Convert sequelize v4 query response to plain objects preserving all types and associations

lodash.js

const toPlain = response => {
  const flattenDataValues = ({ dataValues }) =>
    _.mapValues(dataValues, value => (
      _.isArray(value) && _.isObject(value[0]) && _.isObject(value[0].dataValues)
        ? _.map(value, flattenDataValues)
        : _.isObject(value) && _.isObject(value.dataValues)
          ? flattenDataValues(value)
          : value
    ));

  return _.isArray(response) ? _.map(response, flattenDataValues) : flattenDataValues(response);
};

plain.js

const toPlain = response => {
  const flattenDataValues = ({ dataValues }) => {
    const flattenedObject = {};

    Object.keys(dataValues).forEach(key => {
      const dataValue = dataValues[key];

      if (
        Array.isArray(dataValue) &&
        dataValue[0] &&
        dataValue[0].dataValues &&
        typeof dataValue[0].dataValues === 'object'
      ) {
        flattenedObject[key] = dataValues[key].map(flattenDataValues);
      } else if (dataValue && dataValue.dataValues && typeof dataValue.dataValues === 'object') {
        flattenedObject[key] = flattenDataValues(dataValues[key]);
      } else {
        flattenedObject[key] = dataValues[key];
      }
    });

    return flattenedObject;
  };

  return Array.isArray(response) ? response.map(flattenDataValues) : flattenDataValues(response);
};

usage.js

const res = await User.findAll({
  include: [{
    model: Company,
    as: 'companies',
    include: [{
      model: Member,
      as: 'member',
    }],
  }],
});

const plain = toPlain(res);

// 'plain' now contains simple db object without any getters/setters with following structure:
// [{
//   id: 123,
//   name: 'John',
//   companies: [{
//     id: 234,
//     name: 'Google',
//     members: [{
//       id: 345,
//       name: 'Paul',
//     }]
//   }]
// }]