React Router data fetching

async-props-style.js

// Define your components like:
class MyComponent extends React.Component {
  static fetchData = (params) => {
    // return an action here.
  };
  
  /* ... */
}

function fetchComponentData(component, store, params) {
  if (component.fetchData) {
    store.dispatch(component.fetchData(params));
  };
}

export default store => ({
  createRouterContext: (child, { components, params }) => {
    for (const component of components) {
      if (!component) {
        continue;
      }

      if (typeof component === 'object') {
        Object.keys(component).forEach(key => {
          fetchComponentData(component[key], store, params);
        });

        continue;
      }

      fetchComponentData(component, store, params);
    }

    return child;
  },
});

react-router-relay-style.js

// Define your routes like:
const myRoute = (
  <Route
    component={myComponent}
    fetchData={params => /* action */}
  />
);

export default store => ({
  createRouterContext: (child, { routes, params }) => {
    routes
      .map(route => route.fetchData)
      .filter(fetchData => fetchData)
      .forEach(fetchData => store.dispatch(fetchData(params)));

    return child;
  },
});

usage.js

ReactDOM.render(
  <Router
    history={history}
    routes={routes}
    render={applyRouterMiddleware(useFetchData(store))}
  />,
  container
);

Discovered a bug with the above. Here's a more complete resolution:

import React from 'react'

class DispatcherContext extends React.Component {
  _fetchData() {
    const { action, dispatch } = this.props

    dispatch(action())
  }

  // We trigger a fetchData call the first time we're loaded, every time.
  // 
  componentDidMount() { this._fetchData() }

  // If this component is passed different children at any point, we want to
  // trigger another fetchData call.
  // 
  // Just putting a blanket update here tends to lead to infinite loops.
  // 
  componentDidUpdate(previous) {
    const previousName = previous.children.type.displayName
    const currentName = this.props.children.type.displayName

    if (previousName !== currentName) { this._fetchData() }
  }

  // We're a bare wrapper around a component with fetchable actions.
  // 
  render() { return this.props.children }
}

export const dispatcherContext = store => {
  // We want to wrap every component with a fetchData static property. I.E.,
  // fetchables.
  // 
  const renderRouteComponent = child => {
    if (child.type.fetchData) {
      return(
        <DispatcherContext dispatch={ store.dispatch }
                           action={ child.type.fetchData }>
          { child }
        </DispatcherContext>
      )
    }

    return child
  }

  return { renderRouteComponent }
}