Error response structure in Rest API - Step-by-Step Execution

Concept Flow - Error response structure

Client sends request

↓

Server processes request

↓

Error occurs?

No→Send success response

Yes↓

Create error response

↓

Send error response to client

This flow shows how a server handles a client request and sends an error response if something goes wrong.

Execution Sample

Rest API

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

This JSON shows a typical error response with code, message, and details.

Execution Table

Step	Action	Condition	Result	Response Sent
1	Receive client request	N/A	Request received	No
2	Process request	N/A	Check resource availability	No
3	Resource found?	No	Prepare error response	No
4	Create error JSON	N/A	{"error":{"code":404,"message":"Resource not found","details":"The requested item does not exist."}}	No
5	Send response	N/A	Error response sent to client	Yes

💡 Error response sent because resource was not found

Variable Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	Final
request	None	Received	Received	Received	Received
resource_found	Undefined	Undefined	False	False	False
error_response	None	None	None	{"error":{"code":404,"message":"Resource not found","details":"The requested item does not exist."}}	{"error":{"code":404,"message":"Resource not found","details":"The requested item does not exist."}}

Key Moments - 2 Insights

Why do we include both 'code' and 'message' in the error response?

The 'code' gives a quick numeric identifier for the error (like 404), while the 'message' explains it in words. This helps both machines and humans understand the problem, as shown in step 4 of the execution_table.

What is the purpose of the 'details' field in the error response?

The 'details' field gives extra information to help the client understand the error better. It is optional but useful for debugging, as seen in the error_response variable in variable_tracker after step 4.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of 'resource_found' after step 3?

A True

B False

C Undefined

D None

💡 Hint

Check the variable_tracker row for 'resource_found' after step 3

At which step is the error JSON created?

A Step 2

B Step 3

C Step 4

D Step 5

💡 Hint

Look at the 'Action' and 'Result' columns in execution_table for step 4

If the resource was found, what would happen instead of sending the error response?

A Send success response

B Send error response anyway

C Ignore the request

D Restart the server

💡 Hint

Refer to the concept_flow where 'Error occurs?' leads to different paths

Concept Snapshot

Error response structure:
- Use a JSON object with an 'error' key
- Include 'code' (number), 'message' (string), and optional 'details'
- Sent when server cannot fulfill request
- Helps client understand what went wrong
- Follow consistent format for easy parsing

Full Transcript

This visual execution shows how a server handles a client request and sends an error response if the requested resource is not found. The server receives the request, checks if the resource exists, and when it does not, creates a JSON error response with code 404, a message, and details. This error response is then sent back to the client. Variables like 'resource_found' and 'error_response' track the state during execution. Key points include why both code and message are included and the role of details. The quiz questions help reinforce understanding of the steps and variables involved.