不要用承诺工作

Question

我试试这个代码：

function addNewCars(req, res) {
let CarsList = req.body;
carListParsing(carList)
.then(function () {
console.log('OK');
res.status(200).send('OK');
}).catch(function (err) {
res.status(200).send(err);
});
}
function carListParsing (data) {
return new Promise(function (resolve, reject) {
let newCar = {};
newCar.name = data.car_name;
validateCar(newCar).then(function (data) {
console.log('validate result1: ', data); //this line doesn't show 
//if I get validation result, I can use next function createCat()
resolve(data);
}).catch(function (err) {
reject(err);
});
});
}
function validateCar(data) {
db.cars.findAll({where: {name: data.name}}).then(function (org) {
if (org.length < 1) {
console.log('validate1: OK'); //work
return data;
} else {
console.log('validate2: already exist'); //work
return new Error('The ' + data.name + ' car is already exist.');
}
}).catch(function (err) {
return err;
});
}

我想要验证数据=> 汽车名称，如果汽车不存在，则创建新汽车并执行下一个逻辑，例如停车车。如果找到汽车，则执行停车功能。

Answer 1

避免在carListParsing中使用Promise构造函数反模式，并从validateCar中return您的结果承诺！

function addNewCars(req, res) {
// CarsList is a typo
carListParsing(req.body)
.then(function () {
console.log('OK');
res.status(200).send('OK');
}, function (err) { // more appropriate than catch
res.status(200).send(err);
});
}
function carListParsing (data) {
let newCar = {
name: data.car_name
};
// don't call `new Promise`
return validateCar(newCar).then(function (data) {
console.log('validate result1: ', data); //this line doesn't show 
// if I get validation result, I can use next function createCat()
return data; // don't resolve
});
}
function validateCar(data) {
return db.cars.findAll({where: {name: data.name}}).then(function (org) {
//  ^^^^^^
if (org.length < 1) {
console.log('validate1: OK'); //work
return data;
} else {
console.log('validate2: already exist'); //work
throw new Error('The ' + data.name + ' car is already exist.');
//          ^^^^^ probably what you actually wanted
}
}) // don't ignore errors
}