存储

Storage is an easy way to store key/value pairs and JSON objects. Storage uses a variety of storage engines underneath, picking the best one available depending on the platform.

When running in a native app context, Storage will prioritize using SQLite, as it's one of the most stable and widely used file-based databases, and avoids some of the pitfalls of things like localstorage and IndexedDB, such as the OS deciding to clear out such data in low disk-space situations.

When running in the web or as a Progressive Web App, Storage will attempt to use IndexedDB, WebSQL, and localstorage, in that order.

使用

First, if you'd like to use SQLite, install the cordova-sqlite-storage plugin:

cordova plugin add cordova-sqlite-storage --save

Next, install the package (comes by default for Ionic 2 apps >= RC.0)

npm install --save @ionic/storage

Next, add it to the imports list in yourNgModuledeclaration (for example, insrc/app.module.ts):

import { IonicStorageModule } from '@ionic/storage';

@NgModule({
  declarations: [
    // ...
  ],
  imports: [
    IonicModule.forRoot(MyApp),
    IonicStorageModule.forRoot()
  ],
  bootstrap: [IonicApp],
  entryComponents: [
    // ...
  ],
  providers: []
})
export class AppModule {}

Finally, inject it into any of your components or pages:

import { Storage } from '@ionic/storage';

export class MyApp {
  constructor(storage: Storage) {

     storage.ready().then(() => {

       // set a key/value
       storage.set('name', 'Max');

       // Or to get a key/value pair
       storage.get('age').then((val) => {
         console.log('Your age is', val);
       })
     });
  }
}

配置 Storage

The Storage engine can be configured both with specific storage engine priorities, or custom configuration options to pass to localForage. See the localForage config docs for possible options:https://github.com/localForage/localForage#configuration

Note: Any custom configurations will be merged with the default configuration

import { IonicStorageModule } from '@ionic/storage';

export function provideStorage() {
  return new Storage({ name: '__mydb' });
}

@NgModule({
  declarations: ...,
  imports: [
    IonicStorageModule.forRoot({ useFactory: provideStorage })
  ],
  bootstrap: ...,
  entryComponents: ...,
   providers: []
})
export class AppModule {}

Instance Members

driver

Get the name of the driver being used.

Returns:

Name of the driver

ready()

Reflect the readiness of the store.

Returns:

Promise that resolves when the store is ready

get(key)

Get the value associated with the given key.

Returns:

Promise that resolves with the value

set(key, value)

Set the value for the given key.

Returns:

Promise that resolves when the value is set

remove(key)

Remove any value associated with this key.

Returns:

Promise that resolves when the value is removed

clear()

Clear the entire key value store. WARNING: HOT!

Returns:

Promise that resolves when the store is cleared

length()

Returns:

Promise that resolves with the number of keys stored.

keys()

Returns:

Promise that resolves with the keys in the store.

forEach(iteratorCallback)

Iterate through each key,value pair.

Returns:

Promise that resolves when the iteration has finished.