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

prisme platform flow engine

/**
 * Created by prisme.io on 09/06/2017.
 */

module.exports = function (RED) {
	/*
	 * Avro Converter Node
	 *
	 * Converts JSON to Avro and Avro to JSON.
	 */
  function avroNode (config) {
    RED.nodes.createNode(this, config)

    var avro = require('avro-js')

    var node = this

    function getPropByString (obj, propString) {
		    if (!propString)		        { return obj }

		    var prop, props = propString.split('.')

		    for (var i = 0, iLen = props.length - 1; i < iLen; i++) {
		        prop = props[i]

		        var candidate = obj[prop]
		        if (candidate !== undefined) {
		            obj = candidate
		        } else {
		            break
		        }
		    }

		    return obj[props[i]]
    }

    function setPropByString (obj, propString, val) {
		    if (!propString)		        { return obj }

		    var prop, props = propString.split('.')

		    for (var i = 0, iLen = props.length - 1; i < iLen; i++) {
		        prop = props[i]

		        var candidate = obj[prop]
		        if (candidate !== undefined) {
		            obj = candidate
		        } else {
		            break
		        }
		    }
		    obj[props[i]] = val
    }

    var schema = ''

    if (config.schemaSelector == 'literal') {
      schema = config.schemaLiteral
    } else if (config.schemaSelector == 'file') {
      schema = config.schemaFile
    } else {
      node.error('Missing schema selector. Must be "literal" or "file".')
    }

    if (!schema) {
      node.error('No Avro schema provided.')
    }

    var type = avro.parse(schema)

    try {
      this.on('input', function (msg) {
        var val = getPropByString(msg, config.property)

        if (typeof (val) === 'undefined') {
          node.error('Property "' + config.property + '" is undefined.')
        }

        if (typeof (val) === 'string') {
          val = JSON.parse(msg[config.property])
        }

        if (typeof (val) === 'object') {
          if (Buffer.isBuffer(val)) {
            val = type.fromBuffer(val)
            setPropByString(msg, config.property, val)
            node.send(msg)
          } else if (type.isValid(val)) {
            val = type.toBuffer(val)
            setPropByString(msg, config.property, val)
            node.send(msg)
          } else {
            node.error(config.property + ' object is not valid for the provided Avro schema: ' + JSON.stringify(val))
          }
        } else {
          node.error(config.property + ' is not an object, type is: ' + typeof (val))
        }
      })
    } catch (e) {
      if (e instanceof SyntaxError) {
        node.error(config.property + ' is neither a JavaScript Object nor a valid JSON string: ' + e)
      } else {
        node.error(e)
      }
    }
  }
  RED.nodes.registerType('avro', avroNode)
}