react native get TextInput value

Question

I am stuck with a very simple problem. I have login form with username, password and button. In my button handler, I try to get the textinput value. But always get undefined

Answer 1

Please take care on how to use setState(). The correct form is

this.setState({
      Key: Value,
    });

And so I would do it as follows:

onChangeText={(event) => this.setState({username:event.nativeEvent.text})}
...    
var username=this.state.username;