How to hydrate server-side parameters with React + Redux

问题

I have a universal React app that is using Redux and React Router. Some of my routes include parameters that, on the client, will trigger an AJAX request to hydrate the data for display. On the server, these requests could be fulfilled synchronously, and rendered on the first request.

The problem I'm running into is this: By the time any lifecycle method (e.g. componentWillMount) is called on a routed component, it's too late to dispatch a Redux action that will be reflected in the first render.

Here is a simplified view of my server-side rendering code:

routes.js

export default getRoutes (store) {
  return (
    <Route path='/' component={App}>
      <Route path='foo' component={FooLayout}>
        <Route path='view/:id' component={FooViewContainer} />
      </Route>
    </Route>
  )
}

server.js

let store = configureStore()
let routes = getRoutes()
let history = createMemoryHistory(req.path)
let location = req.originalUrl
match({ history, routes, location }, (err, redirectLocation, renderProps) => {
  if (redirectLocation) {
    // redirect
  } else if (err) {
    // 500
  } else if (!renderProps) {
    // 404
  } else {
    let bodyMarkup = ReactDOMServer.renderToString(
      <Provider store={store}>
        <RouterContext {...renderProps} />
      </Provider>)
    res.status(200).send('<!DOCTYPE html>' +
      ReactDOMServer.renderToStaticMarkup(<Html body={bodyMarkup} />))
  }
})

When the FooViewContainer component is constructed on the server, its props for the first render will already be fixed. Any action I dispatch to the store will not be reflected in the first call to render(), which means that they won't be reflected in what's delivered on the page request.

The id parameter that React Router passes along isn't, by itself, useful for that first render. I need to synchronously hydrate that value into a proper object. Where should I put this hydration?

One solution would be to put it, inline, inside the render() method, for instances where it's invoked on the server. This seems obviously incorrect to me because 1) it semantically makes no sense, and 2) whatever data it collects wouldn't be properly dispatched to the store.

Another solution which I have seen is to add a static fetchData method to each of the container components in the Router chain. e.g. something like this:

FooViewContainer.js

class FooViewContainer extends React.Component {

  static fetchData (query, params, store, history) {
    store.dispatch(hydrateFoo(loadFooByIdSync(params.id)))
  }

  ...

}

server.js

let { query, params } = renderProps
renderProps.components.forEach(comp => 
  if (comp.WrappedComponent && comp.WrappedComponent.fetchData) {
    comp.WrappedComponent.fetchData(query, params, store, history)
  }
})

I feel there must be better approach than this. Not only does it seem to be fairly inelegant (is .WrappedComponent a dependable interface?), but it also doesn't work with higher-order components. If any of the routed component classes is wrapped by anything other than connect() this will stop working.

What am I missing here?

回答1:

I recently wrote an article around this requirement, but it does require the use of redux-sagas. It does pickup from the point of view of redux-thunks and using this static fetchData/need pattern.

https://medium.com/@navgarcha7891/react-server-side-rendering-with-simple-redux-store-hydration-9f77ab66900a

I think this saga approach is far more cleaner and simpler to reason about but that might just be my opinion :)

回答2:

There doesn't appear to be a more idiomatic way to do this than the fetchData approach I included in my original question. Although it still seems inelegant to me, it has fewer problems than I initially realized:

.WrappedComponent is a stable interface, but the reference isn't needed anyway. The Redux connect function automatically hoists any static methods from the original class into its wrapper.
Any other higher-order component that wraps a Redux-bound container also needs to hoist (or pass through) any static methods.

There may be other considerations I am not seeing, but I've settled on a helper method like this in my server.js file:

function prefetchComponentData (renderProps, store) {
  let { params, components, location } = renderProps
  components.forEach(componentClass => {
    if (componentClass && typeof componentClass.prefetchData === 'function') {
      componentClass.prefetchData({ store, params, location })
    }
  })
}

来源：https://stackoverflow.com/questions/38438748/how-to-hydrate-server-side-parameters-with-react-redux

标签

reactjs

react-router

react-redux

react-router-redux