PERN is a scaffolding tool which makes it easy to build isomorphic apps using Mongo, Express, React and NodeJS. It minimizes the setup time and gets you up to speed using proven technologies.
Note : Please make sure your postgres database is running and cross-env is installed globally before running npm start.
PERN uses Webpack for bundling modules. There are two types of Webpack configs provided webpack.config.dev.js (for development) and webpack.config.prod.js (for production).
The Webpack configuration is minimal and beginner-friendly. You can customize and add more features to it for production build.
PERN uses express web framework. Our app sits in server.js where we check for NODE_ENV.
If NODE_ENV is development we apply Webpack middlewares for bundling and Hot Module Replacement.
We use React Router's match function for handling all page requests so that browser history works.
All the routes are defined in shared/routes.js. React Router renders components according to route requested.
// Server Side Rendering based on routes matched by React-router.
app.use((req, res) => {
match({
routes,
location: req.url
}, (err, redirectLocation, renderProps) => {
if (err) {
return res.status(500).end('Internal server error');
}
if (!renderProps) {
return res.status(404).end('Not found!');
}
const initialState = {
posts: [],
post: {}
};
const store = configureStore(initialState);
fetchComponentData(store.dispatch, renderProps.components, renderProps.params).then(() => {
const initialView = renderToString(
<Provider store = {store} >
<RouterContext {...renderProps}/>
</Provider>
);
const finalState = store.getState();
res.status(200).end(renderFullPage(initialView, finalState));
}).catch(() => {
res.end(renderFullPage('Error', {}));
});
});
});match takes two parameters, first is an object that contains routes, location and history and second is a callback function which is called when routes have been matched to a location.
If there's an error in matching we return 500 status code, if no matches are found we return 404 status code. If a match is found then we need to create a new Redux Store instance.
Note: A new Redux Store is populated afresh on every request.
fetchComponentData is the key function. It takes three params : first is a dispatch function of Redux store, second is an array of components that should be rendered in current route and third is the route params. fetchComponentData collects all the needs (need is an array of actions that are required to be dispatched before rendering the component) of components in the current route. It returns a promise when all the required actions are dispatched. We render the page and send data to client for client-side rendering in window.__INITIAL_STATE__.
Shared directory contains all the components, routes, actions and reducers.
Index.js simply does client side rendering using the data provided from window.__INITIAL_STATE__.
PERN is released under the MIT License.