JSON data types

   In JSON, numbers should not be inside quotes; quotes make them strings.

2. Step 2: Adjust variable usage in JSON

   Remove quotes around {{user_id}} so Postman inserts the number directly, matching API expectation.

3. Final Answer:

   { "id": {{user_id}}, "action": "delete" } -> Option C

4. Quick Check:

   Numbers in JSON = no quotes [OK]

Hint: Remove quotes around {{variable}} to send numbers, not strings [OK]

Common Mistakes:

• Keeping quotes around numeric variables
• Using wrong variable syntax with $ or []
• Sending arrays instead of single values