prisme-flow/nodes/bridge/leveldb/leveldb.js

prisme platform flow engine

/**
 * Created by prisme.io on 09/06/2017.
 */
module.exports = function (RED) {
  'use strict'
  var lvldb = require('level')

  function LevelNode (n) {
    RED.nodes.createNode(this, n)
    this.dbname = n.db
    this.ready = false
    var node = this
    lvldb(this.dbname, function (err, db) {
      if (err) { node.error(err) }
      node.db = db
      node.db.on('ready', function () { node.ready = true })
      node.db.on('closing', function () { node.ready = false })
    })
    node.on('close', function () {
      if (node.db) {
        node.ready = false
        node.db.close()
      }
    })
  }
  RED.nodes.registerType('leveldbase', LevelNode)

  function LevelDBNodeIn (n) {
    RED.nodes.createNode(this, n)
    this.level = n.level
    this.levelConfig = RED.nodes.getNode(this.level)

    var node = this
    node.on('input', function (msg) {
      if (node.levelConfig && node.levelConfig.ready) {
        var key = msg.topic.toString()
        if (key && (key.length > 0)) {
          node.levelConfig.db.get(msg.topic, function (err, value) {
            if (err) {
                            // node.warn(err);
                            // for some reason they treat nothing found as an error...
              msg.payload = null  // so we should return null
            } else { msg.payload = value }
            node.send(msg)
          })
        } else { node.error('Cannot make key string from msg.topic') }
      } else { node.error('Database not ready', msg) }
    })
  }
  RED.nodes.registerType('leveldb in', LevelDBNodeIn)

  function LevelDBNodeOut (n) {
    RED.nodes.createNode(this, n)
    this.level = n.level
    this.operation = n.operation
    this.levelConfig = RED.nodes.getNode(this.level)

    var node = this
    node.on('input', function (msg) {
      if (node.levelConfig && node.levelConfig.ready) {
        var key = msg.topic.toString()
        if (key && (key.length > 0)) {
          if (node.operation === 'delete') {
            node.levelConfig.db.del(msg.topic)
          } else {
            node.levelConfig.db.put(msg.topic, msg.payload, function (err) {
              if (err) { node.error(err, msg) }
            })
          }
        } else { node.error('Cannot make key string from msg.topic', msg) }
      } else { node.error('Database not ready', msg) }
    })
  }
  RED.nodes.registerType('leveldb out', LevelDBNodeOut)
}