我正在尝试将多个文件上传到 Google Cloud Storage。我正在为要上传的文件列表中的每个文件使用 for 循环。
但是，问题在于 for 循环在继续下一次上传之前不会暂停以等待上传完成。它最终上传它们，但是，for 循环提前完成，然后将空的urlList.
在继续执行 for 循环中的下一个文件之前，如何让它暂停并等待每个上传过程？
const processFile = require('../middleware');
const { format } = require('util');
let uuidv4 = require('uuid/v4');
const Cloud = require('@google-cloud/storage');
const { Storage } = Cloud;
const storage = new Storage({
keyFilename: './xxx.json',
projectId: 'xxx'
});
const bucket = storage.bucket('xxx');
exports.upload = async (req, res) => {
const urlList = [];
await processFile(req, res); //multer
for (var i = 0; i < req.files.length; i++) {
if (!req.files[i]) {
return res.status(400).send({ message: 'Please upload a file!' });
}
const { originalname, buffer } = req.files[i];
var filename = originalname
.toLowerCase()
.split(' ')
.join('-');
filename = uuidv4() + '-' + filename;
console.log(filename);
const blob = bucket.file(filename);
const blobStream = blob.createWriteStream({
resumable: false
});
blobStream.on('error', err => {
res.status(500).send({ message: err.message });
});
blobStream.on('finish', async data => {
const publicUrl = format(
`https://storage.googleapis.com/${bucket.name}/${blob.name}`
);
urlList.push(publicUrl);
try {
await bucket.file(filename).makePublic();
} catch (err) {
console.log('failed to make it public');
reject(err);
}
});
blobStream.end(buffer);
}
return res.status(200).send({
message: 'Uploaded the files successfully',
url: urlList
});
};
只要把你的“上传”代码的Promise，你可以await在回路中。否则通过使用on其中的代码将不会遵循 for 循环。通过使用这种基于事件的代码，您的 for 循环将通过它而不能等待它完成。这应该可以解决问题：
const uploadFile = (f) => {
return new Promise((resolve, reject) => {
const { originalname, buffer } = f;
var filename = originalname.toLowerCase().split(" ").join("-");
filename = uuidv4() + "-" + filename;
console.log(filename);
const blob = bucket.file(filename);
const blobStream = blob.createWriteStream({
resumable: false,
});
blobStream.on("error", (err) => {
res.status(500).send({ message: err.message });
reject(err);
});
blobStream.on("finish", async (data) => {
const publicUrl = format(
`https://storage.googleapis.com/${bucket.name}/${blob.name}`
);
try {
await bucket.file(filename).makePublic();
resolve(publicUrl);
} catch (err) {
console.log("failed to make it public");
reject(err);
}
});
blobStream.end(buffer);
});
};
exports.upload = async (req, res) => {
const urlList = [];
await processFile(req, res); //multer
for (var i = 0; i < req.files.length; i++) {
if (!req.files[i]) {
return res.status(400).send({ message: "Please upload a file!" });
}
const publicUrl = await uploadFile(req.files[i]);
urlList.push(publicUrl);
}
return res.status(200).send({
message: "Uploaded the files successfully",
url: urlList,
});
};
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