Webhook payload design in Rest API - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this webhook payload validation code?

Consider a webhook payload validation function that checks if the payload contains the required fields event and timestamp. What will be the output of the following code when given the payload {"event": "user_signup", "timestamp": 1680000000}?

Rest API

def validate_payload(payload):
    required_fields = ['event', 'timestamp']
    for field in required_fields:
        if field not in payload:
            return f"Missing field: {field}"
    return "Payload valid"

payload = {"event": "user_signup", "timestamp": 1680000000}
print(validate_payload(payload))

A Payload valid

B Missing field: timestamp

C Missing field: event

D KeyError

💡 Hint

Check if all required keys exist in the payload dictionary.

The function checks for both 'event' and 'timestamp' keys. Since both are present, it returns 'Payload valid'.

🧠 Conceptual

intermediate

Which option best describes the purpose of including a signature in a webhook payload?

Why do webhook payloads often include a signature or hash value?

A To encrypt the payload data for privacy

B To compress the payload for faster transmission

C To verify the payload integrity and authenticity

D To format the payload as JSON

💡 Hint

Think about how the receiver can trust the source of the webhook.

The signature allows the receiver to verify that the payload was sent by a trusted source and was not altered during transmission.

🔧 Debug

advanced

What error does this webhook payload parsing code raise?

Given the following Python code that parses a webhook payload, what error will it raise?

Rest API

import json

def parse_payload(payload_str):
    data = json.loads(payload_str)
    return data['user']['id']

payload = '{"user": null}'
print(parse_payload(payload))

A KeyError

B TypeError

C ValueError

D AttributeError

💡 Hint

Consider what happens when you try to access a key on a NoneType object.

The 'user' key exists but its value is null (None in Python). Trying to access ['id'] on None causes a TypeError.

📝 Syntax

advanced

Which option produces the correct JSON payload with nested data?

Which of the following strings is a valid JSON payload representing a webhook event with nested user data?

A {"event": "order_created", "user": {"id": 123, "name": Alice}}

B {'event': 'order_created', 'user': {'id': 123, 'name': 'Alice'}}

C {"event": "order_created", "user": {id: 123, name: "Alice"}}

D {"event": "order_created", "user": {"id": 123, "name": "Alice"}}

💡 Hint

Remember JSON requires double quotes for keys and string values.

Option D uses double quotes correctly for keys and string values. Other options use single quotes or unquoted keys/values, which are invalid in JSON.

🚀 Application

expert

What is the number of top-level keys in this webhook payload?

Given the following webhook payload, how many top-level keys does it contain?

Rest API

{
  "event": "payment_received",
  "timestamp": 1680001234,
  "data": {
    "payment_id": "abc123",
    "amount": 49.99,
    "currency": "USD"
  },
  "metadata": {
    "customer_id": "cust789",
    "notes": "First payment"
  }
}

A 4

B 3

C 2

D 5

💡 Hint

Count only the keys at the outermost level of the JSON object.

The top-level keys are 'event', 'timestamp', 'data', and 'metadata', totaling 4 keys.