PUT for full replacement in Rest API - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the result of a PUT request replacing a resource?

Consider a REST API where a resource at /users/123 currently has the data:

{"name": "Alice", "age": 30, "city": "New York"}

A client sends a PUT request to /users/123 with the body:

{"name": "Alice", "age": 31}

What will be the state of the resource after this PUT request?

A {"name": "Alice", "age": 31, "city": "New York"}

B {"name": "Alice", "age": 31}

C {"name": "Alice", "age": 30, "city": "New York"}

D {"name": "Alice", "age": 31, "city": null}

💡 Hint

Remember that PUT replaces the entire resource, not just updates parts.

A PUT request replaces the entire resource with the data sent. Since the city field is missing in the PUT body, it will be removed from the resource.

🧠 Conceptual

intermediate

Which HTTP method is best for full replacement of a resource?

You want to replace an entire resource on the server with new data. Which HTTP method should you use?

A POST

B GET

C PUT

D PATCH

💡 Hint

One method is designed to replace the entire resource, while another updates parts.

PUT is used to fully replace a resource. PATCH is for partial updates. POST is for creating new resources or other actions. GET is for retrieving data.

🔧 Debug

advanced

Why does this PUT request not update the resource as expected?

A developer sends a PUT request to update a user resource with the following JSON body:

{"name": "Bob", "age": 25}

But after the request, the resource still has the old data including city. The server code handling the PUT is:

def put_user(user_id, data):
    user = get_user(user_id)
    user.update(data)
    save_user(user)

Why does the resource not get fully replaced?

Rest API

def put_user(user_id, data):
    user = get_user(user_id)
    user.update(data)
    save_user(user)

A The code uses update(), which merges data instead of replacing the resource.

B The server should use PATCH instead of PUT for full replacement.

C The save_user function is missing a commit call.

D The get_user function returns a copy, so changes are lost.

💡 Hint

Think about what update() does to a dictionary.

The update() method merges the new data into the existing resource, so fields not in the new data remain unchanged. This means the resource is not fully replaced as expected by PUT semantics.

📝 Syntax

advanced

Which JSON body is valid for a PUT request replacing a resource?

You want to send a PUT request to replace a resource. Which JSON body is syntactically valid?

A {"name": "Eve", "age": 29}

B {name: "Eve", age: 29}

C {"name": "Eve" "age": 29}

D {"name": "Eve", "age": 29,}

💡 Hint

Remember JSON syntax rules for commas and quotes.

Option A is valid JSON. Option A has a trailing comma which is invalid. Option A is missing a comma between fields. Option A uses unquoted keys, which is invalid in JSON.

🚀 Application

expert

What happens if a PUT request omits required fields in the resource?

A REST API requires the fields name, age, and email for a user resource.

A client sends a PUT request with the body:

{"name": "Sam", "age": 40}

The email field is missing. What is the expected server behavior according to REST principles?

A The server ignores the PUT and leaves the resource unchanged.

B The server replaces the resource without <code>email</code>, possibly causing invalid data.

C The server merges the data and keeps the old <code>email</code> value.

D The server rejects the request with a 400 Bad Request error due to missing required fields.

💡 Hint

Think about data validation and the meaning of PUT replacing the entire resource.

Since PUT replaces the entire resource, missing required fields mean the resource would be incomplete. The server should reject the request with a 400 error to enforce data integrity.