traverson/lib/transforms/extract_url.js

Hypermedia API/HATEOAS client for Node.js and the browser

'use strict';

var minilog = require('minilog')
  , log = minilog('traverson')
  , url = require('url');

var errorModule = require('../errors')
  , errors = errorModule.errors
  , createError = errorModule.createError;

/*
 * This transform is meant to be run at the very end of a get/post/put/patch/
 * delete call. It just extracts the last accessed url from the step and calls
 * t.callback with it.
 */
module.exports = function extractDoc(t) {
  log.debug('walker.walk has finished');
  if (t.step.url) {
    return t.callback(null, t.step.url);
  } else if (t.step.doc &&
    // TODO actually this is very HAL specific :-/
    t.step.doc._links &&
    t.step.doc._links.self &&
    t.step.doc._links.self.href) {
    return t.callback(
        null, url.resolve(t.startUrl, t.step.doc._links.self.href));
  } else {
    return t.callback(createError('You requested an URL but the last ' +
        'resource is an embedded resource and has no URL of its own ' +
        '(that is, it has no link with rel=\"self\"', errors.LinkError));
  }
};