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const EventEmitter = require('events')
module.exports = class IndexDbController extends EventEmitter {
constructor (opts) {
super()
this.migrations = opts.migrations
this.key = opts.key
this.dbObject = global.indexedDB
this.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
this.IDBKeyRange = global.IDBKeyRange || global.webkitIDBKeyRange || global.msIDBKeyRange;
this.version = opts.version
this.logging = opts.logging
this.initialState = opts.initialState
if (this.logging) this.on('log', logger)
}
// Opens the database connection and returns a promise
open (version = this.version) {
return new Promise((resolve, reject) => {
const dbOpenRequest = this.dbObject.open(this.key, version)
dbOpenRequest.onerror = (event) => {
return reject(event)
}
dbOpenRequest.onsuccess = (event) => {
this.db = dbOpenRequest.result
this.emit('success')
resolve(this.db)
}
dbOpenRequest.onupgradeneeded = (event) => {
this.db = event.target.result
this.db.createObjectStore('dataStore')
}
})
.then((openRequest) => {
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)
})
}
requestObjectStore (key, type = 'readonly') {
return new Promise((resolve, reject) => {
const dbReadWrite = this.db.transaction(key, type)
const dataStore = dbReadWrite.objectStore(key)
resolve(dataStore)
})
}
get (key = 'dataStore') {
return this.requestObjectStore(key)
.then((dataObject)=> {
return new Promise((resolve, reject) => {
const getRequest = dataObject.get(key)
getRequest.onsuccess = (event) => resolve(event.currentTarget.result)
getRequest.onerror = (event) => reject(event)
})
})
}
put (state) {
return this.requestObjectStore('dataStore', 'readwrite')
.then((dataObject)=> {
const putRequest = dataObject.put(state, 'dataStore')
putRequest.onsuccess = (event) => Promise.resolve(event.currentTarget.result)
putRequest.onerror = (event) => Promise.reject(event)
})
}
_add (key, objStore, cb = logger) {
return this.requestObjectStore(key, 'readwrite')
.then((dataObject)=> {
const addRequest = dataObject.add(objStore, key)
addRequest.onsuccess = (event) => Promise.resolve(event.currentTarget.result)
addRequest.onerror = (event) => Promise.reject(event)
})
}
}
function logger (err, ress) {
err ? console.error(`Logger says: ${err}`) : console.dir(`Logger says: ${ress}`)
}
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