URL Params

Consider the following urls:

/repos/rackt/react-router
/repos/facebook/react

These urls would match a route path like this:

/repos/:userName/:repoName

The parts that start with : are url parameters whose values will be parsed out and made available to route components on this.props.params[name].

Adding a Route with Parameters

Lets teach our app how to render screens at /repos/:userName/:repoName.

First we need a component to render at the route, make a new file at modules/Repo.js that looks something like this:

// modules/Repo.js
import React from 'react'

export default React.createClass({
  render() {
    return (
      <div>
        <h2>{this.props.params.repoName}</h2>
      </div>
    )
  }
})

Now open up index.js and add the new route.

// ...
// import Repo
import Repo from './modules/Repo'

render((
  <Router history={hashHistory}>
    <Route path="/" component={App}>
      <Route path="/repos" component={Repos}/>
      {/* add the new route */}
      <Route path="/repos/:userName/:repoName" component={Repo}/>
      <Route path="/about" component={About}/>
    </Route>
  </Router>
), document.getElementById('app'))

Now we can add some links to this new route in Repos.js.

// Repos.js
import { Link } from 'react-router'
// ...
export default React.createClass({
  render() {
    return (
      <div>
        <h2>Repos</h2>

        {/* add some links */}
        <ul>
          <li><Link to="/repos/rackt/react-router">React Router</Link></li>
          <li><Link to="/repos/facebook/react">React</Link></li>
        </ul>

      </div>
    )
  }
})

Now go test your links out. Note that the parameter name in the route path becomes the property name in the component. Both repoName and userName are available on this.props.params of your component. You should probably add some prop types to help others and yourself out later.

Next: More Nesting