Model class with PouchDB

Main.js

export default class User extends Model {
  static className = 'User'
}

await User._put({id: 1, name: 'Jugyo'})
await User.get(1) // {className: "User", id: 1, name: "Jugyo", _id: "User-1", _rev: "1-b2d6c93292974cd1b14a786f7576ec53"}

Model.js

import { EventEmitter } from 'fbemitter'
import PouchDB from 'pouchdb'
import PouchdbAdapterMemory from 'pouchdb-adapter-memory'
import PouchdbFind from 'pouchdb-find'

PouchDB.plugin(PouchdbAdapterMemory);
PouchDB.plugin(PouchdbFind);
const db = new PouchDB('db', {adapter: 'memory'});

db.changes({
  since: 'now',
  live: true,
  include_docs: true, // NOTE: For debug purpose
}).on('change', function (changes) {
  console.log('changes', changes);
}).on('error', function (error) {
  console.log('error', error);
});;

class Model {
  static emitter = new EventEmitter()
  static db = db

  static get(id) {
    return new Promise((resolve, reject) => {
      db.get(this._genId(id)).then((doc) => {
        resolve(doc)
      }).catch(() => {
        resolve(null)
      })
    })
  }

  static _put(newDoc) {
    const id = this._genId(newDoc.id)
    return db.get(id).catch(function (err) {
      if (err.status !== 404) {
        throw err;
      }
      return {};
    }).then((oldDoc) => {
      const doc = this._mergeDoc(oldDoc, newDoc)
      return db.put(doc)
    })
  }

  static _mergeDoc(oldDoc, newDoc) {
    return {
      _id: this._genId(newDoc.id), // NOTE: i.e. User-75 for a user id: 75
      _rev: oldDoc._rev,
      className: this.className,
      ...oldDoc,
      ...newDoc,
    }
  }

  static _merge(docs) {
    return Promise.all((docs || []).map((doc) => this._put(doc)))
  }

  static _update(id, diff) {
    return this.get(id).then((doc) => {
      return this._put({...diff, ...doc})
    })
  }

  static _genId(id) {
    return `${this.className}-${id}`
  }

  static subscribe(callback, event) {
    return this.emitter.addListener(event || 'changed', callback);
  }

  static notify(event) {
    this.emitter.emit(event || 'changed');
  }
}

export default Model