Hi i am trying to get the data from my database, in componentDidMount(), it works fine with this :

```
componentDidMount() {
  firebase.database().ref('/users/' + user.uid).once('value').then(function(snapshot) { 
      var valeur = snapshot.val();
      return valeur;
  });
  this.setState({userData:valeur});
}

```

I just want to know how can i assign this data to a variable that can be use outside of this function, i tried setstate and using variable that i declare outside nothing work i get :react native possible unhandled promise rejection (id 0) Typeerror: this.setState is not a function. Thank you