Learning_GCP_cloudstorage.js

// Copyright 2017, 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 config = require('../config');

const {Storage} = require("@google-cloud/storage")

const storage = new Storage({
    projectId: config.get('GCLOUD_PROJECT')
})

const GCLOUD_BUCKET = config.get('GCLOUD_BUCKET');
const bucket = storage.bucket(GCLOUD_BUCKET);


// Express middleware that will automatically pass uploads to Cloud Storage.
// req.file is processed and will have a new property:
// * ``cloudStoragePublicUrl`` the public url to the object.
// [START sendUploadToGCS]
function sendUploadToGCS(req, res, next) {
  // The existing code in the handler checks to see if there 
  // is a file property on the HTTP request - if a file has 
  // been uploaded, then Multer will have created this 
  // property in the preceding middleware call.
  if (!req.file) {
    return next();
  }
  // In addition, a unique object name, oname,  has been 
  // created based on the file's original name. It has a 
  // prefix generated using the current date and time.
  // This should ensure that a new file upload won't 
  // overwrite an existing object in the bucket
  const oname = Date.now() + req.file.originalname;

  //reference to the file object.. 
  const file = bucket.file(oname);

  // stream to write the file to google cloud storage
  const stream = file.createWriteStream({
      metadata: {
          contentType: req.file.mimetype,
      }
  });

  stream.on('finish', () => {
      file.makePublic().then(() => {
          req.file.cloudStoragePublicUrl = `https://storage.googleapis.com/${GCLOUD_BUCKET}/${oname}`;
          next();
      })
  });

  stream.on('error', (err) => {
      next(err);
  })

  stream.end(req.file.buffer);

}
// [END sendUploadToGCS]

// Multer handles parsing multipart/form-data requests.
// This instance is configured to store images in memory.
// This makes it straightforward to upload to Cloud Storage.
// [START multer]
const Multer = require('multer');
const multer = Multer({
  storage: Multer.MemoryStorage,
  limits: {
    fileSize: 40 * 1024 * 1024 // no larger than 40mb
  }
});
// [END multer]

module.exports = {
  sendUploadToGCS,
  multer
};