next.js/examples/with-redux-observable/README.md

Redux-Observable example

How to use

Using create-next-app

Execute create-next-app with Yarn or npx to bootstrap the example:

npx create-next-app --example with-redux-observable with-redux-observable-app
# or
yarn create next-app --example with-redux-observable with-redux-observable-app

Download manually

Download the example:

curl https://codeload.github.com/zeit/next.js/tar.gz/canary | tar -xz --strip=2 next.js-canary/examples/with-redux-observable
cd with-redux-observable

Install it and run:

npm install
npm run dev
# or
yarn
yarn dev

The idea behind the example

This example is a page that renders information about Star-Wars characters. It fetches new character every 3 seconds having the initial character fetched on a server.

Example also uses redux-logger to log every action.

The main problem with integrating Redux, Redux-Observable and Next.js is probably making initial requests on a server. That's because, the getInitialProps hook runs on the server-side before epics have been made available by just dispatching actions.

However, we can access and execute epics directly. In order to do so, we need to pass them an Observable of an action together with StateObservable and they will return an Observable:

static async getInitialProps({ store, isServer }) {
  const state$ = new StateObservable(new Subject(), store.getState());
  const resultAction = await rootEpic(
    of(actions.fetchCharacter(isServer)),
    state$
  ).toPromise(); // we need to convert Observable to Promise
  store.dispatch(resultAction)};

Note: we are not using AjaxObservable from the rxjs library; as of rxjs v5.5.6, it will not work on both the server- and client-side. Instead we call the default export from universal-rxjs-ajax (as request).

We transform the Observable we get from ajax into a Promise in order to await its resolution. That resolution should be a action (since the epic returns Observables of actions). We immediately dispatch that action to the store.

This server-side solution allows compatibility with Next. It may not be something you wish to emulate. In other situations, calling or awaiting epics directly and passing their result to the store would be an anti-pattern. You should only trigger epics by dispatching actions. This solution may not generalise to resolving more complicated sets of actions.

The layout of the redux related functionality is split between:

- actions (in `redux/actions.js`)
- actionTypes (in `redux/actionTypes.js`)
- epics (in `redux/epics.js`)
- reducer (in `redux/reducer.js`)

and organized in redux/index.js.

Excepting in those manners discussed above, the configuration is similar the configuration found in with-redux example and redux-observable docs.