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docs / bad-responses / not-found

NotFound

The NotFound class represents an HTTP error response with status code 404. It is used to standardize "Not Found" error responses, typically when the requested resource does not exist.

Import

ts

import { NotFound } from "@arkyn/server/notFound";
Learn how subpath and root imports differ in How do I use imports.

Constructor

  • message (required): A descriptive message explaining why the resource was not found.
  • cause (optional): Additional information about the error cause, which can be any serializable data.

Methods

toResponse() - Converts the instance into a Response object with JSON body and Content-Type: application/json header.
toJson() - Alternative method using Response.json() for generating the JSON error response.

Usage example

typescript

import { NotFound } from "@arkyn/server/notFound";


// Basic usage - throw the error
throw new NotFound("User not found");


// With cause information
throw new NotFound("Product not found", {
    productId: "abc123",
    searchedIn: "products_table",
});


// Convert to Response object
const error = new NotFound("Order not found");
return error.toResponse();


// Using toJson alternative
return error.toJson();

Response structure

The response body follows a standardized structure:

json

{
    "name": "NotFound",
    "message": "User not found"
}
This is sent with HTTP status 404, set on the Response object itself, the status code is not part of the JSON body.
If a cause is passed to the constructor, it is included in the body as well:

json

{
    "name": "NotFound",
    "message": "Product not found",
    "cause": "{\"productId\":\"abc123\",\"searchedIn\":\"products_table\"}"
}

Notes

When thrown, this class automatically emits a debug log to the console showing the file and function where the error originated. See DebugService to configure ignored files for accurate caller detection.
The cause parameter, when provided, is serialized with JSON.stringify() and included in the response body under the cause key, it is sent to clients, not just kept for server-side debugging. Because it's stringified, cause appears in the JSON body as a JSON-encoded string rather than a nested object.
Common use cases include missing database records, invalid resource IDs, deleted resources, and non-existent API endpoints.
Related in Bad responses
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