我正在尝试基于上传的文件创建缩略图，但是我不确定这是否是实现此目的的正确方法。现在，以下代码将继续创建缩略图。 if (fileName.startsWith(THUMB_PREFIX)) {这是问题所在。
是否有更简单的方法根据此示例创建多个缩略图？ https://github.com/firebase/functions-samples/blob/master/generate-thumbnail/functions/index.js
exports.onFileChange = functions.storage.object()
.onFinalize((object) => {
const sizes = [200, 50];
const timestamp = + new Date();
sizes.forEach((size, index) => {
// File and directory paths.
const filePath = object.name;
const contentType = object.contentType; // This is the image MIME type
const fileDir = path.dirname(filePath);
let fileName = path.basename(filePath);
let newFileName = path.basename(filePath)
let currentThumbURL = '';
const filename = fileName.substr(0, fileName.indexOf('.'));
let fileExtension = fileName.split('.').pop();
fileName = filename + timestamp + '.' + fileExtension;
const thumbFilePath = path.normalize(path.join(fileDir, `${THUMB_PREFIX}-${size}-${fileName}`));
const tempLocalFile = path.join(os.tmpdir(), filePath);
const tempLocalDir = path.dirname(tempLocalFile);
const tempLocalThumbFile = path.join(os.tmpdir(), thumbFilePath);
var folder = fileDir.substr(0, fileDir.indexOf('/'));
if (folder !== 'profile') return null;
if (!contentType.startsWith('image/')) {
console.log('This is not a profile image.');
return null;
}
// if (index === sizes.length - 1) {
// Exit if the image is already a thumbnail.
if (fileName.startsWith(THUMB_PREFIX)) {
console.log('Already a Thumbnail.');
return null;
}
// }
// Cloud Storage files
const bucket = gcs.bucket(object.bucket);
const file = bucket.file(filePath);
const thumbFile = bucket.file(thumbFilePath);
const metadata = {
contentType: contentType,
// To enable Client-side caching you can set the Cache-Control headers here. Uncomment below.
// 'Cache-Control': 'public,max-age=3600',
};
// Create the temp directory where the storage file will be downloaded.
return mkdirp(tempLocalDir).then(() => {
// Download file from bucket.
return file.download({ destination: tempLocalFile });
}).then(() => {
console.log('The file has been downloaded to', tempLocalFile);
// Generate a thumbnail using ImageMagick.
return spawn('convert', [tempLocalFile, '-thumbnail', `${size}x${size}>`, tempLocalThumbFile], { capture: ['stdout', 'stderr'] });
}).then(() => {
console.log('Thumbnail created at', tempLocalThumbFile);
// Uploading the Thumbnail.
return bucket.upload(tempLocalThumbFile, { destination: thumbFilePath, metadata: metadata });
}).then(() => {
console.log('Thumbnail uploaded to Storage at', thumbFilePath);
// Once the image has been uploaded delete the local files to free up disk space.
console.log('Delet tempLocalFile', tempLocalFile)
console.log('Delete tepLocalThumbFile', tempLocalThumbFile)
fs.unlinkSync(tempLocalFile);
fs.unlinkSync(tempLocalThumbFile);
// Get the Signed URLs for the thumbnail and original image.
const config = {
action: 'read',
expires: '03-01-2500',
};
return Promise.all([
thumbFile.getSignedUrl(config),
file.getSignedUrl(config),
]);
}).then((results) => {
const thumbResult = results[0];
const originalResult = results[1];
const thumbFileUrl = thumbResult[0];
const fileUrl = originalResult[0];
// Add the URLs to the Database
...
}).then(() => {
console.log('Thumbnail URLs saved to database. Delete original uploaded image.')
// bucket.file(`/profile/${filename}/${filename}.png`)
// .delete().then(() => console.log('File deleted'))
// .catch(error => console.log(error))
}
).catch(error => console.log(error));
});
});
答案 0 :(得分：0)
从我们上面的评论中看来，您的问题似乎来自以下事实：由于文件名遵循fileName.startsWith(THUMB_PREFIX)模式，因此您无法使用userkey + -size- + timestamp”来检查正确的文件名。
但是，恕我直言，您的代码中还有另一个问题：您使用sizes.forEach((size, index) => {})触发了两次Cloud Function代码。
原始的Cloud Function代码（来自Firebase官方示例）链接了多个异步操作以生成缩略图。原始的Cloud Function代码仅返回一个承诺，该承诺在链的末尾得到解决。
如果要在Cloud Function中执行两次此代码，则应修改承诺链，以便仅返回一个承诺。
您可以按照以下方式进行操作。这只是关于如何复制异步操作以并行处理两个文件的非常初步的提案。可能有很大的空间来简化代码-避免重复-并注意，它根本没有经过测试！）
return mkdirp(tempLocalDir)
.then(() => {
// Download files from bucket.
const promises = [];
promises.push(file_1.download({ destination: tempLocalFile_1 }));
promises.push(file_2.download({ destination: tempLocalFile_2 }));
return Promise.all(promises);
})
.then(() => {
const promises = [];
promises.push(
spawn(
'convert',
[
tempLocalFile,
'-thumbnail',
`${THUMB_MAX_WIDTH_1}x${THUMB_MAX_HEIGHT_1}>`,
tempLocalThumbFile_1
],
{ capture: ['stdout', 'stderr'] }
)
);
promises.push(
spawn(
'convert',
[
tempLocalFile,
'-thumbnail',
`${THUMB_MAX_WIDTH_2}x${THUMB_MAX_HEIGHT_2}>`,
tempLocalThumbFile_2
],
{ capture: ['stdout', 'stderr'] }
)
);
return Promise.all(promises);
})
.then(() => {
//console.log('Thumbnail created at', tempLocalThumbFile);
// Uploading the Thumbnail.
const promises = [];
promises.push(
bucket.upload(tempLocalThumbFile_1, {
destination: thumbFilePath_1,
metadata: metadata
})
);
promises.push(
bucket.upload(tempLocalThumbFile_1, {
destination: thumbFilePath_1,
metadata: metadata
})
);
return Promise.all(promises);
})
.then(() => {
console.log('Thumbnail uploaded to Storage at', thumbFilePath);
// Once the image has been uploaded delete the local files to free up disk space.
fs.unlinkSync(tempLocalFile_1);
fs.unlinkSync(tempLocalThumbFile_1);
fs.unlinkSync(tempLocalFile_2);
fs.unlinkSync(tempLocalThumbFile_2);
// Get the Signed URLs for the thumbnail and original image.
const config = {
action: 'read',
expires: '03-01-2500'
};
return Promise.all([
thumbFile_1.getSignedUrl(config),
file_1.getSignedUrl(config),
thumbFile_2.getSignedUrl(config),
file_2.getSignedUrl(config)
]);
})
.then(results => {....}}
此外，我建议您观看Firebase视频系列中有关“ JavaScript承诺”的3个视频：https://firebase.google.com/docs/functions/video-series/