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docs / bad-responses / bad-request

BadRequest

The BadRequest class represents an HTTP error response with status code 400. It is used to standardize "Bad Request" error responses, typically when the client sends malformed or invalid data.

Import

ts

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

Constructor

  • message (required): A descriptive message explaining the error cause.
  • 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 { BadRequest } from "@arkyn/server/badRequest";


// Basic usage - throw the error
throw new BadRequest("Invalid request parameters");


// With cause information
throw new BadRequest("Validation failed", {
    field: "email",
    reason: "Invalid format",
});


// Convert to Response object
const error = new BadRequest("Missing required field: name");
return error.toResponse();


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

Response structure

The response body follows a standardized structure:

json

{
    "name": "BadRequest",
    "message": "Invalid request parameters"
}
This is sent with HTTP status 400, 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": "BadRequest",
    "message": "Validation failed",
    "cause": "{\"field\":\"email\",\"reason\":\"Invalid format\"}"
}

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 invalid input data, missing required fields, malformed JSON, and client-side validation errors.
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