Let’s first create a route that will check if the user is logged in before routing.

Add the following to src/components/AuthenticatedRoute.js.

import React from "react";
import { Route, Redirect } from "react-router-dom";

export default ({ component: C, props: cProps, ...rest }) =>
  <Route
    {...rest}
    render={props =>
      cProps.isAuthenticated
        ? <C {...props} {...cProps} />
        : <Redirect
            to={`/login?redirect=${props.location.pathname}${props.location
              .search}`}
          />}
  />;

This component is similar to the AppliedRoute component that we created in the Add the session to the state chapter. The main difference being that we look at the props that are passed in to check if a user is authenticated. If the user is authenticated, then we simply render the passed in component. And if the user is not authenticated, then we use the Redirect React Router v4 component to redirect the user to the login page. We also pass in the current path to the login page (redirect in the querystring). We will use this later to redirect us back after the user logs in.

We’ll do something similar to ensure that the user is not authenticated.

Add the following to src/components/UnauthenticatedRoute.js.

import React from "react";
import { Route, Redirect } from "react-router-dom";

export default ({ component: C, props: cProps, ...rest }) =>
  <Route
    {...rest}
    render={props =>
      !cProps.isAuthenticated
        ? <C {...props} {...cProps} />
        : <Redirect to="/" />}
  />;

Here we are checking to ensure that the user is not authenticated before we render the component that is passed in. And in the case where the user is authenticated, we use the Redirect component to simply send the user to the homepage.

Next, let’s use these components in our app.