serverEntry.js

import createApp from './main'
import sentryInit from './sentry/server'
import router from './router'

// This exported function will be called by `bundleRenderer`.
// This is where we perform data-prefetching to determine the
// state of our application before actually rendering it.
// Since data fetching is async, this function is expected to
// return a Promise that resolves to the app instance.
export default (context) =>
  new Promise((resolve, reject) => {
    const { app, store } = createApp(router)
    sentryInit()

    const { url } = context
    const { fullPath } = router.resolve(url).route

    if (fullPath !== url) {
      return reject({ url: fullPath })
    }

    // set router's location
    router.push(url)

    // wait until router has resolved possible async hooks
    return router.onReady(() => {
      const matchedComponents = router.getMatchedComponents()
      // no matched routes
      if (!matchedComponents.length) {
        return reject({ code: 404 })
      }
      // Call fetchData hooks on components matched by the route.
      // A preFetch hook dispatches a store action and returns a Promise,
      // which is resolved when the action is complete and store state has been
      // updated.
      return Promise.all(
        matchedComponents.map(
          ({ asyncData }) =>
            asyncData &&
            asyncData({
              store,
              route: router.currentRoute,
            })
        )
      )
        .then(() => {
          // After all preFetch hooks are resolved, our store is now
          // filled with the state needed to render the app.
          // Expose the state on the render context, and let the request handler
          // inline the state in the HTML response. This allows the client-side
          // store to pick-up the server-side state without having to duplicate
          // the initial data fetching on the client.
          // eslint-disable-next-line no-param-reassign
          context.state = store.state
          resolve(app)
        })
        .catch(reject)
    }, reject)
  })