PATCH request in Postman - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a PATCH request in API testing?

A PATCH request is used to update part of a resource on the server without sending the entire data. It changes only the specified fields.

beginner

How does a PATCH request differ from a PUT request?

PATCH updates only specified fields of a resource, while PUT replaces the entire resource with the new data.

beginner

In Postman, which HTTP method should you select to send a PATCH request?

Select the 'PATCH' method from the dropdown next to the request URL to send a PATCH request.

beginner

What status code usually indicates a successful PATCH request?

Status code 200 (OK) or 204 (No Content) usually indicates a successful PATCH request.

intermediate

Why is PATCH request useful in testing APIs?

PATCH allows testing partial updates efficiently, saving bandwidth and time by not sending full data when only some fields change.

What does a PATCH request do?

A Creates a new resource

B Updates part of a resource

C Deletes a resource

D Replaces the entire resource

PATCH updates only specified parts of a resource, unlike PUT which replaces the whole resource.

Which HTTP status code indicates a successful PATCH request with no content returned?

A 500

B 201

C 404

D 204

204 No Content means the PATCH request succeeded but the server returns no content.

In Postman, how do you specify a PATCH request?

A Select PATCH method

B Select DELETE method

C Select GET method

D Select POST method

You must select PATCH from the HTTP method dropdown to send a PATCH request.

Which method should you use to update an entire resource?

A PATCH

B GET

C PUT

D DELETE

PUT replaces the entire resource, unlike PATCH which updates parts.

Why might you prefer PATCH over PUT in API testing?

A PATCH is faster for partial updates

B PATCH deletes resources

C PATCH creates new resources

D PATCH returns full resource always

PATCH is efficient for partial updates because it sends only changed data.

Explain what a PATCH request is and when you would use it in API testing.

Think about updating only a part of a profile instead of the whole profile.

Describe how to send a PATCH request using Postman and how to verify it was successful.

Remember the HTTP method dropdown and response codes.

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