Ask Your Question
1

Why is the TextFormField validator not functioning properly and displaying the error message "The method 'validate' was called on null"?

asked 2023-05-26 16:47:58 +0000

plato gravatar image

edit retag flag offensive close merge delete

1 Answer

Sort by ยป oldest newest most voted
3

answered 2023-05-26 17:17:01 +0000

scrum gravatar image

There could be several reasons why the TextFormField validator is not functioning properly and displaying the error message "The method 'validate' was called on null". Some possible reasons include:

  1. The validator function was not properly defined or passed to the TextFormField widget. Make sure that the validator function is defined as a named parameter and passed to the TextFormField widget, like this:
TextFormField(
  validator: (value) {
    if (value.isEmpty) {
      return 'Please enter some text';
    }
    return null;
  },
),
  1. The validator function is returning null instead of an error message when the input value is invalid. The validator function should return a string error message when the input is invalid, and null when the input is valid. Make sure that your validator function returns an error message when necessary, like in the example above.

  2. The TextFormField widget is not wrapped in a Form widget. The validate method of the TextFormField widget is meant to be called within a Form widget to validate all the form fields at once. Make sure that your TextFormField widget is wrapped in a Form widget, like this:

Form(
  child: TextFormField(
    validator: (value) {
      ...
    },
  ),
),
  1. The form key is not properly defined or passed to the Form widget. The validate method of the Form widget requires a global key to be passed, like this:
final _formKey = GlobalKey<FormState>();

...

Form(
  key: _formKey,
  child: ...
),

Make sure that your Form widget has a key defined and that it matches the key used in the validate method.

edit flag offensive delete link more

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account. This space is reserved only for answers. If you would like to engage in a discussion, please instead post a comment under the question or an answer that you would like to discuss

Add Answer


Question Tools

Stats

Asked: 2023-05-26 16:47:58 +0000

Seen: 18 times

Last updated: May 26 '23