Saving a value as a string with Flutter Firestore Firebase - firebase

Question

I want to save a value from my Cloud Firestore as a string. I am using Flutter with Dart. I have been able to save it when building the page using MaterialepageRoute:
MaterialPageRoute(
builder: (context) => MainScreen(
currentUserId: firebaseUser.uid,
currentUserGender: document['gender'],
currentUserPreference: document['preference'],
)),
But this isn't an option with all of my pages, so I have to look for something else. I want to get the value from my Firestore Database, and then save it as a string, since I want to:
if (currentUserGender == 'male') {
//then do something
}
I have no idea how to do this, I have thought about using a Class, maybe the "get"-function with Firebase, but none have worked. I am not really sure how to do this, so any help is appreciated. I am able to get the currentUser. Here is a picture of my database:
https://imgur.com/KL7HX6P
Thanks in advance.

Answer 1

A Minimal Example: To fetch a Single Document Fields. Swap Collection & Document name in the code with your Own Names.
import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
class GetUser extends StatefulWidget {
#override
_GetUserState createState() => _GetUserState();
}
class _GetUserState extends State<GetUser> {
Map<String, dynamic> userDetails = {};
Future<Null> getUser() async {
await Firestore.instance
.collection('users') // Your Collections Name
.document('eMAE4XF9cTYS12MpfOuWBW4P2WH3') // Your user Document Name
.get()
.then((val) {
userDetails.addAll(val.data);
}).whenComplete(() {
print('Data Fetched');
setState(() {});
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
RaisedButton(
textColor: Colors.white,
color: Theme.of(context).accentColor,
onPressed: () async {
await getUser();
},
child: Text('Get User Detail from Cloud'),
),
userDetails.length > 0
? Column(
children: <Widget>[
Text('${userDetails['gender']}'),
Text('${userDetails['id']}'),
Text('${userDetails['nickname']}'),
userDetails['gender'] == 'male'
? Text('Its Boy')
: Text('Girl'),
],
)
: Text('No user Data, Please Fetch'),
],
),
),
);
}
}