Angular Storage

Decorators and services for cookies, session- and localStorage

This library adds decorators that make it super easy to automagically save and restore variables using HTML5's localStorage and sessionStorage. It also provides Angular-Injectable Session- and LocalStorageService.

What's included?

• Decorator functions that are pretty easy to use and configure (see Decorators config):
  • @LocalStorage() - to save variable in HTML5 localStorage
  • @SessionStorage() - to save variable in HTML5 sessionStorage
  • @CookieStorage() - to save variable as a cookie
  • @SharedStorage() - to keep variable in temporary memory that can be shared across classes
• Injectable LocalStorageService, SessionStorageService, CookiesStorageService and SharedStorageService (read more here)
• Availability to listen for storage changes
• Easy configuration (see #configuration section)
• Compatibility with:
  • all previous versions
  • Angular AoT compiler
  • angular2-localstorage
  • nativescript-localstorage
  • your own project!

Upcoming (TODO)

• Tests coverage
• Encoding of saved data
• Handle out of memory cases
• Take configuration from npm config's file (?)
• Automatically handle all data manipulations using Proxy (ES6)

Installation

1. Download the library: npm install ngx-store --save
2. Import the WebStorageModule in your app.module.ts:

   import { NgModule } from '@angular/core';
   import { WebStorageModule } from 'ngx-store';
   
   @NgModule({
     imports: [
       WebStorageModule,
     ],
   })
   export class AppModule {}

Configuration

Things you should take into consideration while configuring this module:

• Decorated objects have added .save() method to easily force save of made changes (configurable by mutateObjects)
• Support for all Array methods that change array object's value can be disabled (configurable by mutateObjects)
• Object mutation can be troublesome for object comparisons, so you can configure this feature for single field passing decorator config
• You may not use prefix (by setting it to ''), however we recommend to use it, as it helps avoid conflicts with other libraries (configurable by prefix)
• There are 3 ways to clear ngx-stored data:
  • 'all' - completely clears current Storage
  • 'prefix' - removes all variables prefixed by ngx-store
  • 'decorators' - removes only variables created by decorating functions (useful when not using prefix) Default behaviour is specified by setting clearType, but it's possible to pass this parameter directly into service clear() method.
• Examples for cookiesScope can be found in this comment

As this project uses decorating functions, it is important to provide custom configuration in global variable named NGXSTORE_CONFIG before Angular application load. Here are some ways to do it:

1. Add <script> in index.html (before Angular sources)

   <script>
   var NGXSTORE_CONFIG = {
     prefix: 'ngx_',      // default: 'ngx_'
     clearType: 'prefix', // default: 'prefix'
     mutateObjects: true, // default: true
     debugMode: false,    // you can enable debug logs if you ever meet any bug to localize its source
     cookiesScope: '',    // what you pass here will actually prepend base domain
     cookiesCheckInterval: 0, // number in ms describing how often cookies should be checked for changes
     previousPrefix: 'angular2ws_', // you have to set it only if you were using custom prefix in old version ('angular2ws_' is a default value)
   };
   </script>

2. If you use webpack, you can provide global variable in your webpack.js file this way:

   plugins: [ 
     new webpack.DefinePlugin({
       NGXSTORE_CONFIG: JSON.stringify({
         prefix: '', // etc
       })
     }),
   ]

Decorators config

Decorating functions can take config object with the following fields:

• key: string - key under the variable will be stored, default key is the variable name
• mutate: boolean - enable or disable object mutation for instance, default depends on global config
• expires: Date - for @CookieStorage() only, specifies expiration date, null = lifetime cookie

Usage

1. Pretty easy to use decorators. Here is where the real magic happens.

   import { CookieStorage, LocalStorage, SessionStorage } from 'ngx-store';
   
   export class MySuperComponent {
     // it will be stored under ${prefix}viewCounts name
     @LocalStorage() viewCounts: number = 0;
     // this under name: ${prefix}differentLocalStorageKey
     @LocalStorage('differentLocalStorageKey') userName: string = '';
     // it will be stored under ${prefix}itWillBeRemovedAfterBrowserClose in session storage
     @SessionStorage({key: 'itWillBeRemovedAfterBrowserClose'}) previousUserNames: Array<string> = [];
     // it will be read from cookie 'user_id' (can be shared with backend) and saved to localStorage and cookies after change
     @LocalStorage() @CookieStorage({prefix: '', key: 'user_id'}) userId: string = '';
     // it will be stored in a cookie named ${prefix}user_workspaces for 24 hours
     @CookieStorage({key: 'user_workspaces', expires: new Date(new Date().getTime() + 24 * 60 * 60 * 1000)}) userWorkspaces = [];
    
     constructor() {
       this.viewCounts++;
       this.userName = 'some name stored in localstorage';
       this.previousUserNames.push(this.userName);
       for (let userName of this.previousUserNames) {
         console.log(userName);
       }
       this.previousUserNames.map(userName => userName.split('').reverse().join(''));
     }
   }

   Sharing variables across classes: Decorated variables can be easily shared across different classes, e.g. Angular Components (also after their destruction) without need to create new service for this purpose.

   import { LocalStorage, SharedStorage } from 'ngx-store';
   
   export class HomeComponent {
     @SharedStorage() title: string = 'Homepage'; // it will be kept in temp memory until app reload
     @LocalStorage() userNote: string = 'Leave your note here'; // it will be read from and saved to localStorage
   
     constructor() {
       setTimeout(() => {
         console.log('userNote:', this.userNote); // it should be changed after user's visit to NestedComponent
       }, 5000);
     }
   }
   
   export class NestedComponent {
     @SharedStorage('title') homeTitle: string = '';
     @LocalStorage() protected userNote: string = '';
   
     constructor() {
       console.log('homeTitle:', this.homeTitle); // should print 'Homepage'
       console.log('userNote:', this.userNote); // should print userNote set in HomeComponent
       this.userNote = "You've visited NestedComponent!";
     }
   }

   Force save changes: If you need to modify stored object by not a direct assignment, then you can take advantage of .save() method to force save made changes. Example:

   import { CookieStorage, LocalStorage, SessionStorage, WebstorableArray } from 'ngx-store';
   
   export class MySuperComponent {
     @LocalStorage() someObject: any = { c: 3 };
     @SessionStorage() arrayOfSomethings: WebstorableArray<number> = <any>[0,1,2,3,4];
     @CookieStorage({ mutate: false }) someCookie: {version?: number, content?: string} = {};
      
     constructor() {
       this.someObject.a = 1;
       this.someObject['b'] = 2;
       delete this.someObject['c'];
       for (let i = 0; i < this.arrayOfSomethings.length; i++) {
         this.arrayOfSomethings[i] += i;
       }
       this.someCookie.version++;
       this.someCookie.content = 'please save me';
       // upper changes won't be saved without the lines below
       this.someObject.save();
       this.arrayOfSomethings.save();
       this.someCookie = this.someCookie; // it looks weird, but also will do the job even without object mutation
      }
   }

   Limited lifecycle classes in AoT compilation: There is a special case when Service or Component in your application containing decorated variable is being destroyed:

   import { OnDestroy } from '@angular/core';
   import { LocalStorage } from 'ngx-store';
   
   export class SomeService implements OnDestroy { // implement the interface
       @LocalStorage() destroyedVariable: any = {};
    
       ngOnDestroy() {} // event empty method is needed to allow ngx-store handle class destruction
   }

2. Use the services to manage your data:

   import { CookiesStorageService, LocalStorageService, SessionStorageService, SharedStorageService } from 'ngx-store';
   
   export class MyService {
     constructor(
       localStorageService: LocalStorageService,
       sessionStorageService: SessionStorageService,
       cookiesStorageService: CookiesStorageService,
       sharedStorageService: SharedStorageService,
     ) {
       console.log('all cookies:');
       cookiesStorageService.utility.forEach((value, key) => console.log(key + '=', value));
     }
   
     public saveSomeData(object: Object, array: Array<any>) {
       this.localStorageService.set('someObject', object);
       this.sessionStorageService.set('someArray', array);
       
       this.localStorageService.keys.forEach((key) => {
         console.log(key + ' =', this.localStorageService.get(key));
       });
     }
   
     public clearSomeData(): void {
       this.localStorageService.clear('decorators'); // removes only variables created by decorating functions
       this.localStorageService.clear('prefix'); // removes variables starting with set prefix (including decorators)
       this.sessionStorageService.clear('all'); // removes all session storage data
     }
   }

Note: Always define default value at the property you are using decorator.

Note: Never use for-in loop on decorated Arrays without filtering by .hasOwnProperty().

Note: Please don't ngx-store circular structures as this library uses JSON.stringify to encode data before saving.

Note: When you change prefix from '' (empty string) old values won't be removed automatically to avoid deleting necessary data. You should handle it manually or set clearType to 'all' for some time.

Contributions are welcome!