@sap/cds/lib/srv/middlewares/errors.js

SAP Cloud Application Programming Model - CDS for Node.js

const cds = require('../..')

/**
 * Final error handling middleware, optionally bound to a specific adapter.
 * It handles authentication errors (401) and uncaught system errors, and 
 * normalizes other errors for consistent logging and response formatting.
 * @param {import('../protocols/http')} adapter - The HTTP adapter to bind the error middleware to.
 */
module.exports = exports = adapter => adapter ? http_error.bind(adapter) : http_error

/** 
 * The actual error handling middleware, as used through cds.middlewares.after.
 * @type {import('express').ErrorRequestHandler} 
 * @this {import('../protocols/http')} 
 */
function http_error (error, req, res, next) { // eslint-disable-line no-unused-vars

  if (error == 401 || error.status == 401 || error.code == 401)
    return req._login?.() || res.sendStatus(401)

  // Shutdown on uncaught errors, which could be critical programming errors
  if (!(typeof global.test === 'function') && cds.env.server.shutdown_on_uncaught_errors)
    if (cds.error.isSystemError (error)) 
      return cds.shutdown (error)

  // Log the normalized error
  const { status = 500 } = error, adapter = this.router ? this : dummy
  const log = adapter.logger [status < 500 ? 'warn' : 'error']
  log (status, '-', error)

  // Finalize and send the error response
  if (res.headersSent) return // done by custom code already
  return res.status(status).json(adapter.response4({ error }))
}

// Dummy adapter for compatibility, e.g. with GraphQL adapter
const dummy = new class extends require('../protocols/http') { 
  logger = cds.log('error')
}

// Adjust inspect.depth for better error logging, especially for nested error causes
const { inspect } = require('node:util'); inspect.defaultOptions.depth = 3