bfx-api-node-models/lib/util/assign_from_collection_or_instance.js

Object models for usage with the Bitfinex node API

'use strict'

const _isArray = require('lodash/isArray')
const _isObject = require('lodash/isObject')

/**
 * Merges provided data onto the target model class, supporting both normal
 * object/array format packets and arrays of them. If given an array of
 * packets, the destination model will become iterable.
 *
 * @param {object} args - arguments
 * @param {object[]|object|Array[]|Array} args.data - data
 * @param {object} [args.fields] - index map in the form { [fieldName]: index }
 * @param {Array} [args.boolFields] - array of boolean field names
 * @param {object} args.target - model class
 */
const assignFromCollectionOrInstance = ({ data, fields, boolFields, target }) => {
  // Use/assign passed in data
  if (!_isArray(data) && _isObject(data)) {
    Object.assign(target, data)
  } else if (_isArray(data) && data.length > 0) {
    // Initialize iterator/setup array-like access if passed an array of models
    let toParse = data

    // Don't make an iterable collection if given an array of 1 item
    if (_isArray(data[0]) && data.length === 1) {
      toParse = data[0]
    }

    if (_isArray(toParse[0]) || _isObject(toParse[0])) {
      const collection = target.constructor.unserialize(toParse)
      target._collection = collection

      Object.assign(target, collection) // needed for [] access
      target.length = collection.length

      target[Symbol.iterator] = function () {
        return {
          _i: -1,
          next: function () {
            this._i++

            return this._i === collection.length
              ? { done: true }
              : { value: collection[this._i], done: false }
          }
        }
      }
    } else {
      Object.assign(target, target.constructor.unserialize(toParse))
    }
  }
}

module.exports = assignFromCollectionOrInstance