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ES7 multiple async/await functions in parallel execution.
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| //old: productReviews.js - lines 121 - 125 | |
| async function productReviewsByProductAllGet(request, response) { | |
| try { | |
| const { productId } = request.params; | |
| // get all reviews for a product id | |
| const reviews = await productReviewsQuery.selectAllByProductId(productId); | |
| const result = []; | |
| // Loop from beginning of reviews array to reviews | |
| for(let i = 0; i < reviews.length; i++) { | |
| // get the account id from a single review, get the user info tied to account id | |
| const user = await accountsQuery.selectByAccountId(reviews[i].accountId); | |
| // add firstname and lastname to review object | |
| reviews[i].firstName = user.firstName; | |
| reviews[i].lastName = user.lastName; | |
| result.push(reviews[i]); | |
| } | |
| response.status(200).json(result); | |
| } catch (error) { | |
| response.status(200).json({ error: 'No Results' }); | |
| } | |
| } | |
| // refactored: first attempt | |
| async function productReviewsByProductAllGet(request, response) { | |
| try { | |
| const { productId } = request.params; | |
| const reviews = await productReviewsQuery.selectAllByProductId(productId); | |
| /** async functions are generator functions that return a promise. | |
| * Use promise.all to get users in parallel instead of one at a time | |
| */ | |
| const result = await Promise.all(reviews.map(async (review) => { | |
| const {firstName, lastName} = await accountsQuery.selectByAccountId(review.accountId); | |
| return Object.assign({}, review, { firstName, lastName }) | |
| })) | |
| response.status(200).json(result); | |
| } catch (error) { | |
| response.status(200).json({ error: 'No Results' }); | |
| } | |
| } | |
| // Final Solution | |
| async function productReviewsByProductAllGet(request, response) { | |
| try { | |
| const { productId } = request.params; | |
| const reviews = await productReviewsQuery.selectAllByProductId(productId); | |
| const reviewPromises = reviews.map( | |
| (review) => accountsQuery.selectByAccountId(review.accountId) | |
| .then( | |
| ({firstName, lastName}) => Object.assign({}, review, { firstName, lastName }) | |
| ) | |
| .catch (error => null) | |
| ) | |
| const result = await Promise.all(reviewPromises) | |
| response.status(200).json(result); | |
| } catch (error) { | |
| response.status(200).json({ error: 'No Results' }); | |
| } | |
| } |
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I like this solution as well. :) Thanks for sharing!