Question

我需要一个我创建的功能来处理用户发送到我的应用程序的图像。

我需要获取用户发送的图像，调整大小并检查图像是否已更改，以避免该功能再次执行。我看到的示例更改了图像名称，并检查了该名称是否与设置的名称相等，但是在我的情况下，我需要保留图片的原始名称，那么，该怎么办？还是存在解决此问题的更好方法？我的功能代码是：

  import * as functions from 'firebase-functions';

  import * as Storage from '@google-cloud/storage';
  const gcs = new Storage();

  import { tmpdir } from 'os';
  import { join, dirname } from 'path';

  import * as sharp from 'sharp';
  import * as fs from 'fs-extra';

  export const generateThumbs = functions.storage
  .object()
  .onFinalize(async object => {
    const bucket = gcs.bucket(object.bucket);
    const filePath = object.name;
    const fileName = filePath.split('/').pop();
    const bucketDir = dirname(filePath);

    const workingDir = join(tmpdir(), 'thumbs');
    const tmpFilePath = join(workingDir, 'source.png');

    if (!object.contentType.includes('image')) {
      console.log('exiting function');
      return false;
    }

    // 1. Ensure thumbnail dir exists
    await fs.ensureDir(workingDir);

    // 2. Download Source File
    await bucket.file(filePath).download({
      destination: tmpFilePath
    });

    // 3. Resize the images and define an array of upload promises
    const sizes = [64, 128, 256];

    const uploadPromises = sizes.map(async size => {
      const thumbName = `thumb@${size}_${fileName}`;
      const thumbPath = join(workingDir, thumbName);

      // Resize source image
      await sharp(tmpFilePath)
        .resize(size, size)
        .toFile(thumbPath);

      // Upload to GCS
      return bucket.upload(thumbPath, {
        destination: join(bucketDir, thumbName)
      });
    });

    // 4. Run the upload operations
    await Promise.all(uploadPromises);

    // 5. Cleanup remove the tmp/thumbs from the filesystem
    return fs.remove(workingDir);
  });

Answer 1

如果您需要覆盖原始文件，并且希望避免此功能造成无限循环，则可以在将文件上传回Cloud Storage时将custom metadata附加到文件。然后，当对该文件再次调用该函数时，可以检查metadata on the incoming ObjectMetadata object来了解该函数何时应退出紧急状态而无需进行任何其他更改。

使用Firebase云功能检查存储中是否存在映像

1 个答案: