83 lines
3.2 KiB
JavaScript
83 lines
3.2 KiB
JavaScript
const cds = require('@sap/cds')
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module.exports = cds.service.impl (async()=>{
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// We are mashing up three services...
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const bupa = await cds.connect.to ('API_BUSINESS_PARTNER')
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const admin = await cds.connect.to ('AdminService')
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const db = await cds.connect.to ('db')
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// Using reflected definitions from connected services/database
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const { Addresses: externalAddresses } = bupa.entities // projection on external addresses
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const { Books, Addresses } = db.entities // entities in local database
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// Delegate ValueHelp requests to S/4 backend, fetching current user's addresses from there
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admin.on ('READ', 'Addresses', (req) => {
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console.log ('Delegating to S/4 bupa service...')
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const UsersAddresses = SELECT.from (externalAddresses) .where ({ contact: req.user.id })
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return bupa.tx(req) .run (UsersAddresses.where (req.query.SELECT.where))
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})
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// Replicate chosen addresses from S/4 when filing orders.
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admin.before ('PATCH', 'Orders', async (req) => {
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const assigned = { ID: req.data.shippingAddress_ID, contact: req.user.id }
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if (!assigned.ID) return //> something else
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const local = db.transaction (req)
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const [replica] = await local.read (Addresses) .where (assigned)
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if (replica) return //> already replicated
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const [address] = await bupa.tx(req) .run (SELECT.from (externalAddresses) .where (assigned))
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if (address) return local.create (Addresses) .entries (address)
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})
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// Subscribe to S/4 event to update local replicas when sources change in S/4.
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bupa.on ('BusinessPartner/Changed', async (msg) => {
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console.log('>> received:', msg.data)
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const BPID = msg.data.KEY[0].BUSINESSPARTNER // TODO: .KEY[0] >> revisit w/ Oliver
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const { SELECT, UPDATE } = cds.ql(msg) //> convenient alternative to <srv>.transaction(req).run(SELECT...)
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// fetch affected entries from local replicas
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const replicas = await SELECT.from (Addresses) .where ({contact:BPID})
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if (replicas.length === 0) return //> not affected
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// fetch changed data from S/4 -> might be less than local due to deletes
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const changed = await SELECT.from (externalAddresses) .where ({
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contact:BPID, ID: replicas.map(a => a.ID) // where in
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})
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// update local replicas with changes from S/4
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const local = db.transaction (msg) //> using that variant to benefit from bulk runs
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return local.run (changed.map (a => UPDATE (Addresses,a.ID) .with (a) ))
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})
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// Validate incoming orders and reduce books' stocks.
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admin.before ('CREATE', 'Orders', async (req) => {
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const { Items } = req.data
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// validate input...
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if (!Items || Items.length === 0)
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return req.reject ('Please order at least one item.')
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if (!req.data.shippingAddress_ID) return req.reject (
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'Please enter a valid shipping address.',
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'shippingAddress_ID'
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)
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// reduce stock on ordered books...
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const all = await db.tx(req) .run (Items.map (each =>
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UPDATE (Books) .where ('ID =', each.book_ID)
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.and ('stock >=', each.amount)
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.set ('stock -=', each.amount)
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))
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all.forEach ((affectedRows,i) => affectedRows > 0 || req.error (409,
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`${Items[i].amount} exceeds stock for book #${Items[i].book_ID}`
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))
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})
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})
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require('./utils') // ugly workaround for AppStudio
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