javascript - 如何在Firebase存储触发功能中获取公共(public)下载链接: "onFinalize"?

Question

我正在编写一个firebase云函数，它将最近上传的文件的下载链接记录到实时数据库:

exports.recordImage = functions.storage.object().onFinalize((object) => {

});

“object”使我可以访问两个变量“selfLink”和“mediaLink”，但是当在浏览器中输入它们时，它们都会返回以下内容:

Anonymous caller does not have storage.objects.get access to ... {filename}

因此，它们不是公共(public)链接。如何在此触发函数中获取公共(public)下载链接？

Answer 1

您必须使用异步 getSignedUrl() 方法，请参阅 Cloud Storage Node.js 库的文档:https://cloud.google.com/nodejs/docs/reference/storage/2.0.x/File#getSignedUrl .

所以下面的代码应该可以解决问题:

.....
const defaultStorage = admin.storage();
.....

exports.recordImage = functions.storage.object().onFinalize(object => {    
  const bucket = defaultStorage.bucket();
  const file = bucket.file(object.name);

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

  // Get a signed URL for the file
  return file
    .getSignedUrl(options)
    .then(results => {
      const url = results[0];

      console.log(`The signed url for ${filename} is ${url}.`);
      return true;
    })

});

请注意，为了使用 getSignedUrl() 方法，您需要使用专用服务帐户的凭据初始化 Admin SDK，请参阅此 SO 问题与解答 firebase function get download url after successfully save image to firebase cloud storage .