React Native Post Error 'Cannot Load Empty URL'
<p>Trying to make a POST request in React using code below.  To maintain privacy I've deleted the actual parameters and inserted fake ones for the url, accesskey and varArgs variables.  When I try to kick off the request I am getting - 'Error: Cannot load an empty url'. My url variable is a valid string and the post request works fine from curl.  Can anyone see what I am doing wrong?</p>

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

var vsprintf = require('sprintf-js').vsprintf

class plantMetrics extends Component {
  constructor(props){
    super(props)

    const url = 'http://myurl.com'
    const accessKey = 'myaccesskey'
    const varArgs = '{"arg1":"val1"}'

    this.state = {
      catalogMeta: 'shit',
      workspace: '',
      measure: '',
      bu: '',
      country: '',
      plant: '',
      region: ''
    }
  }
    getCatalogInfo(){
    fetch(this.url, {
      method: "POST",
      headers: { 
        'Content-Type': 'application/json',  
        'Authorization': this.accessKey
      },
      body: this.varArgs
    })
    .then((response) =&gt; response.json())
    .then((responseJson) =&gt; {
      this.setState({catalogMeta: JSON.stringify(responseJson.body)})
    })
    .catch((error) =&gt; {      
      this.setState({catalogMeta: 'error: ' + error})
    })
  }

  render() {
    return (
      &lt;View&gt;
        &lt;Text&gt;{"\n"}&lt;/Text&gt;
        &lt;Text&gt;{this.state.catalogMeta}&lt;/Text&gt;
         &lt;TouchableHighlight onPress={this.getCatalogInfo.bind(this)}&gt;
            &lt;Text&gt;Fetch&lt;/Text&gt;
        &lt;/TouchableHighlight&gt;
      &lt;/View&gt;
    );
  }
</code></pre>