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const EventEmitter = require('events')
module.exports = class IndexDbController extends EventEmitter {
constructor (opts) {
super()
global.IDBTransaction = global.IDBTransaction || global.webkitIDBTransaction || global.msIDBTransaction || {READ_WRITE: "readwrite"}; // This line should only be needed if it is needed to support the object's constants for older browsers
global.IDBKeyRange = global.IDBKeyRange || global.webkitIDBKeyRange || global.msIDBKeyRange
this.migrations = opts.migrations
this.key = opts.key
this.version = opts.version
this.initialState = opts.initialState
}
// Opens the database connection and returns a promise
open () {
return this.get('dataStore')
.then((data) => {
if (!data) {
return this._add('dataStore', this.initialState)
.then(() => this.get('dataStore'))
.then((versionedData) => Promise.resolve(versionedData))
}
return Promise.resolve(data)
})
}
get (key = 'dataStore') {
return this._request('get', key)
}
put (state) {
return this._request('put', state, 'dataStore')
}
_add (key = 'dataStore', objStore) {
return this._request('add', objStore, key)
}
_request (call, ...args) {
return new Promise((resolve, reject) => {
const self = this
const dbOpenRequest = global.indexedDB.open(this.key, this.version)
dbOpenRequest.addEventListener('upgradeneeded', (event) => {
this.db = event.target.result
this.db.createObjectStore('dataStore')
})
dbOpenRequest.onsuccess = (event) => {
this.db = dbOpenRequest.result
this.emit('success')
const dbTransaction = this.db.transaction('dataStore', 'readwrite')
const request = dbTransaction.objectStore('dataStore')
const objRequest = request[call](...args)
objRequest.addEventListener('success', (event) => {
return resolve(objRequest.result)
})
objRequest.addEventListener('error', (err) => {
return reject(`IndexDBController - ${call} failed to excute on indexedDB`)
})
dbTransaction.addEventListener('complete', (event) => {
this.emit('complete')
})
}
dbOpenRequest.addEventListener('error', (event) => {
return reject({message: `IndexDBController - open:@${call} failed to excute on indexedDB`, errorEvent: event})
})
})
}
}
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