Error response structure in Rest API - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the HTTP status code for an error response.

Rest API

response.status_code = [1]

Drag options to blanks, or click blank then click option'

A404

B200

C500

D302

Attempts:

3 left

💡 Hint

Common Mistakes

Using 200 which means success.

Using 302 which is for redirection.

The status code 500 indicates an internal server error, which is commonly used for error responses.

2fill in blank

medium

Complete the JSON error response body with the correct key for the error message.

Rest API

{
  "error": {
    "[1]": "Resource not found"
  }
}

Drag options to blanks, or click blank then click option'

Amessage

Bcode

Cstatus

Ddetail

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'code' which usually holds numeric error codes.

Using 'status' which is often the HTTP status code.

The key message is commonly used to describe the error details in the response body.

3fill in blank

hard

Fix the error in the error response JSON by completing the missing key for the error code.

Rest API

{
  "error": {
    "[1]": 404,
    "message": "Not Found"
  }
}

Drag options to blanks, or click blank then click option'

Astatus

Bcode

Cerror_code

Dhttp_code

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'status' which can be confused with HTTP status.

Using 'http_code' which is less common.

The key code is the standard way to represent the error code in many APIs.

4fill in blank

hard

Fill both blanks to create a complete error response with status and message keys.

Rest API

{
  "error": {
    "[1]": 401,
    "[2]": "Unauthorized access"
  }
}

Drag options to blanks, or click blank then click option'

Acode

Bmessage

Cstatus

Ddetail

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping the keys or using uncommon key names.

The status key holds the error code, and message holds the error description.

5fill in blank

hard

Fill all three blanks to create a detailed error response with code, message, and details keys.

Rest API

{
  "error": {
    "[1]": 403,
    "[2]": "Forbidden",
    "[3]": "You do not have permission to access this resource."
  }
}

Drag options to blanks, or click blank then click option'

Acode

Bmessage

Cdetails

Dstatus

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'status' instead of 'code'.

Confusing 'details' with 'message'.

The code key holds the error number, message gives a short description, and details provides more information.

Practice

1. What is the main purpose of an error response structure in a REST API?

easy

A. To clearly communicate what went wrong during a request

B. To speed up the API response time

C. To store user data securely

D. To format the successful response data

Solution

1. Step 1: Understand the role of error responses

   Error responses are sent when something goes wrong to inform the user or client about the issue.

2. Step 2: Identify the purpose of the error structure

   The structure helps communicate the problem clearly, usually with a code and message.

3. Final Answer:

   To clearly communicate what went wrong during a request -> Option A

4. Quick Check:

   Error response = clear problem message [OK]

Hint: Error responses explain problems clearly to users [OK]

Common Mistakes:

• Thinking error responses speed up API
• Confusing error response with data storage
• Assuming error response formats success data

2. Which of the following is the correct JSON syntax for a simple error response with code 404 and message "Not Found"?

easy

A. {"error": {code: 404, message: "Not Found"}}

B. {"error": {"code": 404, "message": "Not Found"}}

C. {"error": {"code": "404", "message": Not Found}}

D. {"error": {"code": 404, message: Not Found}}

Solution

1. Step 1: Check JSON key and string syntax

   Keys and string values must be in double quotes. Numbers like 404 do not need quotes.

2. Step 2: Identify the correct option

   {"error": {"code": 404, "message": "Not Found"}} uses correct quotes for keys and strings, and number 404 without quotes.

3. Final Answer:

   {"error": {"code": 404, "message": "Not Found"}} -> Option B

4. Quick Check:

   JSON keys and strings need double quotes [OK]

Hint: Use double quotes for keys and string values in JSON [OK]

Common Mistakes:

• Missing quotes around keys
• Using quotes around numbers
• Not quoting string values

3. Given this error response JSON:

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

What is the value of the message field?

medium

A. "error"

B. 401

C. null

D. "Unauthorized access"

Solution

1. Step 1: Locate the message field in the JSON

   The message field is inside the error object and has the value "Unauthorized access".

2. Step 2: Confirm the value type

   The value is a string, so it includes the quotes in JSON representation.

3. Final Answer:

   "Unauthorized access" -> Option D

4. Quick Check:

   message field value = "Unauthorized access" [OK]

Hint: Look inside error object for message value [OK]

Common Mistakes:

• Confusing code with message
• Selecting the key name instead of value
• Assuming null when field exists

4. You receive this error response from your API:

{"error": {"code": "400", "message": "Bad Request"}}

Why might this cause problems in your client code expecting code as a number?

medium

A. Because the error key is misspelled

B. Because the message is missing

C. Because the code is a string, not a number, causing type errors

D. Because the JSON is invalid

Solution

1. Step 1: Identify the data type of code field

   The code field is given as a string "400" instead of a number 400.

2. Step 2: Understand client expectations

   If client expects a number, receiving a string can cause type errors or failed comparisons.

3. Final Answer:

   Because the code is a string, not a number, causing type errors -> Option C

4. Quick Check:

   Type mismatch in code field causes errors [OK]

Hint: Check if code is number, not string, to avoid type errors [OK]

Common Mistakes:

• Ignoring type differences
• Assuming message is missing
• Thinking JSON is invalid

5. You want to design an error response structure that includes an error code, a message, and optionally a list of field errors for validation issues. Which JSON structure below correctly supports this?

hard

A. {"error": {"code": 422, "message": "Validation failed", "fields": [{"field": "email", "error": "Invalid format"}]}}

B. {"error": {"code": 422, "message": "Validation failed", "fields": "email: Invalid format"}}

C. {"error": {"code": 422, "message": "Validation failed", "fields": {"email": "Invalid format"}}}

D. {"error": {"code": 422, "message": "Validation failed", "fields": ["email", "Invalid format"]}}

Solution

1. Step 1: Understand the need for multiple field errors

   We want a list of objects, each with a field name and its error message.

2. Step 2: Check each option's fields format

   {"error": {"code": 422, "message": "Validation failed", "fields": [{"field": "email", "error": "Invalid format"}]}} uses an array of objects with field and error keys, which is clear and extensible.

3. Step 3: Identify why others are incorrect

   {"error": {"code": 422, "message": "Validation failed", "fields": "email: Invalid format"}} uses a string instead of structured data; {"error": {"code": 422, "message": "Validation failed", "fields": {"email": "Invalid format"}}} uses an object but not a list; {"error": {"code": 422, "message": "Validation failed", "fields": ["email", "Invalid format"]}} uses a list mixing field and message without keys.

4. Final Answer:

   {"error": {"code": 422, "message": "Validation failed", "fields": [{"field": "email", "error": "Invalid format"}]}} -> Option A

5. Quick Check:

   Use array of objects for detailed field errors [OK]

Hint: Use array of objects for multiple field errors [OK]

Common Mistakes:

• Using plain strings instead of structured objects
• Mixing field names and messages in arrays without keys
• Using object instead of list for multiple errors