var firebase = require('firebase');

if (!firebase.apps.length) {
    firebase.initializeApp({
        apiKey: "key",
        authDomain: "domain",
        databaseURL: "url",
        storageBucket: "bucket",
    });
}

class Database {
    constructor() {
      this.codesRef = firebase.database().ref('codes');
    }
    isValidCode(text) {
        let codeIsFound = false;
        let identifier = "";
        this.codesRef.once('value', (db_snapshot) => {
          db_snapshot.forEach((code_snapshot) => {
            //console.log(text, code_snapshot.val().value, text == code_snapshot.val().value);
            if (text == code_snapshot.val().value) {
              codeIsFound = true;
              identifier = code_snapshot.key;
            }
          });
          //console.log(codeIsFound); // this is correct
          return codeIsFound; // this always returns undefined
        });
    };
}

module.exports = Database;

import React from 'react';
import {
  StyleSheet,
  View,
  TextInput,
} from 'react-native';

import { withNavigation } from 'react-navigation';

import database from '../Database.js';

const db = new database();


class LoginForm extends React.Component {
  constructor(props) {
    super(props);
  }

  render() {
    return (
      <View style={styles.container}>
        <TextInput
          style={styles.input}
          placeholder="Access Code"
          returnKeyType="go"
          onSubmitEditing={text => {console.log(db.validCode(text.nativeEvent.text))}} // "undefined"
          autoCapitalize="none"
          autoCorrect={false}
        />
      </View>
    );
  }
}

const styles = StyleSheet.create({
  // yay styles :)
});

export default withNavigation(LoginForm);

isValidCode(text) {
    let codeIsFound = false;
    let identifier = "";
    this.codesRef.once('value', (db_snapshot) => {
      db_snapshot.forEach((code_snapshot) => {
        //console.log(text, code_snapshot.val().value, text == code_snapshot.val().value);
        if (text == code_snapshot.val().value) {
          codeIsFound = true;
          identifier = code_snapshot.key;
          takeValue(codeIsFound);
        }
      });
    });
};

takeValue(value){
 console.log(value) //true
}