62 lines
2.4 KiB
JavaScript
62 lines
2.4 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["sap.capire.bookshop.Suppliers"];
|
|
|
|
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.on (['CREATE','UPDATE'], 'Books', async ({data:{supplier_ID: supplierId}}, next) => {
|
|
// Using Promise.all(...) to parallelize local write, i.e. next(), and replication
|
|
|
|
const replicateIfNotExists = async()=>{
|
|
let replicated = await db.exists (Suppliers, supplierId);
|
|
if (!replicated) await replicate (supplierId, 'initial');
|
|
};
|
|
|
|
if (supplierId) {
|
|
const [result, _] = await Promise.all([next(), replicateIfNotExists()]);
|
|
return result;
|
|
} else
|
|
return next(); //> don't forget to pass down the interceptor stack
|
|
})
|
|
|
|
})
|
|
|
|
// 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)
|
|
const ID = msg.data.BusinessPartner;
|
|
let replica = await SELECT.one('ID').from(Suppliers).where({ID});
|
|
if (replica) await replicate(ID);
|
|
})
|
|
|
|
/**
|
|
* Helper function to replicate Suppliers data.
|
|
* @param {string} ID a single ID
|
|
* @param {truthy|falsy} _initial indicates whether an insert or an update is required
|
|
*/
|
|
async function replicate (ID,_initial) {
|
|
let supplier = await S4bupa.run(SELECT.one(Suppliers).where({ID}));
|
|
if (_initial) return db.insert(supplier).into(Suppliers);
|
|
else return db.update(Suppliers).with(supplier).where({ID});
|
|
}
|
|
}
|