Error response format in Rest API - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this JSON error response?

Given this error response from an API, what is the value of the message field?

Rest API

{
  "error": {
    "code": 404,
    "message": "Resource not found",
    "details": "The requested item does not exist."
  }
}

A "404"

B "Resource not found"

C "The requested item does not exist."

D "error"

💡 Hint

Look inside the error object for the message key.

The message field inside the error object contains the string "Resource not found" which describes the error.

🧠 Conceptual

intermediate

Which HTTP status code is best for a validation error?

You want to send an error response when user input is invalid. Which HTTP status code should you use?

A 200 OK

B 404 Not Found

C 500 Internal Server Error

D 400 Bad Request

💡 Hint

Think about which code means the client sent bad data.

400 Bad Request means the server cannot process the request because of client error, such as invalid input.

🔧 Debug

advanced

What error does this JSON error response cause?

This API error response is sent as a string. What problem will the client face?

Rest API

"{ 'error': { 'code': 401, 'message': 'Unauthorized access' } }"

A SyntaxError due to single quotes in JSON string

B ValueError because code is not a string

C TypeError because of missing error key

D No error, valid JSON string

💡 Hint

JSON requires double quotes for keys and strings.

JSON must use double quotes for keys and string values. Single quotes cause a syntax error when parsing.

🚀 Application

advanced

How many fields are in this error response?

Count the total number of keys in this JSON error response object.

Rest API

{
  "error": {
    "code": 403,
    "message": "Forbidden",
    "details": {
      "reason": "User lacks permission",
      "timestamp": "2024-06-01T12:00:00Z"
    }
  },
  "requestId": "abc123"
}

A 5

B 3

C 6

D 4

💡 Hint

Count all keys at all levels inside the JSON object.

The keys are: error, requestId, and inside error: code, message, details. Inside details: reason, timestamp. Total keys are 5 at top two levels (error, requestId, code, message, details). Nested keys inside details are not counted as separate top-level keys.

❓ Predict Output

expert

Which option produces this error response JSON string?

You want to produce this exact JSON string as an error response: {"error":{"code":500,"message":"Internal Server Error"}}

A json.dumps({'error': {'code': 500, 'message': 'Internal Server Error'}, 'extra': None})

B json.dumps({'error': {'code': '500', 'message': 'Internal Server Error'}})

C json.dumps({'error': {'code': 500, 'message': 'Internal Server Error'}})

D json.dumps({'error': {'code': 500, 'msg': 'Internal Server Error'}})

💡 Hint

Check the exact keys and value types in the JSON string.

Option C matches the exact keys and value types. Option C uses code as string, which changes the output. Option C adds an extra key. Option C uses 'msg' instead of 'message'.