text: /**
   * Copyright 2016, Google, Inc.
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *    http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  'use strict';
  
  const Datastore = require('@google-cloud/datastore');
  
  // Instantiates a client
  const datastore = Datastore();
  
  /**
   * Gets a Datastore key from the kind/key pair in the request.
   *
   * @param {object} requestData Cloud Function request data.
   * @param {string} requestData.key Datastore key string.
   * @param {string} requestData.kind Datastore kind.
   * @returns {object} Datastore key object.
   */
  function getKeyFromRequestData (requestData) {
    if (!requestData.key) {
      throw new Error('Key not provided. Make sure you have a "key" property in your request');
    }
  
    if (!requestData.kind) {
      throw new Error('Kind not provided. Make sure you have a "kind" property in your request');
    }
  
    return datastore.key([requestData.kind, requestData.key]);
  }
  
  /**
   * Creates and/or updates a record.
   *
   * @example
   * gcloud functions call set --data '{"kind":"Task","key":"sampletask1","value":{"description": "Buy milk"}}'
   *
   * @param {object} req Cloud Function request context.
   * @param {object} req.body The request body.
   * @param {string} req.body.kind The Datastore kind of the data to save, e.g. "Task".
   * @param {string} req.body.key Key at which to save the data, e.g. "sampletask1".
   * @param {object} req.body.value Value to save to Cloud Datastore, e.g. {"description":"Buy milk"}
   * @param {object} res Cloud Function response context.
   */
  exports.set = (req, res) => {
    // The value contains a JSON document representing the entity we want to save
    if (!req.body.value) {
      throw new Error('Value not provided. Make sure you have a "value" property in your request');
    }
  
    const key = getKeyFromRequestData(req.body);
    const entity = {
      key: key,
      data: req.body.value
    };
  
    return datastore.save(entity)
      .then(() => res.status(200).send(`Entity ${key.path.join('/')} saved.`))
      .catch((err) => {
        console.error(err);
        res.status(500).send(err.message);
        return Promise.reject(err);
      });
  };
  
  /**
   * Retrieves a record.
   *
   * @example
   * gcloud functions call get --data '{"kind":"Task","key":"sampletask1"}'
   *
   * @param {object} req Cloud Function request context.
   * @param {object} req.body The request body.
   * @param {string} req.body.kind The Datastore kind of the data to retrieve, e.g. "Task".
   * @param {string} req.body.key Key at which to retrieve the data, e.g. "sampletask1".
   * @param {object} res Cloud Function response context.
   */
  exports.get = (req, res) => {
    const key = getKeyFromRequestData(req.body);
  
    return datastore.get(key)
      .then(([entity]) => {
        // The get operation will not fail for a non-existent entity, it just
        // returns an empty dictionary.
        if (!entity) {
          throw new Error(`No entity found for key ${key.path.join('/')}.`);
        }
  
        res.status(200).send(entity);
      })
      .catch((err) => {
        console.error(err);
        res.status(500).send(err.message);
        return Promise.reject(err);
      });
  };
  
  /**
   * Deletes a record.
   *
   * @example
   * gcloud functions call del --data '{"kind":"Task","key":"sampletask1"}'
   *
   * @param {object} req Cloud Function request context.
   * @param {object} req.body The request body.
   * @param {string} req.body.kind The Datastore kind of the data to delete, e.g. "Task".
   * @param {string} req.body.key Key at which to delete data, e.g. "sampletask1".
   * @param {object} res Cloud Function response context.
   */
  exports.del = (req, res) => {
    const key = getKeyFromRequestData(req.body);
  
    // Deletes the entity
    // The delete operation will not fail for a non-existent entity, it just
    // doesn't delete anything
    return datastore.delete(key)
      .then(() => res.status(200).send(`Entity ${key.path.join('/')} deleted.`))
      .catch((err) => {
        console.error(err);
        res.status(500).send(err);
        return Promise.reject(err.message);
      });
  };
  