Unhandled Exception: Failed assertion: boolean expression must not be null

Question

I'm making an edit profile page in my flutter app using laravel as my database. I got an error saying that my boolean expression must not be null. How would I be able to solve this?

void _update()async {

setState(() {
  _isLoading = true;
});
var userData;

var update = await Network().editData(userData, '/user Data');
var body = json.decode(update.body);
if(body['Done']){
  SharedPreferences localStorage = await SharedPreferences.getInstance();
  localStorage.setString('user Data', json.encode(body['user Data']));



  Navigator.push(
    context,
    new MaterialPageRoute(
        builder: (context) => Profile()
    ),
  );
}

setState(() {
  _isLoading = false;
});

} }

Here is the stacktrace:

E/flutter (28905): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)]
Unhandled Exception: Failed assertion: boolean expression must not be null
E/flutter (28905): #0 _EditState._update (package:project1app/screen/editprofile.dart:264:12)

Your userData variable is null. Set a value to it before this line of code: var update = await Network().editData(userData, '/user Data'); . Don't just copy pasting code and learn programming first. It will help you fix simple problems easily. — CoderUni
– CoderUni, Commented Mar 25, 2020 at 9:07
Does this answer your question? How do I solve the 'Failed assertion: boolean expression must not be null' exception in Flutter — Abhinav Sumaan
– Abhinav Sumaan, Commented Mar 25, 2020 at 10:59

Lucky · Accepted Answer · 2020-03-25 10:03:26Z

1

This problem occurs when one of your defined boolean type variable is not initialized with default value, for example maybe you have you bool _isLoading; is not defined as should bool _isLoading = false; or bool _isLoading = true;

answered Mar 25, 2020 at 10:03

Lucky

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2 Comments

user13423237 Over a year ago

Hi i know its already right but can you like tell us what to do so we can solve it. he almost has the same code as mine so please help me.

Lucky Over a year ago

@xAtifx you need to initialize _isLoading value either set it to true or false

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