Nested error reporting in Rest API - Mini Project: Build & Apply

Nested Error Reporting in REST API

📖 Scenario: You are building a REST API that receives user data. Sometimes, the data has errors inside nested parts, like an address inside a user profile. You want to collect all errors, including those inside nested data, and send them back in a clear way.

🎯 Goal: Create a Python dictionary that represents nested error messages for a user profile API. Then, write code to extract and display these nested errors clearly.

📋 What You'll Learn

Create a nested dictionary called errors with specific error messages

Create a variable error_count to count total errors

Use a nested for loop to count all errors inside the nested dictionary

Print the total number of errors found

💡 Why This Matters

🌍 Real World

APIs often receive complex data with nested parts. Reporting all errors clearly helps users fix their input quickly.

💼 Career

Backend developers and API designers need to handle nested error reporting to improve user experience and debugging.

1

Create nested error dictionary

Create a dictionary called errors with these exact entries: 'username': 'Required field', 'email': 'Invalid format', and a nested dictionary 'address' with 'street': 'Missing' and 'zipcode': 'Invalid'.

Rest API

# Create the nested dictionary called errors
# Your code here

Hint

Use a dictionary with keys 'username', 'email', and 'address'. The 'address' key holds another dictionary.

2

Add error count variable

Create a variable called error_count and set it to 0 to start counting errors.

Rest API

errors = {
    'username': 'Required field',
    'email': 'Invalid format',
    'address': {
        'street': 'Missing',
        'zipcode': 'Invalid'
    }
}

# Create error_count variable
# Your code here

Hint

Just create a variable named error_count and set it to zero.

3

Count all errors including nested

Use a for loop with variables field and error to iterate over errors.items(). Inside the loop, check if error is a dictionary. If yes, use another for loop with subfield and suberror to iterate over error.items() and increment error_count by 1 for each nested error. Otherwise, increment error_count by 1 for the top-level error.

Rest API

errors = {
    'username': 'Required field',
    'email': 'Invalid format',
    'address': {
        'street': 'Missing',
        'zipcode': 'Invalid'
    }
}

error_count = 0

# Count errors including nested ones
# Your code here

Hint

Use isinstance(error, dict) to check if the error is nested. Then loop inside it.

4

Print total error count

Write a print statement to display the text 'Total errors:' followed by the value of error_count.

Rest API

errors = {
    'username': 'Required field',
    'email': 'Invalid format',
    'address': {
        'street': 'Missing',
        'zipcode': 'Invalid'
    }
}

error_count = 0

for field, error in errors.items():
    if isinstance(error, dict):
        for subfield, suberror in error.items():
            error_count += 1
    else:
        error_count += 1

# Print the total number of errors
# Your code here

Hint

Use an f-string to print the message and the error_count variable.

Practice

1.

What is the main purpose of nested error reporting in REST APIs?

easy

A. To show detailed errors inside nested data clearly

B. To hide errors from users

C. To speed up the API response time

D. To encrypt error messages

Solution

1. Step 1: Understand error reporting basics

   Error reporting helps identify problems in API requests or responses.

2. Step 2: Recognize nested error reporting role

   Nested error reporting shows errors inside complex or nested data structures clearly.

3. Final Answer:

   To show detailed errors inside nested data clearly -> Option A

4. Quick Check:

   Nested error reporting = detailed nested errors [OK]

Hint: Nested errors explain problems inside complex data [OK]

Common Mistakes:

• Thinking nested errors hide problems
• Confusing error reporting with encryption
• Assuming it speeds up API responses

2.

Which JSON structure correctly represents a nested error for a REST API response?

{
  "error": {
    "message": "Invalid input",
    "details": {
      "field": "email",
      "error": "Invalid format"
    }
  }
}

easy

A. { "error": "Invalid input", "details": "email error" }

B. { "message": "Invalid input", "field": "email" }

C. { "error": ["Invalid input", "email error"] }

D. { "error": { "message": "Invalid input", "details": { "field": "email", "error": "Invalid format" } } }

Solution

1. Step 1: Identify nested JSON error format

   Nested error reporting uses objects inside objects to show details clearly.

2. Step 2: Match the correct JSON structure

   { "error": { "message": "Invalid input", "details": { "field": "email", "error": "Invalid format" } } } shows an error object with a message and nested details object with field and error.

3. Final Answer:

   { "error": { "message": "Invalid input", "details": { "field": "email", "error": "Invalid format" } } } -> Option D

4. Quick Check:

   Nested JSON error = { "error": { "message": "Invalid input", "details": { "field": "email", "error": "Invalid format" } } } [OK]

Hint: Look for nested objects inside error key [OK]

Common Mistakes:

• Using arrays instead of objects for nested errors
• Missing nested details object
• Flattening error info without nesting

3.

Given this REST API error response JSON, what is the error message for the password field?

{
  "error": {
    "message": "Validation failed",
    "fields": {
      "email": "Invalid format",
      "password": "Too short"
    }
  }
}

medium

A. Validation failed

B. Invalid format

C. Too short

D. No error

Solution

1. Step 1: Locate the password field in JSON

   The password error is inside error.fields.password.

2. Step 2: Read the error message for password

   The value is "Too short", indicating the password error.

3. Final Answer:

   Too short -> Option C

4. Quick Check:

   password error message = "Too short" [OK]

Hint: Find error under error.fields.password [OK]

Common Mistakes:

• Choosing top-level message instead of field error
• Confusing email error with password error
• Ignoring nested fields object

4.

Identify the error in this nested error JSON response:

{
  "error": {
    "message": "Invalid data",
    "details": [
      { "field": "username", "error": "Required" },
      { "field": "age", "error": 25 }
    ]
  }
}

medium

A. The 'error' value for 'age' should be a string, not a number

B. The 'details' key should be a string, not an array

C. The 'message' key is missing

D. The 'field' keys should be numbers

Solution

1. Step 1: Check error value types in details array

   Each error value should be a descriptive string, not a number.

2. Step 2: Identify incorrect error value

   The 'age' field has error value 25 (number), which is incorrect.

3. Final Answer:

   The 'error' value for 'age' should be a string, not a number -> Option A

4. Quick Check:

   Error values must be strings [OK]

Hint: Error messages must be strings, not numbers [OK]

Common Mistakes:

• Ignoring type mismatch in error values
• Thinking details must be string instead of array
• Missing the message key

5.

You want to design a nested error response for a REST API that validates a user profile with nested address fields. Which JSON structure best represents errors for both the email and nested address.zipcode fields?

hard

A. { "error": { "email": "Invalid", "address.zipcode": "Missing" } }

B. { "error": { "fields": { "email": "Invalid", "address": { "zipcode": "Missing" } } } }

C. { "error": [ { "email": "Invalid" }, { "address": { "zipcode": "Missing" } } ] }

D. { "error": "Invalid email and missing zipcode" }

Solution

1. Step 1: Understand nested error reporting for nested fields

   Nested fields like address.zipcode should be represented as nested objects.

2. Step 2: Evaluate JSON options for nested structure

   { "error": { "fields": { "email": "Invalid", "address": { "zipcode": "Missing" } } } } uses a 'fields' object with 'email' error and nested 'address' object containing 'zipcode' error.

3. Final Answer:

   { "error": { "fields": { "email": "Invalid", "address": { "zipcode": "Missing" } } } } -> Option B

4. Quick Check:

   Nested fields use nested objects = { "error": { "fields": { "email": "Invalid", "address": { "zipcode": "Missing" } } } } [OK]

Hint: Use nested objects for nested field errors [OK]

Common Mistakes:

• Using dot notation keys instead of nested objects
• Flattening nested errors into arrays
• Combining all errors into one string