38 lines
1.2 KiB
JavaScript
38 lines
1.2 KiB
JavaScript
const cds = require ('@sap/cds')
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class OrdersService extends cds.ApplicationService {
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/** register custom handlers */
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init(){
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const { OrderItems } = this.entities
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this.before ('UPDATE', 'Orders', async function(req) {
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const { ID, Items } = req.data
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if (Items) for (let { article, amount } of Items) {
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const { amount:before } = await cds.tx(req).run (
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SELECT.one.from (OrderItems, oi => oi.amount) .where ({order_ID:ID, article})
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)
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if (amount != before) this.orderChanged (article, amount-before)
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}
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})
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this.before ('DELETE', 'Orders', async function(req) {
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const { ID } = req.data
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const Items = await cds.tx(req).run (
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SELECT.from (OrderItems, oi => { oi.article, oi.amount }) .where ({order_ID:ID})
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)
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if (Items) for (let it of Items) this.orderChanged (it.article, -it.amount)
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})
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return super.init()
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}
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/** order changed -> broadcast event */
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orderChanged (article, deltaAmount) {
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// Emit events to inform subscribers about changes in orders
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console.log ('> emitting:', 'OrderChanged', { article, deltaAmount })
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return this.emit ('OrderChanged', { article, deltaAmount })
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}
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}
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module.exports = OrdersService
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