如何在 Firebase 存储触发函数中获取公共下载链接:“onFinalize"? [英] How to get public download link within a firebase storage trigger function: "onFinalize"?

问题描述

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

I am writing a firebase cloud function that records the download link of a recentally uploaded file to real-time database:

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

});

object"让我可以访问两个变量selfLink"和mediaLink"，但在浏览器中输入这两个变量时，它们都会返回以下内容:

"object" gives me access to two variables "selfLink" and "mediaLink" but both of them when entered in a browser they return the following:

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

因此，它们不是公共链接.如何在此触发函数中获取公共下载链接?

So, they are not public links. How can I get the public download link within this trigger function?

推荐答案

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

You have to use the asynchronous getSignedUrl() method, see the doc of the Cloud Storage Node.js library: 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:

So the following code should do the trick:

.....
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 Question &回答 firebase 函数成功后获取下载地址将图像保存到 Firebase 云存储.

Note that, in order to use the getSignedUrl() method, you need to initialize the Admin SDK with the credentials for a dedicated service account, see this SO Question & Answer firebase function get download url after successfully save image to firebase cloud storage.

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