next.js/examples/with-relay-modern-server-express/lib/RelayProvider.js

import React from 'react'
import PropTypes from 'prop-types'

// Thank you https://github.com/robrichard
// https://github.com/robrichard/relay-context-provider

class RelayProvider extends React.Component {
  getChildContext () {
    return {
      relay: {
        environment: this.props.environment,
        variables: this.props.variables
      }
    }
  }
  render () {
    return this.props.children
  }
}

RelayProvider.childContextTypes = {
  relay: PropTypes.object.isRequired
}

RelayProvider.propTypes = {
  environment: PropTypes.object.isRequired,
  variables: PropTypes.object.isRequired,
  children: PropTypes.node
}

export default RelayProvider