Files
cloud-cap-samples/suppliers/srv/mashup.js
2021-06-16 16:44:58 +02:00

50 lines
1.8 KiB
JavaScript

////////////////////////////////////////////////////////////////////////////
//
// Mashing up provided and required services...
//
module.exports = async()=>{ // called by server.js
if (!cds.services.AdminService) return //> mocking S4 service only
// Connect to services we want to mashup below...
const S4bupa = await cds.connect.to('API_BUSINESS_PARTNER') //> external S4 service
const admin = await cds.connect.to('AdminService') //> local domain service
const db = await cds.connect.to('db') //> our primary database
// Reflect CDS definition of the Suppliers entity
const { Suppliers } = db.entities
admin.prepend (()=>{ //> to ensure our .on handlers below go before the default ones
// Delegate Value Help reads for Suppliers to S4 backend
admin.on ('READ', 'Suppliers', req => {
console.log ('>> delegating to S4 service...')
return S4bupa.run(req.query)
})
// Replicate Supplier data when edited Books have suppliers
admin.after (['CREATE','UPDATE'], 'Books', async ({supplier_ID:ID}) => {
if (ID) {
let replicated = await db.exists (Suppliers,ID)
if (!replicated) { // initially replicate Supplier info
let supplier = await S4bupa.read (Suppliers,ID)
await INSERT(supplier) .into (Suppliers)
}
}
})
})
// Subscribe to changes in the S4 origin of Suppliers data
S4bupa.on ('BusinessPartner.Changed', async msg => { //> would be great if we had batch events from S/4
console.log(">>", msg.event, msg.data)
const ID = msg.data.BusinessPartner;
let replicated = await db.exists (Suppliers,ID)
if (replicated) { // update replicated Supplier info
let supplier = await S4bupa.read (Suppliers,ID)
await UPDATE(Suppliers,ID) .with (supplier)
}
})
}