Collection variables in Postman - Cheat Sheet & Quick Revision

Recall & Review

beginner

What are Collection variables in Postman?

Collection variables are values stored at the collection level in Postman. They can be used across all requests within that collection to keep data consistent and reusable.

intermediate

How do Collection variables differ from Environment variables in Postman?

Collection variables are specific to a collection and only available within it, while Environment variables are specific to an environment and can be used across multiple collections.

beginner

How can you set a Collection variable in Postman?

You can set a Collection variable by opening the collection, going to the Variables tab, and adding a new variable name and value. You can also set it programmatically using scripts with pm.collectionVariables.set('variableName', 'value').

intermediate

What happens if a variable name exists in both Collection and Environment variables?

Postman uses variable resolution priority. Collection variables override Environment variables if they share the same name when used inside that collection.

beginner

Can Collection variables be used in pre-request scripts and tests?

Yes, Collection variables can be accessed and modified in pre-request scripts and test scripts using pm.collectionVariables.get('variableName') and pm.collectionVariables.set('variableName', 'value').

Where are Collection variables stored in Postman?

A In the Postman app settings

B Globally across all environments

C Inside a specific collection

D Only in the current request

Collection variables are stored inside a specific collection and are accessible only within that collection.

Which method sets a Collection variable in a Postman script?

A pm.environment.set()

B pm.collectionVariables.set()

C pm.globals.set()

D pm.request.set()

pm.collectionVariables.set() is used to set Collection variables programmatically.

If a variable exists in both Collection and Environment variables, which one is used inside the collection?

A Collection variable

B Global variable

C Environment variable

D Randomly chosen

Collection variables have higher priority and override Environment variables inside the collection.

Can Collection variables be used in test scripts?

A No, only Environment variables can be used

B Only if exported first

C Only in pre-request scripts

D Yes, using pm.collectionVariables.get()

Collection variables can be accessed in test scripts using pm.collectionVariables.get().

How do you add a new Collection variable in the Postman app?

A In the Collection's Variables tab

B In the Environment quick look panel

C In the Global variables tab

D In the request headers

New Collection variables are added in the Variables tab of the specific collection.

Explain what Collection variables are and how they help in managing data in Postman collections.

Think about how you keep common data like API keys or URLs consistent in a group of requests.

Describe the priority order Postman uses when resolving variables if the same name exists in Collection and Environment variables.

Consider which variable Postman picks first when two variables share the same name.

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