@scuba-squad/acceptable/index.js

Content negotiation middleware for Express and Restify

'use strict';

// include dependencies
const {flatten} = require('underscore');
const mime = require('mime');
const debug = require('debug')('@scuba-squad:acceptable');

const acceptable = (...accept) => {
  debug('build:acceptable(%o)', accept);
  accept = flatten(accept)
    .map((value) => {
      value = `${value}`.trim().toLowerCase();
      const ext = mime.getExtension(value);
      const type = mime.getType(value);

      if (ext) {
        return value;
      } else if (type) {
        return type;
      }

      debug('error:Invalid extension or mime/type of %o', value);

      throw new TypeError('Invalid extension or mime/type provided');
    });

  // empty accept so allow any mime/type
  if (!accept.length) {
    accept.push('*/*');
  }

  debug('build:acceptable mime/type = %o', accept);

  return (req, res, next) => {
    debug('call:acceptable(req, res, next)');

    if (req.accepts(accept)) {
      debug('success:URL %s accepts %s', req.url, req.headers.accept);

      return next();
    }

    const error = new Error();
    error.code = 406;
    error.status = 'Not Acceptable';
    error.message = `The requested document can not be provided as ${req.headers.accept}`;

    debug('error:URL %s does not accept %s', req.url, req.headers.accept);

    return next(error);
  };
};

// export middleware as commonjs module
module.exports = acceptable;