PUT request in Postman

Introduction

A PUT request updates or replaces data on a server. It helps keep information current.

When you want to update a user's profile information completely.

When fixing a mistake in a stored record by replacing it.

When uploading a new version of a file to a server.

When setting a resource to a specific state, replacing old data.

When testing API endpoints that modify existing data.

Syntax

Postman

PUT /resource/identifier HTTP/1.1
Host: example.com
Content-Type: application/json

{
  "key": "value",
  "another_key": "another_value"
}

The URL includes the resource identifier to specify what to update.

The request body contains the new data to replace the old resource.

Examples

This updates user with ID 123 with new name and email.

Postman

PUT /users/123 HTTP/1.1
Host: api.example.com
Content-Type: application/json

{
  "name": "Alice",
  "email": "[e-mail]"
}

This replaces product 456 details with new name and price.

Postman

PUT /products/456 HTTP/1.1
Host: api.example.com
Content-Type: application/json

{
  "name": "New Product",
  "price": 19.99
}

Sample Program

This example updates the todo item with ID 1 to new details.

Postman

PUT /todos/1 HTTP/1.1
Host: jsonplaceholder.typicode.com
Content-Type: application/json

{
  "userId": 1,
  "title": "Buy groceries",
  "completed": false
}

Important Notes

PUT replaces the entire resource; partial updates need PATCH.

Always include Content-Type header when sending JSON data.

Check server response to confirm update success (usually 200 or 204 status).

Summary

PUT requests update or replace existing data on the server.

They require the full new data in the request body.

Use PUT when you want to set a resource to a specific state.

Practice

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

easy

A. To update or replace an existing resource on the server

B. To retrieve data from the server

C. To delete a resource from the server

D. To create a new resource without replacing existing data

Solution

1. Step 1: Understand HTTP methods

   PUT is used to update or replace existing data, unlike GET which retrieves data or DELETE which removes data.

2. Step 2: Match PUT request purpose

   PUT requires sending the full new data to replace the existing resource, so it updates or replaces it.

3. Final Answer:

   To update or replace an existing resource on the server -> Option A

4. Quick Check:

   PUT updates/replaces resource = A [OK]

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

Common Mistakes:

• Confusing PUT with GET or POST
• Thinking PUT creates new resources only
• Assuming PUT partially updates data

2. Which of the following is the correct way to set up a PUT request body in Postman to update a user's name to "Alice"?

easy

A. { name = "Alice" }

B. [ "name": "Alice" ]

C. "name": "Alice"

D. { "name": "Alice" }

Solution

1. Step 1: Identify correct JSON syntax

   JSON objects use curly braces with key-value pairs in double quotes and colon separators.

2. Step 2: Validate syntax of options

   Only { "name": "Alice" } is valid JSON. The others have syntax errors like using = instead of :, square brackets, or incomplete structure.

3. Final Answer:

   { "name": "Alice" } -> Option D

4. Quick Check:

   Valid JSON body = D [OK]

Hint: Use curly braces and double quotes for JSON body [OK]

Common Mistakes:

• Using square brackets instead of braces
• Missing quotes around keys or values
• Using equals sign instead of colon

3. Given this PUT request in Postman to update a product's price:

{
  "id": 101,
  "name": "Coffee Mug",
  "price": 12.99
}

If the server replaces the entire product resource with this data, what will be the product's name after the update?

medium

A. null

B. Original name before update

C. Coffee Mug

D. Error: Missing fields

Solution

1. Step 1: Understand PUT replaces full resource

   The server replaces the entire product data with the provided JSON, so all fields sent become the new state.

2. Step 2: Check the name field in the request body

   The name is "Coffee Mug" in the JSON, so after update, the product's name will be "Coffee Mug".

3. Final Answer:

   Coffee Mug -> Option C

4. Quick Check:

   PUT replaces resource fully = Coffee Mug [OK]

Hint: PUT replaces all fields sent, so name updates to given value [OK]

Common Mistakes:

• Assuming PUT only updates changed fields
• Thinking missing fields stay unchanged
• Expecting error if some fields are missing

4. You send a PUT request in Postman but receive a 400 Bad Request error. Which of these is the most likely cause?

medium

A. The server does not support PUT requests

B. The request body is missing required fields or has invalid JSON

C. The URL is incorrect but the body is fine

D. The GET method was used instead of PUT

Solution

1. Step 1: Understand 400 Bad Request meaning

   400 error means the server could not understand the request due to invalid syntax or missing data.

2. Step 2: Analyze causes for 400 in PUT requests

   Invalid JSON or missing required fields in the body commonly cause 400 errors for PUT requests.

3. Final Answer:

   The request body is missing required fields or has invalid JSON -> Option B

4. Quick Check:

   400 error = invalid request body [OK]

Hint: Check JSON syntax and required fields for 400 errors [OK]

Common Mistakes:

• Confusing 400 with 404 Not Found
• Assuming server disallows PUT causes 400
• Mixing up HTTP methods in error cause

5. You want to update a user's profile with a PUT request in Postman. The user has fields: id, name, email, and phone. You only want to change the phone number. What is the best practice to avoid accidentally deleting other fields?

hard

A. Include all fields with current values, changing only the phone number in the PUT body

B. Send only the phone field in the PUT body

C. Use a GET request to update the phone number

D. Send an empty body with the PUT request

Solution

1. Step 1: Recall PUT replaces entire resource

   PUT replaces the whole resource with the data sent, so missing fields will be removed.

2. Step 2: Include all fields to preserve data

   To avoid deleting fields, send all current fields with updated phone number in the PUT body.

3. Final Answer:

   Include all fields with current values, changing only the phone number in the PUT body -> Option A

4. Quick Check:

   PUT replaces full data, so send all fields [OK]

Hint: Send full resource data in PUT to avoid data loss [OK]

Common Mistakes:

• Sending partial data with PUT causing data loss
• Using GET to update data
• Sending empty body expecting no changes