Nested Routes in React Router

Objectives

Describe how React Router allows nesting routes
Explain how to organize routes in a standard React & React Router application

Overview

In the previous lesson, we saw how to have routes dynamically render different components. However, as you may have noticed, each time we rendered one component, our previous component disappeared. In this lesson, we'll see how routes can be used to specify multiple components to render.

Master Detail Without Routes

Have you ever used Apple's Messages app for your Mac? How about Gmail? What about YouTube? All of those apps use some version of a "Master-Detail" interface. This is when there is something pertaining to the entire resource, such as a list of all messages, videos, or emails, and some more detailed display of a specific item or action on another portion of the screen. Clicking on a new item in the list changes which item we have selected.

Nesting

With React-Router, we can make accomplish the master detail pattern by making our components children of each other. Take YouTube for example. Let's pretend that visiting /videos displays a list of videos. Clicking on any video keeps our list of videos on the page, but also displays details on the selected video. This should be updated by the URL - the URL should have changed to /videos/:videoId. The VideoDetail in this case is a 'Nested Component' of '/videos' - it will always have the list rendered before it.

Code Along

Rendering Our List

To begin, let's take a look at our starter code. First, we have a MoviesPage component. This component is responsible for connecting to our store and loading our list of movies. A common pattern in Redux is to refer to these as container components and put them in a containers directory. Here we've named ours MoviesPage - again, a common naming pattern for container components.

// ./src/containers/MoviesPage.js
import React from 'react';
import { connect } from 'react-redux';
import MoviesList from '../components/MoviesList';

const MoviesPage = ({ movies }) => 
  <div>
    <MoviesList movies={movies} />
  </div>;

const mapStateToProps = (state) => {
  return {
    movies: state.movies
  };
}

export default connect(mapStateToProps)(MoviesPage);

We are using the mapStateToProps() function to pull the movies property from our store's state and attach it to the props of this component. As you see, our MoviesPage just renders out a MoviesList component. In this case, our MoviesPage component is purely presentational.

Let's create our MoviesList component to render React Router Links for each movie.

// ./src/components/MoviesList.js
import React from 'react';
import { Link } from 'react-router-dom';

const MoviesList = ({ movies }) => {
  const renderMovies = movies.map(movie => 
    <Link key={movie.id} to={`/movies/${movie.id}`}>{movie.title}</Link>
  );
  
  return (
    <div>
      {renderMovies}
    </div>
  );
};

export default MoviesList;

Linking to the Show

Right now, we're using React Router to display the MoviesPage component when the url is /movies (You can look at the code in /src/containers/App.js). Let's add in our first nested route so that going to '/movies/:movieId' will display details about a given movie using a MoviesShow component.

let's create our MoviesShow component. Later on, we will see that this component will need to connect to the store in order to figure out which Movie it should render, but first let's put it in our containers directory.

Note: Remember, containers are components that are directly connected to the store via the connect function.

// ./src/containers/MoviesShow.js
import React from 'react';

const MoviesShow = props => {
  
  return (
    <div>
      <h3>Movies Show Component!</h3>
    </div>
  );
}

export default MoviesShow;

Next, we need to add a nested route in our src/containers/MoviesPage.js file to display the MovieShow container if that route matches /movies/:movieId

// .src/containers/MoviesPage.js
import React from 'react';
import { Route } from 'react-router-dom';
import { connect } from 'react-redux';
import MoviesList from '../components/MoviesList';
import MovieShow from './MovieShow';

const MoviesPage = ({ match, movies }) => 
  <div>
    <MoviesList movies={movies} />
    <Route path={`${match.url}/:movieId`} component={MovieShow}/>
    <Route exact path={match.url} render={() => (
      <h3>Please select a Movie from the list.</h3>
    )}/>
  </div>;

const mapStateToProps = (state) => {
  return {
    movies: state.movies
  };
}

export default connect(mapStateToProps)(MoviesPage);

With the MoviesPage container we are now adding two Route components. You will notice that we are inheriting match from this.props this is a POJO that contains the current url. so we are able to show stuff depending on what the match.url returns. In the 2nd Route component we are defining a path of ${match.url}/:movieId. This will load the MovieShow component when the url looks something like movies/1.

Lets go ahead and make sure that our MoviesList component has links to get to this nested route.

// ./src/components/MoviesList.js
import React from 'react';
import { Link } from 'react-router-dom';

const MoviesList = ({ movies }) => {
  const renderMovies = movies.map(movie => 
    <Link to={`/movies/${movie.id}`}>{movie.title}</Link>
  );
  
  return (
    <div>
      {renderMovies}
    </div>
  );
};

export default MoviesList;

Awesome! Refresh the page at /movies. Now, clicking a link changes the route, but we're not actually seeing any content about that movie that would be in our MoviesShow page. You should only see the text Movies Show Component!. Don't worry we will work on showing the movie details in the next lesson.

Summary

So far we saw how to set up our nested routes. We do so by making two Route componets. One Route component that renders a component if it is a perfect match with the url or the nested Route if it includes the match.url and the nested key(in this case :movieId).

monacorona/react-router-nested-routes-web-051517