Javascript - 异步/等待数据集保存在循环中

Question

我正在创建一个筹款平台，但遇到了一些问题，我认为这些问题是由 for 循环中的 Async/await 引起的。

从概念上讲，假设我有一系列人们 promise 的捐款金额。当代码执行时，它将获取筹款目标并循环捐赠，对任何未收费的捐赠 promise 进行收费，直到 promise 用完或达到筹款目标。然后代码更新我的数据库以显示使用了哪些新的捐赠 promise ，或者有多少 promise 可用，因此将来不会重新收费。该代码单独工作正常，但如果我尝试循环它，则会导致错误。

我认为问题在于，循环的 future 迭代在数据集保存并识别出一些捐赠 promise 已被使用之前开始执行。我想我需要让循环的 future 迭代等待，直到保存先前的迭代？

是否有适当的方法来处理这个问题以及如何完成？

谢谢!

for (let i = 0; i < 2; i++) {
    chargeDonations(proj_sub_id, projItem.price, applications.length, project_fees);
}

function chargeDonations(proj_sub_id, price, quantity, fees) {
    wixData.query("Sponsorships")
    .eq("proj_sub_id", proj_sub_id)
    .ne("allFunds", true)
    .find()
    .then( (results) => {   
        let sponsorships = results.
        let toCharge = (price + fees);

    for (let i = 0; i < sponsorships.length; i++) {
        let amount_charged = sponsorships[i].amountCharged;
        amount_charged = amount_charged || 0;
        let remaining_sponsorship = (sponsorships[i].amount - amount_charged);
        let net_amount = (remaining_sponsorship - calculateFeesStripePhil(remaining_sponsorship, 1));
        let net_toCharge = (toCharge + calculateFeesStripePhil(toCharge));
        let sponsorships_sum = sponsorships.sum("amount");

    if ((toCharge - net_amount) > 0) {
        console.log("Donation Amount" + remaining_sponsorship);
        console.log("Net Amount" + net_amount);
        toCharge -= net_amount;
        console.log("Still to be Charged: " + toCharge);
        sponsorships_sum -= remaining_sponsorship;

    $w("#dataset2").setFilter( wixData.filter()
        .eq("_id", sponsorships[i]._id)) 
        .then( () => {
        $w("#dataset2").setFieldValue('amountCharged', (remaining_sponsorship + amount_charged));
        $w("#dataset2").setFieldValue('allFundsUsed', true);
        console.log("Saved Amount Charged");
        $w("#dataset2").save();
        });

        }
     else {                 
        console.log("Sponsorship Amount " + (toCharge / .921 - 0.3).toFixed(2));
        console.log("Net Amount: " + toCharge);

            $w("#dataset2").setFilter( wixData.filter()
        .eq("_id", sponsorships[i]._id)) 
        .then( () => {
        $w("#dataset2").setFieldValue('amountCharged', (toCharge + amount_charged));                        
        console.log("Saved Amount Charged");
        $w("#dataset2").save();                     
            }); 
        break;
                }
                }

        });

}

Answer 1

是的 - 您的假设是正确的，即在前一个循环迭代完成之前调用下一个循环迭代。 使用 async/await 或 Promise.all(/* array of Promise*/) 应该可以解决这个问题。

我相信正确的方法是这样做:

for (let i = 0; i < 2; i++) {
    await chargeDonations(...);
}

async function chargeDonations(...) {
    ...
}

此外，我会检查WixCode API用于 dataset API 中的哪些函数(例如 save、setFilter...)和 $w API返回一个 Promise 并用 async/await block 包装它。

以下是我试图让您的代码更易于阅读和理解的一些内容:

for (let i = 0; i < 2; i++) {
  await chargeDonations(...);
}

async function filterBySubId(filter){
  /*...*/
}
async function filterBySponsorshipId(filter){
  /*...*/
}

async function chargeDonations(proj_sub_id, price, quantity, fees) {
    const results = await filterBySubId();

    let sponsorships = results;
    let toCharge = (price + fees);

    for (let i = 0; i < sponsorships.length; i++) {
      /* I would also put this block in a function and return values */
      let amount_charged = sponsorships[i].amountCharged;
      amount_charged = amount_charged || 0;
      let remaining_sponsorship = (sponsorships[i].amount - amount_charged);
      let net_amount = (remaining_sponsorship - calculateFeesStripePhil(remaining_sponsorship, 1));
      let net_toCharge = (toCharge + calculateFeesStripePhil(toCharge));
      let sponsorships_sum = sponsorships.sum("amount");
      /* end of calculations block */

      if ((toCharge - net_amount) > 0) {
        console.log("Donation Amount" + remaining_sponsorship);
        console.log("Net Amount" + net_amount);
        toCharge -= net_amount;
        console.log("Still to be Charged: " + toCharge);
        sponsorships_sum -= remaining_sponsorship;

        await filterBySponsorshipId(/* your filter */)

        $w("#dataset2").setFieldValue('amountCharged', (remaining_sponsorship + amount_charged));
        $w("#dataset2").setFieldValue('allFundsUsed', true);
        console.log("Saved Amount Charged");
        await $w("#dataset2").save();

      } else {
        console.log("Sponsorship Amount " + (toCharge / .921 - 0.3).toFixed(2));
        console.log("Net Amount: " + toCharge);

        await filterBySponsorshipId(/* your filter */)
        $w("#dataset2").setFieldValue('amountCharged', (toCharge + amount_charged));
        console.log("Saved Amount Charged");
        await $w("#dataset2").save();
        break;
      }
    }
}

希望它对您有意义并能帮助您， 干杯!