How to implement authenticated routes in React Router 4?

Tnx Tyler McGinnis for solution. I make my idea from Tyler McGinnis idea.

const DecisionRoute = ({ trueComponent, falseComponent, decisionFunc, ...rest }) => {
  return (
    <Route
      {...rest}

      render={
        decisionFunc()
          ? trueComponent
          : falseComponent
      }
    />
  )
}

You can implement that like this

<DecisionRoute path="/signin" exact={true}
            trueComponent={redirectStart}
            falseComponent={SignInPage}
            decisionFunc={isAuth}
          />

decisionFunc just a function that return true or false

const redirectStart = props => <Redirect to="/orders" />

You're going to want to use the Redirect component. There's a few different approaches to this problem. Here's one I like, have a PrivateRoute component that takes in an authed prop and then renders based on that props.

function PrivateRoute ({component: Component, authed, ...rest}) {
  return (
    <Route
      {...rest}
      render={(props) => authed === true
        ? <Component {...props} />
        : <Redirect to={{pathname: '/login', state: {from: props.location}}} />}
    />
  )
}

Now your Routes can look something like this

<Route path='/' exact component={Home} />
<Route path='/login' component={Login} />
<Route path='/register' component={Register} />
<PrivateRoute authed={this.state.authed} path='/dashboard' component={Dashboard} />

If you're still confused, I wrote this post that may help - Protected routes and authentication with React Router v4

All answers are outdated

In 2021 the render prop of the Route component is for legacy use according to the react-router-dom documentation and in my case it wasn't even working (I'm using react-router-dom 5.2.0).

This works instead:

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

const RouteRequiresLogin: FC<React.ComponentProps<typeof Route>> = props => {
   const userIsLogged = useLoginStatus();

   return (
      <Route {...props}>{userIsLogged ? props.children : <LoginPage/>}</Route>
   );
};

export default RouteRequiresLogin;

Usage:

/* A route that requires login */
<RouteRequiresLogin path="/dashboard">
   <DashboardPage />
</RouteRequiresLogin>

/* A route that doesn't require login */
<Route path="/sign-up">
   <SignUpPage />
</Route>