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Rest APIprogramming~5 mins

Error codes for machine consumption in Rest API - Cheat Sheet & Quick Revision

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Recall & Review
beginner
What is the main purpose of error codes in machine consumption?
Error codes help machines understand what went wrong in a request so they can handle errors properly without human intervention.
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beginner
What HTTP status code usually means 'Resource not found'?
The HTTP status code 404 means 'Resource not found'. It tells the machine the requested data does not exist.
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intermediate
Why should error codes be standardized in APIs for machine consumption?
Standardized error codes make it easier for machines to predict and handle errors consistently across different APIs.
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intermediate
What is the difference between HTTP status codes and error codes in the response body?
HTTP status codes give a general error type, while error codes in the response body provide detailed info for machines to understand the exact problem.
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beginner
Give an example of a machine-readable error code format.
A common format is JSON with fields like {"error_code": "INVALID_INPUT", "message": "Input value is not valid"}. This helps machines parse and react to errors.
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Which HTTP status code indicates a successful request?
A500
B200
C404
D401
What does a 500 HTTP status code mean?
AServer error
BClient error
CResource not found
DUnauthorized
Why include error codes in the response body besides HTTP status codes?
ATo provide detailed error info for machines
BTo confuse the client
CTo slow down the response
DTo hide the error
Which format is best for machine-readable error codes?
APlain text
BXML
CHTML
DJSON
What does a 401 HTTP status code indicate?
ANot found
BBad request
CUnauthorized access
DSuccess
Explain why error codes are important for machines when consuming APIs.
Think about how a machine knows what went wrong without a human reading messages.
You got /3 concepts.
    Describe the difference between HTTP status codes and error codes in the response body.
    One is like a quick summary, the other is like a detailed explanation.
    You got /3 concepts.

      Practice

      (1/5)
      1.

      What is the main purpose of using error codes in a REST API?

      easy
      A. To tell machines what happened during a request
      B. To make the API run faster
      C. To change the API's URL
      D. To store user data securely

      Solution

      1. Step 1: Understand the role of error codes

        Error codes are used to communicate the result of a request to the client or machine.

      2. Step 2: Identify the correct purpose

        The main purpose is to inform machines about success or failure of requests, enabling automated handling.

      3. Final Answer:

        To tell machines what happened during a request -> Option A

      4. Quick Check:

        Error codes = communicate request status [OK]
      Hint: Error codes explain request results to machines [OK]
      Common Mistakes:
      • Thinking error codes speed up the API
      • Confusing error codes with data storage
      • Believing error codes change URLs
      2.

      Which HTTP status code correctly indicates a successful request in a REST API?

      Choose the correct code:

      easy
      A. 404
      B. 500
      C. 200
      D. 301

      Solution

      1. Step 1: Recall common HTTP status codes

        200 means OK (success), 404 means Not Found, 500 means Server Error, 301 means Redirect.

      2. Step 2: Identify success code

        200 is the standard code for a successful HTTP request.

      3. Final Answer:

        200 -> Option C

      4. Quick Check:

        Success code = 200 [OK]
      Hint: 200 means success in HTTP status codes [OK]
      Common Mistakes:
      • Choosing 404 thinking it means success
      • Confusing 500 with success
      • Selecting 301 which is a redirect
      3.

      Given this JSON error response from a REST API:

      {
  "status": 404,
  "error": "Resource not found"
}

      What does the 404 status code mean?

      medium
      A. The request was successful
      B. The requested resource does not exist
      C. The server encountered an error
      D. The client is not authorized

      Solution

      1. Step 1: Understand HTTP 404 status code meaning

        404 means the requested resource was not found on the server.

      2. Step 2: Match the error message with the code

        The message "Resource not found" confirms the meaning of 404.

      3. Final Answer:

        The requested resource does not exist -> Option B

      4. Quick Check:

        404 = resource missing [OK]
      Hint: 404 means resource missing or not found [OK]
      Common Mistakes:
      • Thinking 404 means success
      • Confusing 404 with server error
      • Assuming 404 means unauthorized
      4.

      Look at this REST API error response snippet:

      {
  "status": 200,
  "error": "Invalid input data"
}

      What is wrong with this error code usage?

      medium
      A. Status 200 should not be used with an error message
      B. The error message is missing a code
      C. Status 200 means server error
      D. The JSON format is incorrect

      Solution

      1. Step 1: Analyze the status code and message

        Status 200 means success, but the message says "Invalid input data" which is an error.

      2. Step 2: Identify the mismatch

        Using 200 with an error message is incorrect; error codes like 400 should be used for invalid input.

      3. Final Answer:

        Status 200 should not be used with an error message -> Option A

      4. Quick Check:

        Status 200 = success, not error [OK]
      Hint: Match error messages with proper error status codes [OK]
      Common Mistakes:
      • Ignoring mismatch between status and message
      • Thinking 200 can mean error
      • Assuming JSON format is wrong
      5.

      You want to design a REST API that returns error codes machines can easily understand and act on. Which approach is best?

      Choose the best practice:

      hard
      A. Return random status codes to confuse attackers
      B. Return only HTTP status codes without any message body
      C. Return success status codes even when errors happen, but include error details in HTML
      D. Return HTTP status codes with clear JSON error messages explaining the problem

      Solution

      1. Step 1: Understand best practices for machine-readable errors

        Machines need both status codes and clear JSON messages to understand errors and automate responses.

      2. Step 2: Evaluate options

        Return HTTP status codes with clear JSON error messages explaining the problem provides both HTTP status codes and JSON messages, which is the recommended approach.

      3. Final Answer:

        Return HTTP status codes with clear JSON error messages explaining the problem -> Option D

      4. Quick Check:

        Status + JSON error message = best practice [OK]
      Hint: Use status codes plus JSON messages for clear machine errors [OK]
      Common Mistakes:
      • Sending no message body with status codes
      • Using success codes for errors
      • Returning HTML instead of JSON for errors