I am trying to use lokijs in my ionic 2 app. i am able to use lokijs.js. when trying to persist using adapter i am not able to. i ready lokijs-cordova-fs-adapter can be used. but when i refer it in my app as below: getting an error that its not able to locate.
var LokiCordovaFSAdapter = require("./cordova-file-system-adapter");
tried adding it in my index.html and tried creating adapter in my ts file as below:
var adapter = new LokiCordovaFSAdapter({"prefix": "loki"});
getting syntax error in this case. can someone give an example on how to use it?
Ciao, this works on Ionic 2, so step-by-step (I did this inside a service):
Check if both dependencies are installed:
npm install lokijs --save npm install loki-cordova-fs-adapter --save
Declare and import the following (before the class declaration):
declare var require: any; var loki = require('lokijs'); var LokiCordovaFSAdapter = require("loki-cordova-fs-adapter"); var adapter = new LokiCordovaFSAdapter({"prefix": "loki"});
Use the following inside the service class:
db: any; // LokiJS database pandas: any; // our DB's document collection object constructor() { console.log("* inicializando..."); this.db = new loki('pandas.db', { autoload: true, autoloadCallback: function() { console.log("* database loaded...") }, autosave: true, autosaveInterval: 10 * 1000, //every 10 seconds adapter: adapter }); }
Use it (this code is also inside the service class):
load() { let collection = this.db.getCollection('pandas'); if (collection == null) { this.pandas = this.db.addCollection('pandas'); } else { this.pandas = collection; } } pandaKamasutra() { console.log("* Save the pandas..."); for (let i=0; i < 100; i++) this.pandas.insert({ name: 'Panda ' + (i+1), surename: "Whurgh " + i }); } showPandas() { var results = this.pandas.find({}); for (let r of results) console.log(`% id: ${r.$loki}, Panda: ${r.name}`); }
I spent this afternoon solving this, after swimming around both LokiJS and lokijs-cordova-fs-adapter code, I found the 'light' in the Ionic documentation here.
Hope it works for you too. =]
See my post at https://github.com/cosmith/loki-cordova-fs-adapter/issues/15 for how to do this in Ionic2 (reposted here).
I finally have this running in an Ionic2 app (with typescript). Be sure to install the plugin cordova-plugin-file
. Then use the adapter at the bottom like a normal Provider in Ionic2 (I have it installed in /src/lib/loki-cordova-fs-adapter
in my project - named as index.ts
).
For usage, here is an example:
import { Injectable } from '@angular/core'
import { Platform } from 'ionic-angular'
import * as Loki from 'lokijs'
import * as LokiIndexedAdapter from 'lokijs/src/loki-indexed-adapter'
import { LokiCordovaFSAdapter } from 'lib/loki-cordova-fs-adapter'
const DATABASE_NAME: string = 'yourFilename.db.json'
@Injectable()
export class DatabaseProvider {
private lokiOptions: any = {
verbose: true,
autosave: true,
autosaveInterval: 60000,
autoload: true
}
private db: any
public constructor (private platform: Platform, private mobileAdapter: LokiCordovaFSAdapter) {}
public load (successCallback: any): void {
if (this.db) {
successCallback()
} else {
this.db = this.loadDatabase(DATABASE_NAME, successCallback)
}
}
private loadDatabase (databaseName: string, successCallback: any): any {
this.lokiOptions.autoloadCallback = successCallback
if (this.platform.is('cordova')) {
this.lokiOptions.adapter = this.mobileAdapter
} else {
this.lokiOptions.adapter = new LokiIndexedAdapter()
}
return new Loki(databaseName, this.lokiOptions)
}
}
Here is the adapter:
import { Injectable } from '@angular/core'
class LokiCordovaFSAdapterError extends Error {}
// const TAG: string = '[LokiCordovaFSAdapter]'
declare var window: any
declare var cordova: any
@Injectable()
export class LokiCordovaFSAdapter {
private options: any
public constructor () {
this.options = {'prefix': 'loki'}
}
public saveDatabase (dbname: string, dbstring: string, callback: any): any {
// console.log(TAG, 'saving database')
this._getFile(dbname,
(fileEntry) => {
fileEntry.createWriter(
(fileWriter) => {
fileWriter.onwriteend = () => {
if (fileWriter.length === 0) {
const blob: any = this._createBlob(dbstring, 'text/plain')
fileWriter.write(blob)
callback()
}
}
fileWriter.truncate(0)
},
(err) => {
// console.log(TAG, 'error writing file', err)
throw new LokiCordovaFSAdapterError('Unable to write file' + JSON.stringify(err))
}
)
},
(err) => {
// console.log(TAG, 'error getting file', err)
throw new LokiCordovaFSAdapterError('Unable to get file' + JSON.stringify(err))
}
)
}
public loadDatabase (dbname: string, callback: any): void {
// console.log(TAG, 'loading database')
this._getFile(dbname,
(fileEntry) => {
// console.log('got database file')
fileEntry.file((file) => {
const reader: FileReader = new FileReader()
reader.onloadend = (event: any) => {
const contents: any = event.target.result
if (contents.length === 0) {
// console.log(TAG, 'database is empty')
callback(null)
} else {
// console.log('sending back database')
callback(contents)
}
}
reader.readAsText(file)
}, (err) => {
// console.log(TAG, 'error reading file', err)
callback(new LokiCordovaFSAdapterError('Unable to read file' + err.message))
})
},
(err) => {
// console.log(TAG, 'error getting file', err)
callback(new LokiCordovaFSAdapterError('Unable to get file: ' + err.message))
}
)
}
public deleteDatabase (dbname: string, callback: any): void {
window.resolveLocalFileSystemURL(cordova.file.dataDirectory,
(dir) => {
const fileName: string = this.options.prefix + '__' + dbname
dir.getFile(fileName, { create: true },
(fileEntry) => {
fileEntry.remove(
() => {
callback()
},
(err) => {
// console.log(TAG, 'error delete file', err)
throw new LokiCordovaFSAdapterError('Unable delete file' + JSON.stringify(err))
}
)
},
(err) => {
// console.log(TAG, 'error delete database', err)
throw new LokiCordovaFSAdapterError(
'Unable delete database' + JSON.stringify(err)
)
}
)
},
(err) => {
throw new LokiCordovaFSAdapterError(
'Unable to resolve local file system URL' + JSON.stringify(err)
)
}
)
}
private _getFile (name: string, handleSuccess: any, handleError: any): void {
// console.log(TAG, 'Retrieving file: ' + name)
window.resolveLocalFileSystemURL(cordova.file.dataDirectory,
(dir) => {
const fileName: string = this.options.prefix + '__' + name
dir.getFile(fileName, { create: true }, handleSuccess, handleError)
},
(err) => {
throw new LokiCordovaFSAdapterError(
'Unable to resolve local file system URL' + JSON.stringify(err)
)
}
)
}
// adapted from http://stackoverflow.com/questions/15293694/blob-constructor-browser-compatibility
private _createBlob (data: string, datatype: string): any {
let blob: any
try {
blob = new Blob([data], { type: datatype })
} catch (err) {
window.BlobBuilder = window.BlobBuilder ||
window.WebKitBlobBuilder ||
window.MozBlobBuilder ||
window.MSBlobBuilder
if (err.name === 'TypeError' && window.BlobBuilder) {
const bb: MSBlobBuilder = new window.BlobBuilder()
bb.append(data)
blob = bb.getBlob(datatype)
} else if (err.name === 'InvalidStateError') {
// InvalidStateError (tested on FF13 WinXP)
blob = new Blob([data], { type: datatype })
} else {
// We're screwed, blob constructor unsupported entirely
throw new LokiCordovaFSAdapterError(
'Unable to create blob' + JSON.stringify(err)
)
}
}
return blob
}
}
来源:https://stackoverflow.com/questions/42386734/how-to-use-lokijs-cordova-fs-adapter-in-ionic-2