Files
cloud-cap-samples/packages/bookshop/srv/admin-service.js
2019-12-19 17:09:29 +01:00

100 lines
4.1 KiB
JavaScript

const cds = require('@sap/cds')
// We are mashing up three services...
const admin = cds.connect.to ('AdminService')
const bupa = cds.connect.to ('API_BUSINESS_PARTNER')
const db = cds.connect.to ('db')
// Using reflected definitions from connected services/database
const { Addresses: externalAddresses } = bupa.entities // projection on external addresses
const { Books, Addresses } = db.entities // entities in local database
module.exports = (admin => {
// Handler to delegate ValueHelp requests to S/4 backend, fetching current user's addresses from there
// admin.on ('READ', 'usersAddresses', (req) => { // REVISIT: all requests go to auto-exposed Addresses
admin.on ('READ', 'Addresses', (req) => {
const { SELECT } = cds.ql(req) //> convenient alternative to bupa.transaction(req).run(SELECT...)
return SELECT.from (externalAddresses) .where ({ contact: req.user.id || 'anonymous' })
//> this is applying projection from CDS model generically, i.e. the equivalent of:
// const { A_BusinessPartnerAddress } = bupa.entities
// return SELECT.from (A_BusinessPartnerAddress, a => {
// a.AddressID.as('ID'),
// a.BusinessPartner,
// a.Country.as('country'),
// a.CityName.as('cityName'),
// a.PostalCode.as('postalCode'),
// a.StreetName.as('streetName'),
// a.HouseNumber.as('houseNumber')
// }) .where ({ BusinessPartner: req.user.id })
})
})
// Replicate chosen addresses from S/4 when filing orders.
admin.before ('PATCH', 'Orders', async (req) => {
const ID = req.data.shippingAddress_ID; if (!ID) return //> something else
const { SELECT, INSERT, UPSERT } = cds.ql(req) //> convenient alternative to <srv>.transaction(req).run(SELECT...)
// const address = await SELECT.one.from (externalAddresses) .where ({ //> TODO
const [address] = await SELECT.from (externalAddresses) .where ({
ID, contact: req.user.id
})
// FIXME: Zweimal INSERT -> constraint violation !!
if (address) return db.tx(req).run (INSERT.into (Addresses) .entries (address))
// if (address) return INSERT.into (Addresses) .entries (address) //> TODO
// if (address) return UPSERT (Addresses) .entries (address) //> TODO
})
// Update local replicas when sources change in S/4.
bupa.on ('BusinessPartner/Changed', async (msg) => {
console.log('>> received:', msg.data)
const BPID = msg.data.KEY[0].BUSINESSPARTNER // TODO: .KEY[0] >> revisit w/ Oliver
const { SELECT, UPDATE } = cds.ql(msg) //> convenient alternative to <srv>.transaction(req).run(SELECT...)
// fetch affected entries from local replicas
const replicas = await SELECT.from (Addresses) .where ({contact:BPID})
if (replicas.length === 0) return //> not affected
// fetch changed data from S/4 -> might be less than local due to deletes
const changed = await SELECT.from (externalAddresses) .where ({
contact:BPID, ID: replicas.map(a => a.ID) // where in
})
// update local replicas with changes from S/4
const local = db.transaction (msg) //> using that variant to benefit from bulk runs
return local.run (changed.map (a => UPDATE (Addresses,a.ID) .with (a) ))
})
// Validate incoming orders and reduce books' stocks.
admin.before ('CREATE', 'Orders', async (req) => {
const { Items } = req.data
// validate input...
if (!Items || Items.length === 0)
return req.reject ('Please order at least one item.')
if (!req.data.shippingAddress_ID) return req.reject (
'Please enter a valid shipping address.',
'shippingAddress_ID'
)
// TODO: future way of doing that:
// const {assert} = req
// assert ('Items') .check (items => items && items.length, 'Please enter at least one order item')
// assert ('shippingAddress') .mandatory() .exists()
// if (req.hasErrors) return
// reduce stock on ordered books...
const all = await db.tx(req) .run (Items.map (each =>
UPDATE (Books) .where ('ID =', each.book_ID)
.and ('stock >=', each.amount)
.set ('stock -=', each.amount)
))
all.forEach ((affectedRows,i) => affectedRows > 0 || req.error (409,
`${Items[i].amount} exceeds stock for book #${Items[i].book_ID}`
))
})