Variable assignment in flows in Postman - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a variable in Postman flows?

A variable in Postman flows is a named storage that holds data values which can be used and changed during the execution of the flow.

beginner

How do you assign a value to a variable in a Postman flow?

You assign a value to a variable by using the 'Set Variable' block, specifying the variable name and the value you want to store.

intermediate

What happens if you assign a new value to an existing variable in a Postman flow?

The existing variable's value is updated to the new value, replacing the old one for the rest of the flow execution.

beginner

Why is variable assignment important in Postman flows?

Variable assignment allows you to store and reuse data dynamically, making your tests flexible and able to handle different scenarios.

intermediate

Can variables assigned in one block be used in another block in Postman flows?

Yes, variables assigned in one block can be accessed and used in other blocks within the same flow, enabling data sharing across steps.

In Postman flows, which block is used to assign a value to a variable?

A Get Variable

B Set Variable

C Run Script

D Send Request

The 'Set Variable' block is specifically designed to assign or update values of variables in Postman flows.

What happens if you assign a value to a variable that already exists in a Postman flow?

A The variable value is updated to the new value

B An error occurs

C The old value is kept and new value ignored

D A new variable with a different name is created

Assigning a new value to an existing variable updates its value for the rest of the flow.

Can variables assigned in one block be accessed in another block within the same Postman flow?

A Yes, variables are shared across blocks

B No, variables are local to each block

C Only if the blocks are connected by a special link

D Only if variables are global variables

Variables assigned in one block are accessible in other blocks within the same flow, enabling data sharing.

Why should you use variables in Postman flows?

A To avoid writing any requests

B To make the flow run faster

C To store and reuse data dynamically

D To prevent errors automatically

Variables help store data that can be reused and changed, making tests flexible and dynamic.

Which of the following is NOT a correct way to assign a variable in Postman flows?

A Using the 'Set Variable' block

B Assigning a value in a script block

C Using environment variables outside the flow

D Directly typing variable name in a request URL without assignment

Typing a variable name in a request URL without assignment does not assign a value; you must use 'Set Variable' or scripts to assign.

Explain how variable assignment works in Postman flows and why it is useful.

Think about how you store and reuse information while running a test step by step.

Describe a simple example where you assign a variable in one block and use it in another block in a Postman flow.

Imagine passing a note from one friend to another to remember something important.

Practice

1. What does pm.variables.set('token', 'abc123') do in a Postman test script?

easy

A. It saves the value 'abc123' to a variable named 'token' for later use.

B. It retrieves the value of the variable 'token'.

C. It deletes the variable named 'token'.

D. It sends 'abc123' as a request header named 'token'.

Solution

1. Step 1: Understand the method pm.variables.set

   This method assigns a value to a variable in Postman scripts.

2. Step 2: Analyze the parameters

   The first parameter is the variable name 'token', the second is the value 'abc123' to store.

3. Final Answer:

   It saves the value 'abc123' to a variable named 'token' for later use. -> Option A

4. Quick Check:

   pm.variables.set saves data [OK]

Hint: Set stores data; get retrieves it [OK]

Common Mistakes:

• Confusing set with get method
• Thinking set deletes variables
• Assuming set sends data in requests

2. Which of the following is the correct syntax to assign a variable named 'userId' with value 42 in a Postman test script?

easy

A. pm.variables.get('userId', 42);

B. pm.variables.store('userId', 42);

C. pm.variables.assign('userId' = 42);

D. pm.variables.set('userId', 42);

Solution

1. Step 1: Recall the correct method for assigning variables

   The method to assign a variable is pm.variables.set(name, value).

2. Step 2: Check each option's syntax

   pm.variables.set('userId', 42); uses pm.variables.set('userId', 42); which is correct syntax.

3. Final Answer:

   pm.variables.set('userId', 42); -> Option D

4. Quick Check:

   Use pm.variables.set to assign [OK]

Hint: Set method assigns variables with (name, value) [OK]

Common Mistakes:

• Using get instead of set to assign
• Incorrect method names like assign or store
• Wrong parameter syntax with equals sign

3. Consider this Postman test script snippet:

pm.variables.set('count', 5);
pm.variables.set('count', pm.variables.get('count') + 3);
console.log(pm.variables.get('count'));

What will be printed in the console?

medium

A. 5

B. 8

C. Error

D. undefined

Solution

1. Step 1: Analyze the first assignment

   The variable 'count' is set to 5 initially.

2. Step 2: Analyze the second assignment

   It gets the current 'count' value (5), adds 3, and sets 'count' to 8.

3. Step 3: Check the console.log output

   It prints the updated value of 'count', which is 8.

4. Final Answer:

   8 -> Option B

5. Quick Check:

   5 + 3 = 8 [OK]

Hint: Get current value, add, then set updated value [OK]

Common Mistakes:

• Assuming the first value stays unchanged
• Thinking get returns undefined
• Confusing set and get usage

4. You wrote this Postman test script:

pm.variables.set('status', 'active')
pm.variables.get('status')

But the test fails because the variable 'status' is undefined. What is the likely cause?

medium

A. Variables set in one request are not available in another without environment or global scope.

B. pm.variables.get returns undefined if set is not awaited.

C. Missing semicolon after set statement causes failure.

D. Variable names cannot be strings.

Solution

1. Step 1: Understand variable scopes in Postman

   Variables set with pm.variables.set are local to the current request script and do not persist across requests.

2. Step 2: Identify why 'status' is undefined

   If you try to get 'status' in a different request without using environment or global variables, it will be undefined.

3. Final Answer:

   Variables set in one request are not available in another without environment or global scope. -> Option A

4. Quick Check:

   Local variables don't persist across requests [OK]

Hint: Use environment/global variables for cross-request data [OK]

Common Mistakes:

• Thinking semicolons affect variable persistence
• Believing get waits for set automatically
• Assuming variable names can't be strings

5. You want to save a user token from a response JSON and reuse it in the next request. Which flow correctly assigns and retrieves the token using Postman variables?

hard

A. In first request test script: pm.variables.set('token', pm.response.json().token);In next request pre-request script: const token = pm.environment.get('token');

B. In first request test script: pm.variables.set('token', pm.response.json().token);In next request pre-request script: const token = pm.variables.get('token');

C. In first request test script: pm.environment.set('token', pm.response.json().token);In next request pre-request script: const token = pm.environment.get('token');

D. In first request test script: pm.environment.set('token', pm.response.json().token);In next request pre-request script: const token = pm.variables.get('token');

Solution

1. Step 1: Identify variable scope for cross-request use

   To reuse data across requests, environment variables must be used, not local variables.

2. Step 2: Match correct set and get methods

   In first request test script: pm.environment.set('token', pm.response.json().token);
   In next request pre-request script: const token = pm.environment.get('token'); uses pm.environment.set and pm.environment.get, which correctly share data between requests.

3. Final Answer:

   Use environment variables to save and retrieve token across requests. -> Option C

4. Quick Check:

   Environment variables persist across requests [OK]

Hint: Use environment variables for data between requests [OK]

Common Mistakes:

• Using pm.variables for cross-request data
• Mixing environment and local variable methods
• Not retrieving variables in the correct scope