title: React-native: change text of a button
body: <p>I've got a button "follow" and I would like to change the text when the user clicked on and when the follow is done. Here is my code:</p>
  
  <pre><code> this.state = {
    user: [],
    textValue:'Followwww',
    result: [],
    dataSource: new ListView.DataSource({
      rowHasChanged: (row1, row2) =&gt; row1 !== row2,
    })
  };
  
   follow = (item) =&gt; {
  // logout, once that is complete, return the user to the login screen.
  fire.database().ref('follow').push({
    storeName: item.storeName,
    id_user: this.state.user.uid,
    id_store: item._key,
    follow: '1'
  }).then(function(ref) {
      this.setState({ textValue: "Followed" })
      //alert('Vous êtes désormais abonné à : ' + item.storeName + '         !');
  }).catch(function(error) {
      alert(error);
  });
  }
  
   &lt;RkButton 
     rkType='rounded'
     onPress={() =&gt; this.follow(item)}
     style={styles.primary_button_list}
     contentStyle={styles.primary_button_text_list}&gt;
     {this.state.textValue}
   &lt;/RkButton&gt;
  </code></pre>
  
  <p>And I get this error :</p>
  
  <blockquote>
    <p>TypeError: this.state is not a function. (In 'this.state({textValue: "Followed"})', 'this.setState' is undefined)</p>
  </blockquote>
  
  <p>I'm very new in React and I'd love to understand my mistake.
  Thanks</p>