Flutter: Add Array to Firestore with a Button - arrays

Question

I am working on developing an app and am currently in the account creation part. I want users to tap on buttons, and the text would be added to a Firestore database that I have created.
Currently, my problem is that I am not sure how to go about setting that up. I have repositories and blocs created for other components of the account creation, but I am struggling to figure out how to create buttons that will store the text as an array in Firestore. I have attached an image of what my screen will look like, my Firestore screen, as well as the code of my database repository and the chunk of code I have thus far with creating buttons that will store the text. The code for my button does NOT work, so I was hoping that I could get some help :):
Database Repository:
class DatabaseRepository extends BaseDatabaseRepository {
final FirebaseFirestore _firebaseFirestore = FirebaseFirestore.instance;
#override
Stream<User> getUser(String userId) {
return _firebaseFirestore
.collection('Users')
.doc(userId)
.snapshots()
.map((snap) => User.fromSnapshot(snap));
}
#override
Stream <List<User>> getUsers(
String userId
) {
return _firebaseFirestore
.collection('Users').snapshots().map((snap) {
return snap.docs.map((doc) => User.fromSnapshot(doc)).toList();
});
}
#override
Future<void> updateUserPictures(User user, String imageName) async{
String downloadURL = await StorageRepository().getDownloadURL(user, imageName);
return _firebaseFirestore
.collection('Users')
.doc(user.id)
.update({
'imageUrls': FieldValue.arrayUnion([downloadURL])});
}
#override
Future<void> UpdateUser(User user) async{
return _firebaseFirestore
.collection('Users')
.doc(user.id)
.update(user.toMap())
.then((value) =>
print('User document updated.'));
}
#override
Future<void> createUser(User user) async{
await _firebaseFirestore
.collection('Users')
.doc(user.id)
.set(user.toMap());
}
}
Button code (thus far):
Widget _button (event) => TextButton(
onPressed: () async {
DocumentReference documentReference = FirebaseFirestore.instance.collection('Users').doc();
DocumentSnapshot doc = await documentReference.get();
List Interests = doc.data('Interests');
if (Interests.contains(event == true) ) {}
},
child: Text(event,
style: GoogleFonts.montserrat()));