Preview

import React, { PropTypes, Component } from 'react';
import { connect } from 'react-redux';
import { Map } from 'immutable';
import CMS from 'netlify-cms';

export default class DynamicPreview extends Component {
  static propTypes = {
    onChange: PropTypes.func.isRequired,
    onAddAsset: PropTypes.func.isRequired,
    onRemoveAsset: PropTypes.func.isRequired,
    getAsset: PropTypes.func.isRequired,
    // value: PropTypes.object,
    field: PropTypes.node,
    forID: PropTypes.string,
    dynamicWidgets: PropTypes.object
  };

  constructor(props) {
    super(props);
    const fieldValue = this.props.value && Map.isMap(this.props.value) ?
      this.props.value.get(this.props.field.get('name')) :
      this.props.value;

    console.log(this.props.value);
  }

  render() {
    const { field, value, forID, onChange, onAddAsset, onRemoveAsset, getAsset, dynamicWidgets } = this.props;

    const name = field.get('name');
    const selectedName = `${ field.get('name') }_selected`;

    const fieldValue = value && Map.isMap(value) ?
      value.get(name) :
      value;
    const fieldValueSelected = value && Map.isMap(value) ?
      value.get(selectedName) :
      value;

    return (
      <div>{(field && field.get('fields')) || null}</div>
    );
  }
}

fieldValueSelected is always a string on a preview element whereas my control it is an object