在存储中获取图片下载网址并将其保存在Firestore中

Question

I am creating a thumbnail from each image I upload to my Firebase Storage. How can I get the downloadURL of the newly created thumbnail image and save it in Firestore?

Thanks for your help.

Path in Firestore:

groups --> groupId --> smallImage

Sample code I use for thumbnail creation:

const functions = require("firebase-functions");
const { Storage } = require('@google-cloud/storage');
const projectId = 'xx'
let gcs = new Storage ({
  projectId
});
const spawn = require("child-process-promise").spawn;
const path = require("path");
const os = require("os");
const fs = require('fs');
// [END import]
// [START generateThumbnail]
// [START generateThumbnailTrigger]
exports.generateThumbnail = functions.storage.object().onFinalize((object) => {
// [END generateThumbnailTrigger]
  // [START eventAttributes]
  const fileBucket = object.bucket; // The Storage bucket that contains the file.
  const filePath = object.name; // File path in the bucket.
  const contentType = object.contentType; // File content type.
  const metageneration = object.metageneration; // Number of times metadata has been generated. New objects have a value of 1.

  const fileName = path.basename(filePath);

  if (fileName.endsWith('_small')) {
    console.log('Already a Thumbnail.');
    return null;
  }
  // [START thumbnailGeneration]
  // Download file from bucket.
  const bucket = gcs.bucket(fileBucket);
  const tempFilePath = path.join(os.tmpdir(), fileName);
  const metadata = {
    contentType: contentType,
  };
  return bucket.file(filePath).download({
    destination: tempFilePath,
  }).then(() => {
    console.log('Image downloaded locally to', tempFilePath);
    // Generate a thumbnail using ImageMagick.
    return spawn('convert', [tempFilePath, '-thumbnail', '200x200>', tempFilePath]);
  }).then(() => {
    console.log('Thumbnail created at', tempFilePath);
    const thumbFileName = path.basename(filePath) + '_small';
    const thumbFilePath = path.join(path.dirname(filePath), thumbFileName);
    // Uploading the thumbnail.
    return bucket.upload(tempFilePath, {
      destination: thumbFilePath,
      metadata: metadata,
    });
    // Once the thumbnail has been uploaded delete the local file to free up disk space.
  }).then(() => fs.unlinkSync(tempFilePath));
  // [END thumbnailGeneration]
});

Answer 1

Yes, your bucket.upload() function can return a File object that you will need:

const options = {destination: thumbFilePath, metadata: metadata};

bucket.upload(tempFilePath, options, function(err, file, apiResp) {

    // `file` is an instance of a File object that refers to your new file.
    const request = require('request');

    const config = {
        action: 'read',
        expires: '03-17-2025'
    };

    file.getSignedUrl(config, function(err, url) {
        if (err) {
            console.error(err);
            return;
        }

        // The file is now available to read from this URL.
        request(url, function(err, resp) {
            // resp.statusCode = 200
        });
    }); 

});

See: https://cloud.google.com/nodejs/docs/reference/storage/2.3.x/File#getSignedUrl