const AWS = require("aws-sdk")
const axios = require("axios")
const Promise = require("bluebird")
const { unmarshall } = AWS.DynamoDB.Converter
const STATES = {
CHECKING_CUSTOMER_CARD_AND_CART: 'checkingCustomerCardAndCart',
AWAITING_FULFILLMENT: 'awaitingFulfillment',
AWAITING_PICKUP: 'awaitingPickup',
AWAITING_TIP: 'awaitingTip',
COMPLETED: 'completed',
REFUNDED: 'refunded',
DECLINED: 'declined',
CANCELLED: 'cancelled',
BAD_OR_MISSING_CHARGE_CARD: 'badOrMissingChargeCard',
NONEXISTENT_ITEM_IN_CART: 'nonexistentItemInCart',
}
const usingVersions = (previousVersion, nextVersion) => {
const previousState = previousVersion.state
const nextState = nextVersion.state
return function(targetState) {
return nextState === targetState && previousState !== targetState
}
}
const stateChangedTo = (previousVersion, nextVersion) => {
const previousState = previousVersion.state
const nextState = nextVersion.state
if (nextState !== previousState) {
return nextState
}
}
const actionsByEventName = {
'INSERT': record => {
const newVersion = unmarshall(record.dynamodb.NewImage)
return Event.create('Order', newVersion.id, 'ORDER_CREATED', { order: newVersion })
},
'MODIFY': record => {
const newVersion = unmarshall(record.dynamodb.NewImage)
const oldVersion = unmarshall(record.dynamodb.OldImage)
// Customer tipped AWAITING_TIP -> COMPLETED
const newState = stateChangedTo(oldVersion, newVersion)
if (newState) {
console.log(`changing order ${newVersion.id} to ${newState}`)
}
return Promise.resolve()
},
'REMOVE': Promise.resolve
}
const callback = (err, resp) => {
if (err) {
return console.error(err)
}
console.info(resp)
}
This checks if order records change, if they change, what's the new state.
const response = await axios.get('https://gist.githubusercontent.com/joemocha/4bf44622a4a0a363611ee4e7d120c6b7/raw/830041fe50c8f0889ec3d32db3486273ec56345a/event.orderStreamAwaitingTip.json')
const event = response.data
return Promise.map(event.Records, record => actionsByEventName[record.eventName](record)).
then(() => {
callback(null, `Successfully processed ${event.Records.length} records.`);
}).catch(e => {
if (/Execution Already Exists/.test(e.message)) {
return callback(null, 'Execution Already Exists')
}
console.error(e)
callback(e.message);
})
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