Wait for react-promise to resolve before render

You could do something like this to show a Loader until all the info is fetched:

class Map extends Component {
  constructor () {
    super()
    this.state = { wells: [] }
  }

  componentDidMount() {
    this.props.fetchWells()
      .then(res => this.setState({ wells: res.wells }) )
  }

  render () {
    const { wells } = this.state
    return wells.length ? this.renderWells() : (
      <span>Loading wells...</span>
    )
  }
}