PATCH request in Postman - Build an Automation Script

Update user email using PATCH request

Preconditions (2)

Step 1: Open Postman

Step 2: Set request method to PATCH

Step 3: Enter URL https://api.example.com/users/123

Step 4: In the Headers tab, add 'Content-Type' with value 'application/json'

Step 5: In the Body tab, select raw and JSON format

Step 6: Enter JSON payload: {"email": "[e-mail]"}

Step 7: Click Send button

✅ Expected Result: Response status code is 200 OK and response body contains updated email '[e-mail]'

Automation Requirements - Postman Test Scripts

Assertions Needed:

Verify response status code is 200

Verify response body contains updated email '[e-mail]'

Best Practices:

Use environment variables for base URL and user ID

Validate response schema if available

Use descriptive test names

Automated Solution

Postman

pm.test('Status code is 200', function () {
    pm.response.to.have.status(200);
});

pm.test('Response has updated email', function () {
    const jsonData = pm.response.json();
    pm.expect(jsonData.email).to.eql('[e-mail]');
});

The first test checks that the server responded with status code 200, meaning the PATCH request was successful.

The second test parses the JSON response body and asserts that the 'email' field matches the updated email we sent.

Using pm.test helps organize tests with clear names. pm.response.to.have.status and pm.expect are Postman assertion methods.

Common Mistakes - 4 Pitfalls

{'mistake': 'Not setting Content-Type header to application/json', 'why_bad': 'Server may reject or misinterpret the request body if content type is missing or incorrect.', 'correct_approach': "Always set 'Content-Type' header to 'application/json' when sending JSON payloads."}

Using PUT instead of PATCH for partial update

Not verifying response status code

Hardcoding URLs and data instead of using variables

Bonus Challenge

Now add data-driven testing with 3 different email inputs to update the user email

Show Hint

Practice

1. What is the main purpose of a PATCH request in Postman?

easy

A. To update only specific fields of a resource without sending the entire data

B. To create a new resource on the server

C. To delete a resource completely

D. To retrieve data from the server

Solution

1. Step 1: Understand HTTP methods

   PATCH is used to update part of a resource, unlike POST (create) or DELETE (remove).

2. Step 2: Identify PATCH usage in Postman

   PATCH sends only the fields to update, not the whole resource.

3. Final Answer:

   To update only specific fields of a resource without sending the entire data -> Option A

4. Quick Check:

   PATCH updates part of resource = D [OK]

Hint: PATCH updates partial data, not full resource [OK]

Common Mistakes:

• Confusing PATCH with POST or PUT
• Thinking PATCH deletes data
• Assuming PATCH retrieves data

2. Which of the following is the correct way to set a PATCH request body in Postman to update the user's email?

easy

A. { "email": "[e-mail]" }

B. [ "email": "[e-mail]" ]

C. "email": "[e-mail]"

D. [e-mail]

Solution

1. Step 1: Recognize JSON format for PATCH body

   PATCH body must be valid JSON with key-value pairs inside curly braces.

2. Step 2: Check each option's syntax

   { "email": "[e-mail]" } uses correct JSON object syntax. Options A, C, D are invalid JSON or XML.

3. Final Answer:

   { "email": "[e-mail]" } -> Option A

4. Quick Check:

   Valid JSON object = B [OK]

Hint: Use JSON object with braces for PATCH body [OK]

Common Mistakes:

• Using square brackets instead of braces
• Omitting braces around JSON
• Using XML tags instead of JSON

3. Given this PATCH request in Postman to update a user's phone number:

{
  "phone": "[phone]"
}

If the server responds with status 200 and the updated user data including the new phone, what does this indicate?

medium

A. The request failed due to missing fields

B. The entire user data was replaced

C. The server ignored the PATCH request

D. The phone number was successfully updated partially

Solution

1. Step 1: Analyze PATCH request and response

   PATCH updates part of resource; status 200 means success; response shows updated data.

2. Step 2: Interpret server behavior

   Since only phone was sent and updated, server partially updated resource successfully.

3. Final Answer:

   The phone number was successfully updated partially -> Option D

4. Quick Check:

   PATCH success with 200 = partial update C [OK]

Hint: Status 200 + partial data = PATCH success [OK]

Common Mistakes:

• Assuming PATCH replaces entire resource
• Thinking 200 means failure
• Ignoring response content

4. You sent a PATCH request in Postman but received a 400 Bad Request error. Which of these is the most likely cause?

medium

A. The URL is correct but the method should be GET

B. The server does not support PATCH method

C. The request body is missing or malformed JSON

D. The response body is empty

Solution

1. Step 1: Understand 400 Bad Request meaning

   400 means client sent invalid request, often bad syntax or missing data.

2. Step 2: Check PATCH request common errors

   Malformed or missing JSON body is a frequent cause of 400 in PATCH requests.

3. Final Answer:

   The request body is missing or malformed JSON -> Option C

4. Quick Check:

   400 error = bad request body A [OK]

Hint: Check JSON body format if 400 error occurs [OK]

Common Mistakes:

• Confusing 400 with server errors
• Ignoring request body format
• Assuming method is unsupported without checking

5. You want to update a user's profile with a PATCH request in Postman. The user has fields: name, email, and address. You only want to update the address but accidentally send the entire user object with email set to null. What is the likely outcome?

hard

A. Only address updates; email remains unchanged

B. The address updates, but email becomes null on the server

C. The server rejects the request due to null email

D. The entire user profile is deleted

Solution

1. Step 1: Understand PATCH partial update behavior

   PATCH updates fields sent; if a field is sent as null, server may update it to null.

2. Step 2: Analyze sending entire object with null email

   Sending email as null means server likely sets email to null, not ignoring it.

3. Final Answer:

   The address updates, but email becomes null on the server -> Option B

4. Quick Check:

   PATCH sends null field = field updated to null A [OK]

Hint: PATCH null field updates it to null on server [OK]

Common Mistakes:

• Assuming null fields are ignored
• Thinking PATCH only updates non-null fields
• Expecting server to reject null values always