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