53 lines
1.8 KiB
JavaScript
53 lines
1.8 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 SAP S4/HANA 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 SAP S4/HANA 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 } = S4bupa.entities
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admin.prepend (()=>{
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// Delegate Value Help reads for Suppliers to SAP S4/HANA backend
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admin.on ('READ', 'Suppliers', async req => {
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console.log ('>> delegating to S4 service...')
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return await S4bupa.run(req.query)
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})
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// Replicate Supplier data when Books are edited
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admin.on (['CREATE','UPDATE'], 'Books', async (req,next) => {
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let { supplier } = req.data
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if (supplier) {
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let cached = await db.exists (Suppliers, supplier)
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if (!cached) await replicate (supplier,'initial')
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}
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return next()
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})
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})
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// Subscribe to changes in the SAP S4/HANA origin of Suppliers data
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S4bupa.on ('BusinessPartner/Changed', async msg => {
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let cached = await SELECT('ID').from (Suppliers)
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.where ('ID in', msg.businessPartner.KEYS)
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for (let each of cached) replicate (each)
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})
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// Helper function to replicate Suppliers data
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async function replicate (ID,_initial) {
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let data = await S4bupa.read (Suppliers, ID)
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if (_initial) return db.insert (data) .into (Suppliers)
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else return db.update (Suppliers,ID) .with (data)
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}
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}
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