然后执行条件 [英] Conditional .then execution
问题描述
如何有条件地跳过承诺，什么也不做。我创建了一个嵌套的诺言，届时我有7个。但是有条件地，我需要跳过几个.then而在该块中什么也不做，如何实现呢？
How to conditionally skip a promise and do nothing. I have created a nested promise, by which i have 7 .then's. But conditionally, i need to skip few .then and do nothing in that block, how to achive this ?
我的完整代码：
const admin = require('firebase-admin');
const rp = require('request-promise');
module.exports = function(req, res) {
const phone = String(req.body.phone).replace(/[^\d]/g, '');
const amount = parseInt(req.body.amount);
const couponCodeName = (req.body.couponCodeName);
const couponUsage = parseInt(req.body.couponUsage);
const usersCouponUsage = parseInt(req.body.usersCouponUsage);
const finalAddress = (req.body.finalAddress);
const planName = (req.body.planName);
const saveThisAddress = (req.body.saveThisAddress);
const orderNumber = (req.body.orderNumber);
const pay_id = (req.body.pay_id);
const options = {
method: 'POST',
uri:`https://..........`,
body: {
amount
},
json: true
};
return admin.auth().getUser(phone)
.then(userRecord => {
return rp(options)
})
.then((orderResponse) => {
return admin.database().ref('trs/'+ phone)
.push({ pay_id: orderResponse.id })
})
.then(() => {
return admin.database().ref('ors/'+ phone)
.push({ pay_id })
})
.then(() => {
return saveThisAddress === true ?
admin.database().ref('address/'+phone)
.push({address: finalAddress}) : null
})
.then(() => {
return admin.database().ref('deliveryStatus/'+phone+'/'+orderNumber)
.set({ plan: planName === "" ? "Single Day Plan" : planName, delivered: false}, () => {
res.status(200).send({ success:true })
})
})
.then(() => {
return couponCodeName === "" ? null :
admin.database().ref(`couponCodes/${couponCodeName}`)
.update({couponUsage: couponUsage + 1 })
})
.then(() => {
return usersCouponUsage === "" ? null :
admin.database().ref(`couponUsage/${phone}`)
.update({ [couponCodeName]: usersCouponUsage + 1 })
})
.catch((err) => {
res.status(422).send({ error: err })
})
.catch((err) => {
res.status(422).send({error: err });
});
}
从上面的代码中，最后两个。然后有一个条件返回couponCodeName == =？ null：代码...）}。
From the above code, last two .then has a condition return couponCodeName === "" ? null : code... )}.
我需要实现的是，当couponCodeName ===时，它应该跳过.then块而什么也不做。但是，我在此返回null，它引发了未处理的拒绝错误。那么如何实现呢？如何跳过.then，然后什么也不做（重要的是什么都不做，简单地跳过它）。
What i need to achieve is, when the couponCodeName === "" then, it should skip the .then block and do nothing. But, i am returning null in this, it throws an unhandled rejection error. So how to achieve this ? How to skip a .then, and do nothing ( Its important to do nothing, simply skip it ) How to do this ?
我正在得到的错误是：我从这些嵌套中得到的错误是未处理的拒绝和 错误：发送标头后无法设置标头。
THE ERROR I AM GETTING IS: The error i am getting from these nested .then is "Unhandled rejection" & "Error: Can't set headers after they are sent."
来自Google Cloud Function的错误
Error: Can't set headers after they are sent.
at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:369:11)
at ServerResponse.header (/var/tmp/worker/node_modules/express/lib/response.js:767:10)
at ServerResponse.send (/var/tmp/worker/node_modules/express/lib/response.js:170:12)
at ServerResponse.json (/var/tmp/worker/node_modules/express/lib/response.js:267:15)
at ServerResponse.send (/var/tmp/worker/node_modules/express/lib/response.js:158:21)
at admin.auth.getUser.then.then.then.then.then.then.then.catch.catch (/user_code/request_payment_details.js:86:28)
at process._tickDomainCallback (internal/process/next_tick.js:135:7)
还有
Unhandled rejection
注意：Node Js版本：6（因此，我正式认为，我不能使用async和await）
Note: Node Js version : 6 ( So i think officially , i cant use async and await )
推荐答案
也许您可以使用 async / await 为此，因为您需要同步：
Maybe you can use async/await for this, as synchronization is what you need:
async function doSomething() {
var res1 = await promise1();
if (res1 === xxx) {
var res2 = await promise2();
} else {
...
}
}
这篇关于然后执行条件的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
