29 lines
1.1 KiB
JavaScript
29 lines
1.1 KiB
JavaScript
const cds = require('@sap/cds')
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const { Books } = cds.entities
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/** Service implementation for CatalogService */
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module.exports = cds.service.impl(async function () {
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const bupaSrv = await cds.connect.to('API_BUSINESS_PARTNER')
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this.after('READ', 'Books', each => each.stock > 111 && _addDiscount2(each, 11))
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this.before('CREATE', 'Orders', _reduceStock)
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this.on('READ', 'Addresses', req => bupaSrv.tx(req).run(req.query))
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})
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/** Add some discount for overstocked books */
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function _addDiscount2(each, discount) {
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each.title += ` -- ${discount}% discount!`
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}
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/** Reduce stock of ordered books if available stock suffices */
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async function _reduceStock(req) {
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const { Items: OrderItems } = req.data
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return cds.transaction(req).run(() => OrderItems.map(order =>
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UPDATE(Books).set('stock -=', order.amount)
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.where('ID =', order.book_ID).and('stock >=', order.amount)
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)).then(all => all.forEach((affectedRows, i) => {
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if (affectedRows === 0) req.error(409,
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`${OrderItems[i].amount} exceeds stock for book #${OrderItems[i].book_ID}`
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)
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}))
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}
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