我正在尝试将文件及其详细信息保存在数据库中。
有两个调用的瀑布函数，但是第二个函数没有等待第一个函数完成。
即使不使用瀑布，每个系列也无法按预期工作。它不等待记录创建，因此由于相同的ID而发生唯一性错误。 我在这里做错什么，如何解决？
谢谢！
async.eachSeries(uploadedPhotos, async function (uploadedFile, callback) {
async.waterfall([
async function() {
var lastUser = await TblUserFiles.find({}).sort('id DESC').limit(1);
// fileID remains undefined if i remove async-await from the function
var fileID = lastUser[0].id;
fileID += 1;
cbb(null, fileID, uploadedFile);
},
async function(file_id, uploadedFile, cbb) {
sails.log("save file id is " + file_id);
sails.log("savee file id is " + uploadedFile['filename']);
var today = moment(new Date()).format('YYYY-MM-DD HH:mm:ss');
await TblUserFiles.findOrCreate({ customer_no: req.session.userId, file_type: 'profile_image' }, {
id: fileID,
customer_no: req.session.userId,
file_name: uploadedFile['filename'],
file_type: 'profile_image',
is_approved: 'No',
approved_by: 0,
approved_on: today,
approved_from: ip,
uploaded_date: today,
modified_date: today
}).exec(async (err, user, wasCreated) => {
if (err) { return res.serverError(err); }
if (wasCreated) {
// created a new user
sails.log("new file was uploaded...")
return cbb(err, "done");
// return res.send("sent");
}
else {
// found existing user
var user = await TblUserFiles.create({
id: fileID,
customer_no: req.session.userId,
file_name: uploadedFile["filename"],
file_type: "image",
is_approved: "No",
approved_by: 0,
approved_on: today,
approved_from: ip,
uploaded_date: today,
modified_date: today
}).intercept(err => {
// Return a modified error here (or a special exit signal)
// and .create() will throw that instead
err.message = "Uh oh: " + err.message;
return err;
}).fetch();
if (user) {
sails.log("found existing files..")
return cbb(err, "done");
}
sails.log("this should not be called");
}
});
}
], (err, success) => {
if (err) sails.log(err);
return callback(err, 'done')
});
}, function (err) {
// if any of the saves produced an error, err would equal that error
if (err) {
sails.log(err);
} else {
return res.json({
message: uploadedPhotos.length + ' file(s) uploaded successfully!',
files: uploadedPhotos
});
}
});
答案 0 :(得分：2)
更新的答案：
我重写了代码。
我忘记了async.js以不同的方式处理promise。基本上，您不使用callback()。请改用return。如果发生错误，请使用throw new Error(message)。
有关更多信息，请参见here。阅读主题：使用ES2017异步功能。
async.eachSeries(uploadedPhotos, async uploadedFile => {
var lastUser = await TblUserFiles.find({}).sort('id DESC').limit(1);
var fileID = lastUser[0].id;
fileID += 1;
sails.log("save file id is " + file_id);
sails.log("savee file id is " + uploadedFile['filename']);
var today = moment(new Date()).format('YYYY-MM-DD HH:mm:ss');
await TblUserFiles.findOrCreate(
{ customer_no: req.session.userId, file_type: 'profile_image' },
{
id: fileID,
customer_no: req.session.userId,
file_name: uploadedFile['filename'],
file_type: 'profile_image',
is_approved: 'No',
approved_by: 0,
approved_on: today,
approved_from: ip,
uploaded_date: today,
modified_date: today
}
).exec(async (err, user, wasCreated) => {
if (err) throw new Error(err);
if (wasCreated) {
sails.log("new file was uploaded...");
return;
} else {
await TblUserFiles.create({
id: fileID,
customer_no: req.session.userId,
file_name: uploadedFile["filename"],
file_type: "image",
is_approved: "No",
approved_by: 0,
approved_on: today,
approved_from: ip,
uploaded_date: today,
modified_date: today
})
.intercept(err => {
throw new Error("Uh oh: " + err.message);
}).fetch();
if (user) {
sails.log("found existing files..");
return;
} else {
sails.log("this should not be called");
return;
}
}
});
}, err => {
// Don't call res.serverError() or res.json() inside the async loop!
if (err) {
sails.log(err);
res.serverError(err);
}
else {
res.json({
message: uploadedPhotos.length + ' file(s) uploaded successfully!',
files: uploadedPhotos
});
}
});
我认为这里的第一个问题是您忘记给第一个任务一个回调函数（在这种情况下为cbb）。
async.waterfall([
async function(cbb) {
var lastUser = await TblUserFiles.find({}).sort('id DESC').limit(1);
// fileID remains undefined if i remove async-await from the function
var fileID = lastUser[0].id;
fileID += 1;
cbb(null, fileID, uploadedFile);
},
async function(file_id, uploadedFile, cbb) {
...
第二，您不应返回回调。回调是功能而不是承诺。只需正常使用它们即可。
顺便说一句，const async = require('async');不会覆盖async关键字。编译器可以分辨出它们之间的区别。以下脚本示例证明了这一点：
const async = require('async');
let runPromise = (name, timer, success = true) => {
console.log(`${name} starts.`);
return new Promise((resolve, reject) => {
if (success) {
setTimeout(function () {
resolve(`${name} finished after ${timer / 1000} seconds(resolved).`);
}, timer);
} else {
reject(`${name} failed(rejected).`);
}
});
};
async function asyncFunction() {
let txt = await runPromise('A', 1000);
console.log(txt);
}
asyncFunction();