wgraph/src/leveldbprops.js

An optionnal thin abstraction layer of LevelGraph

import rsvp from 'rsvp'

class LevelDbProperties {

	constructor(db) {	this.db = db	}

	map(namespace) {
		return new rsvp.Promise((resolve, reject) => {
			this.db.get(namespace, (err, data) => {
				if (err) {
					if (err.message.indexOf('Key not found in database') === -1)
						return reject(err)
				}
				if (!data) data = {}
				else data = JSON.parse(data)
				resolve(data)
			})
		})
	}

	count(namespace) { throw new Error('Not supported operation') }

	get() { 
		let args = arguments
		let nbArgs = args.length
		if (nbArgs < 2)
			throw new Error('Invalid arguments')
		let namespace = args[0]
		delete args[0]
		return this.map(namespace).then(data => {
			let result = {}
			if (nbArgs > 2) {
				for (let i in args) result[args[i]] = data[args[i]]
			} else {
				if (typeof args[1] === 'object')
					args[1].forEach(property => result[property] = data[property])
				else if (typeof args[1] === 'string')
					result = data[args[1]]
				else
					throw new Error('Invalid properties arguments')
			}
			return result
		})
	}

	set() {
		let args = arguments
		let nbArgs = arguments.length
		if (nbArgs < 2 && nbArgs > 3)
			throw new Error('Invalid arguments')
		return new rsvp.Promise((resolve, reject) => {
			this.map(args[0]).then(data => {
				if (nbArgs === 3) {
					data[args[1]] = args[2]
				} else {
					let propsObj = {}
					if (Array.isArray(args[1]))
						args[1].forEach(property => { propsObj[property[0]] = property[1] })
					else if (typeof args[1] === 'object')
						propsObj = args[1]
					else
						return reject(new Error('Invalid properties arguments'));
					for (let property in propsObj) data[property] = propsObj[property]
				}
				this.db.put(args[0], JSON.stringify(data), err => {
					if (err) return reject(err)
					resolve(this)
				})
			})
		})	
	}

	del(namespace, index) {
		return new rsvp.Promise((resolve, reject) => {
			return this.map(namespace).then(data => {
				delete data[index]
				this.db.put(namespace, JSON.stringify(data), err => {
					if (err) return reject(err)
					resolve(this)
				})
			})
		})
	}

	clear(namespace) {
		return new rsvp.Promise((resolve, reject) => {
			this.db.put(namespace, JSON.stringify({}), err => {
				if (err) return reject(err)
				resolve(this)
			})
		})
	}

}

export default LevelDbProperties