Await all promises in the same time in method getEligibleShippingMethods in ShippingCalculator

[jonyw4]

I have some plugins using ShippingCalculator that are promises. Would be nice to all promises were loaded at the same time. Currently, the method getEligibleShippingMethods awaits the response from the shippingMethods individually.

vendure/packages/core/src/service/helpers/shipping-calculator/shipping-calculator.ts

Lines 17 to 32 in b2f3f08

	async getEligibleShippingMethods(
	ctx: RequestContext,
	order: Order,
	): Promise<Array<{ method: ShippingMethod; result: ShippingCalculationResult }>> {
	const shippingMethods = this.shippingMethodService.getActiveShippingMethods(ctx.channel);
	const eligibleMethods: Array<{ method: ShippingMethod; result: ShippingCalculationResult }> = [];
	for (const method of shippingMethods) {
	const eligible = await method.test(order);
	if (eligible) {
	const result = await method.apply(order);
	if (result) {
	eligibleMethods.push({ method, result });
	}
	}
	}
	return eligibleMethods.sort((a, b) => a.result.price - b.result.price);

A solution would be using Promises.all.

[michaelbromley]

Good point, we can parallelize both the test and the apply steps here.

[jonyw4]

I am planning to do a pull request for this issue. Do you have any points before I start to develop?

[michaelbromley]

No, go ahead and make a PR! 👍

[jonyw4]

Good point, we can parallelize both the test and the apply steps here.

To solve the problem I created checkEligibilityByShippingMethod. This function waits for test and apply. So in getEligibleShippingMethods we can make an array of many checkEligibilityByShippingMethod, and then create a Promise.all with everything at the same time.
How apply depends on the response from test I put these two in the same function and apply await for test.

https://github.com/vendure-ecommerce/vendure/pull/407/files#diff-cbb33e9a4b6e3276c9cbe802f7161e80