然后执行条件

Question

如何有条件地不履行诺言而无所作为。我创建了一个嵌套的承诺，到那时我有7个。但是有条件地，我需要跳过几个.then而在那个块中什么也不做，如何实现呢？

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.then有一个条件返回couponCodeName ===“”？null：代码...）}。

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，只需跳过它）。

我得到的错误是：我从这些嵌套的.NET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”。

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)

并且

Unhandled rejection

注意：Node Js版本：6（所以我正式认为，我不能使用async和await）

Answer 1

怎么样

.then(() => {
            return couponCodeName === "" ? null : 
                admin.database().ref(`couponCodes/${couponCodeName}`)
                    .update({couponUsage: couponUsage + 1 })
                .then(() => {
                            admin.database().ref(`couponUsage/${phone}`)
                                .update({ [couponCodeName]: usersCouponUsage + 1 })
                            })}

？