55 lines
2.1 KiB
JavaScript
55 lines
2.1 KiB
JavaScript
////////////////////////////////////////////////////////////////////////////
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//
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// Mashing up provided and required services...
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//
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module.exports = async()=>{ // called by server.js
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if (!cds.services.AdminService) return //> mocking S4 service only
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// Connect to services we want to mashup below...
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const S4bupa = await cds.connect.to('API_BUSINESS_PARTNER') //> external S4 service
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const admin = await cds.connect.to('AdminService') //> local domain service
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const db = await cds.connect.to('db') //> our primary database
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// Reflect CDS definition of the Suppliers entity
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const { Suppliers } = db.entities
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admin.prepend (()=>{ //> to ensure our .on handlers below go before the default ones
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// Delegate Value Help reads for Suppliers to S4 backend
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admin.on ('READ', 'Suppliers', req => {
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console.log ('>> delegating to S4 service...')
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return S4bupa.run(req.query)
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})
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// Replicate Supplier data when edited Books have suppliers
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admin.on (['CREATE','UPDATE'], 'Books', async ({data:{supplier_ID:ID}}, next) => {
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if (ID) {
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// Using Promise.all(...) to parallelize local write, i.e. next(), and replication
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const [result] = await Promise.all([ next(), (async()=>{
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let replicated = await db.exists (Suppliers,ID)
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if (!replicated) { // initially replicate Supplier info
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let supplier = await S4bupa.read (Suppliers,ID)
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await INSERT(supplier) .into (Suppliers)
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}
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})()])
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return result
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}
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else return next() //> don't forget to pass down the interceptor stack
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})
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})
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// Subscribe to changes in the S4 origin of Suppliers data
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S4bupa.on ('BusinessPartner.Changed', async msg => { //> would be great if we had batch events from S/4
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console.log(">>", msg.event, msg.data)
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const ID = msg.data.BusinessPartner;
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let replicated = await db.exists (Suppliers,ID)
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if (replicated) { // update replicated Supplier info
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let supplier = await S4bupa.read (Suppliers,ID)
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await UPDATE(Suppliers,ID) .with (supplier)
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}
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})
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}
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