My flutter code is not reading the code in the order that I expect it to do it

Question

This 3 functions are inside a class, the order in which I use them is the next:

The login Query is called.
If the password matches the username it will call function loginAccepted();
This functions changes the value of a class variable to 1 meaning that the data that was entered is correct.

So far the code works they way. The problem comes now.

I have a ElevatedButton in which I:

Call the loginQuery function from the other class.
If the userMaster.loginVerification is 1 which would mean the data was correct, it will show a popup saying it was correct. (userMaster is the variable that im using to control the functions of that class.)
In case loginVerification is not 1 it will also show a popup saying it.

So then, when i try my code entering a valid username and password it shows this which shows on the left, the console showing in the console the print confirming that the data is a valid user, but then on the right the program shows the popup as if the data I entered is not a valid user.

Then I type in the console userMaster.loginVerification to check whats happening and it shows a 1 which would mean the data I entered was valid but the popup got a 0 for that value which makes no sense.

I don't understand what is happening on my code, I am starting to believe that the functions are the last thing to get executed inside of a ElevatedButton or something, any help would be appreciated.

score 1 · Accepted Answer · answered Apr 26 '21 at 12:08

1

This is effectively this question but that is geared towards JS and you'll be confused. It's just async programming in general though.

Make loginQuery return a Future

Future<void> loginQuery() async {
  var docs = await Firestore.instance.collection(...).where(...).getDocuments();
  // existing if statement
  if(docs.documents.isEmpty) {
   ...
  } else {
   ...
  }
}

await the Future in your onPressed

onPressed:() async {
  await userMaster.loginQuery(...);
  // now do your if check
}

answered Apr 26 '21 at 12:08

Adam Jenkins

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I added the async thing that you suggested but it still didnt work, it actually has the exact same outcome, console shows that verification was done properly but the popup doesnt get the number in time to show it. – Martin Pizarro Apr 26 '21 at 13:01
@MartinPizarro - post your updated code (not pictures of it either). – Adam Jenkins Apr 26 '21 at 15:07
I answered my question with the updated code. – Martin Pizarro Apr 26 '21 at 15:23

score 0 · Answer 2 · answered Apr 26 '21 at 15:23

Thats how the function in the class ended up:

Future<void> loginQuery(String user, String password) async {
Firestore.instance
    .collection('Usuarios')
    .where('usuario', isEqualTo: user)
    .getDocuments()
    .then((QuerySnapshot docs) {
  if (docs.documents.isNotEmpty) {
    var w = docs.documents[0].data;

    if (w['contraseña'] == password) {
      print('Datos verificados correctamente');
      loginAccepted();
    } else {
      print('El usuario no existe o la contraseña no corresponde');
      loginDeclined();
    }
  }
});}

Thats how the button ended up:

ElevatedButton(
        onPressed: () async {
          await userMaster.loginQuery(
              loginUserController.text, loginPasswordController.text);
          if (userMaster.loginVerification == 1) {
            showDialog(
                context: context,
                builder: (_) => AlertDialog(
                      title: Text('Inicio de sesion correcto.'),
                    ),
                barrierDismissible: true);
          } else {
            Navigator.pop(context);
            showDialog(
                context: context,
                builder: (_) => AlertDialog(
                      title: Text('Credenciales incorrectas.'),
                    ),
                barrierDismissible: true);
          }

          // Navigate back to first route when tapped.
        },
        child: Text('Ingresar'),
      ),

You **did not** do what I said and use `async/await` in `loginQuery`. You **need** to `var docs = await Firestore.instance().collection(...).where(...).getDocuments()` — Adam Jenkins, Apr 26 '21 at 15:30
I didnt realize about the docs = await part, now I changed it and its working, thank you so much. — Martin Pizarro, Apr 26 '21 at 15:47

My flutter code is not reading the code in the order that I expect it to do it

2 Answers2