Javascript-异步/等待数据集保存在循环中

Question

I'm creating a fundraising platform of sorts, but am running into some issues which I believe are caused by Async/await within for loops.

Conceptually, assume I have an array of donation amounts which people have committed. When the code executes, it will a take fundraising goal and loop through the donations, charging any un-charged donation commitments until the commitments are exhausted or the fundraising goal is met. Then the code updates my database to show which new donation commitments were used, or how much of the commitment is available, so they will not be re-charged in the future. This code individually works fine, but if I try to loop it, it causes errors.

I believe the issue is that the future iterations of the loop start executing before the dataset has saved and recognized that some donation commitments were already used. I think I need to have the future iterations of the loop await until the prior is saved?

Is there a proper way to handle this and how would it be done?

Thanks!

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

YES - you are correct with your assumption that the next loop iteration is called before the previous one has finished. Use of async/await or maybe Promise.all(/* array of promises*/) should solve this issue.

I believe the proper way would be by doing it in this way:

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

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

Furthermore, I would check with WixCode API for which of the functions in the dataset API (eg save , setFilter ...) and $w API return a Promise and wrap that with async/await block.

Here is something I tried to make you code a bit easier to read and understand:

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;
      }
    }
}

Hope it makes sense to you and helps you, Cheers!