22 lines
645 B
JavaScript
22 lines
645 B
JavaScript
const cds = require('@sap/cds')
|
|
|
|
module.exports = cds.service.impl(function() {
|
|
|
|
const { Books } = cds.entities
|
|
|
|
// Reduce stock of ordered books if available stock suffices
|
|
this.before ('CREATE', 'Orders', (req) => {
|
|
const { Items: items } = req.data
|
|
return cds.transaction(req) .run (items.map (item =>
|
|
UPDATE (Books) .where ('ID =', item.book_ID)
|
|
.and ('stock >=', item.amount)
|
|
.set ('stock -=', item.amount)
|
|
)) .then (all => all.forEach ((affectedRows,i) => {
|
|
if (affectedRows === 0) req.error (409,
|
|
`${items[i].amount} exceeds stock for book #${items[i].book_ID}`
|
|
)
|
|
}))
|
|
})
|
|
|
|
})
|