37 lines
1.2 KiB
JavaScript
37 lines
1.2 KiB
JavaScript
import cds from '@sap/cds'
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export class CatalogService extends cds.ApplicationService { init() {
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const { Books } = cds.entities('sap.capire.bookshop')
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const { ListOfBooks } = this.entities
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// Add some discount for overstocked books
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this.after('each', ListOfBooks, book => {
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if (book.stock > 111) book.title += ` -- 11% discount!`
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})
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// Reduce stock of ordered books if available stock suffices
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this.on('submitOrder', async req => {
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let { book:id, quantity } = req.data
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let book = await SELECT.from (Books, id, b => b.stock)
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// Validate input data
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if (!book) return req.error (404, `Book #${id} doesn't exist`)
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if (quantity < 1) return req.error (400, `quantity has to be 1 or more`)
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if (quantity > book.stock) return req.error (409, `${quantity} exceeds stock for book #${id}`)
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// Reduce stock in database and return updated stock value
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await UPDATE (Books, id) .with ({ stock: book.stock -= quantity })
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return book
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})
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// Emit event when an order has been submitted
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this.after('submitOrder', async (_,req) => {
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let { book, quantity } = req.data
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await this.emit('OrderedBook', { book, quantity, buyer: req.user.id })
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})
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// Delegate requests to the underlying generic service
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return super.init()
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}}
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