Add a practical example

README.md

@@ -9,9 +9,7 @@ A public GraphQL API for information about countries, continents, and languages.
 1. The codes used to key the objects in the original data are available as a `code` property on each item returned from the API.
 2. The `continent` and `languages` properties are now objects and arrays of objects, respectively.
 
-Check out the [playground](https://countries.trevorblades.com) to explore the schema and test out some queries.
+## Writing queries
-
-## Example
 
 ```graphql
 {
@@ -46,3 +44,73 @@ Check out the [playground](https://countries.trevorblades.com) to explore the sc
   }
 }
 ```
+
+Check out the [playground](https://countries.trevorblades.com) to explore the schema and test out some queries.
+
+## Example
+
+A practical use of this API is to create a country select input that doesn't require you to include a large dataset of country info in your bundle.
+
+In this example, we'll be using [React](https://reactjs.org/) and the [Apollo](https://apollographql.com) GraphQL client. First, we'll install all of our dependencies:
+
+```shell
+$ npm install react react-dom react-apollo apollo-boost graphql graphql-tag
+```
+
+50.1 KB with `countries-list`
+14.2 KB with Countries GraphQL
+
+```js
+import React from 'react';
+import ReactDOM from 'react-dom';
+import ApolloClient from 'apollo-boost';
+
+const client = new ApolloClient({
+  uri: 'https://countries.trevorblades.com'
+});
+
+const GET_COUNTRIES = gql`
+  {
+    countries {
+      name
+      code
+    }
+  }
+`;
+
+class App extends Component {
+  state = {
+    country: ''
+  };
+
+  onCountryChange = event =>
+    this.setState({country: event.target.value});
+
+  render() {
+    return (
+      <ApolloProvider client={client}>
+        <Query query={GET_COUNTRIES}>
+          {({loading, error, data}) => {
+            if (loading) return <p>Loading...</p>;
+            if (error) return <p>{error.message}</p>;
+            return (
+              <select
+                value={this.state.country}
+                onChange={this.onCountryChange}
+              >
+                {data.countries.map(country => (
+                  <option key={country.code} value={country.code}>
+                    {country.name}
+                  </option>
+                ))}
+              </select>
+            );
+          }}
+        </Query>
+      </ApolloProvider>
+    );
+  }
+}
+
+ReactDOM.render(<App />, document.getElementById('root'));
+```