undefined is not an object (evaluating 'allRowsIDs.length') (React-Native)
<p>I'm very new to React-Native. Following the basic React-Native tutorial I'm trying to fetch JSON data from "<a href="https://facebook.github.io/react-native/movies.json" rel="noreferrer">https://facebook.github.io/react-native/movies.json</a>". I can display the <code>title</code> and <code>description</code> properties but when I try to display the "movies" property using a <code>ListView</code> I get the following error:</p>

<blockquote>
  <p>undefined is not an object (evaluating 'allRowsIDs.length')</p>
</blockquote>

<pre><code>import React, { Component } from 'react';
import {
  AppRegistry,
  StyleSheet,
  Text,
  View,
  ListView
} from 'react-native';

var ds = new ListView.DataSource({rowHasChanged: (r1, r2) =&gt; r1 !== r2});

export default class AwesomeProject extends Component {
  constructor(props) {
    super(props);
    this.state = { 
        dataSource: 'init',
    };
  }

  componentWillMount() {
    fetch('https://facebook.github.io/react-native/movies.json')
      .then((response) =&gt; response.json())
      .then((responseJson) =&gt; {
        this.setState({ dataSource: ds.cloneWithRows(responseJson.movies) });
      })
      .catch((error) =&gt; {
        console.error(error);
      });
  }

  render() {
      return (
        &lt;View style={styles.container}&gt;
          &lt;ListView
            dataSource={this.state.dataSource}
            renderRow={(rowData) =&gt; &lt;Text&gt;{rowData}&lt;/Text&gt;}
          /&gt;
        &lt;/View&gt;
      );
  }
}
</code></pre>