bedrock-web-store

A module for creating shared storage for Bedrock Web Apps. The design requires stored objects to have only one instance in memory. The objects may be backed by a persistent storage layer such as localStorage or IndexedDB. Whether or not persistent storage is used is determined by the underlying engine associated with a particular Store instance.

It is important to note that even if a persistent storage mechanism is used, any objects retrieved from storage via the Store API will have only one in-memory copy, ensuring that frontend components will share the same instance. That is to say that a naive implementation of a Store engine that simply maps the API onto, for example, localForage or localStorage would break this guarantee. There must also be a shared memory layer.

Usage

npm install bedrock-web-store

Simple default singleton storage

The most common setup for a Web App is to use a single instance of shared storage across the application. Namespacing can be achieved via the id parameter.

In setup file:

import {store, MemoryEngine} from 'bedrock-web-store';

store.setEngine({engine: new MemoryEngine()});

In file 1:

import {store} from 'bedrock-web-store';

const foo = {a: 1, b: 2};

store.create({id: '123', object: foo});

In file 2:

import {store} from 'bedrock-web-store';

const foo = store.get({id: '123'});

console.log(foo.a);
// yields "1"

Multiple stores

More complex Web Apps may have a reason for partitioning storage into different instances. This could be done for namespacing purposes where ids would otherwise clash or because different storage engines are needed for different purposes. In this case, the Store class can be imported and multiple instances (potentially with different engines) can be created and managed by the Web App.

In custom myStores.js:

import {Store, MemoryEngine} from 'bedrock-web-store';

export const stores = {};

stores.foos = new Store({engine: new MemoryEngine()});
stores.bars = new Store({engine: new MemoryEngine()});

In file 1:

import {stores} from './myStores.js';

const foo = {a: 1, b: 2};
stores.foos.create({id: '123', object: foo});

// ...

In file 2:

import {stores} from './myStores.js';

const foo = stores.foos.get({id: '123'});
// same `foo` as file 1

// ...

const bar = stores.bars.get({id: '123'});
// `bar` is undefined