Method has automatic access to build context-CodePudding

Here is a method that is called within my application when a 'save' button is pressed. The method accesses a ChangeNotifier instance using the Provider object and updates the underlying model.

  /// Handle the user pressing the Submit button within the dialog.
  void _saveChanges() {
    // HANDLING DEGREE OBJECT //

    // degree title
    Provider.of<AcademicController>(context, listen: false)
        .setDegreeTitle(titleController.text);

    // degree award
    Provider.of<AcademicController>(context, listen: false)
        .setDegreeAward(awardController.text);

    // HANDLING ACADEMIC YEAR OBJECTS //

    // removing academic years to be removed
    Provider.of<AcademicController>(context, listen: false)
        .removeListOfAcademicYears(academicYearsToBeRemoved);

    // saving the changes made within to the academic year form rows
    for (AcademicYearFormRow academicYearFormRow in academicYearFormRows) {
      academicYearFormRow.saveChanges(context);
    }
  }

I am confused because, in this method, I reference context, but I do not pass in a BuildContext as an argument to the function.

The method is not nested and occurs at the same level as the widget's build method.

How does this method have access to a BuildContext without getting one as an argument?

CodePudding user response：

If your _saveChanges method is a member of a StatefulWidget's State, the context is most likely the State.context. The context passed to the State.build method is always the State.context and does not change over the lifetime of a State. According to the documentation of State.build

The BuildContext argument is provided redundantly here so that this method matches the signature for a WidgetBuilder.

CodePudding user response：

It depends whether that method is inside a StatelessWidget or a StatefulWidget. I find that for a StatefulWidget, the context is available globally within the class without needing to pass an instance of BuildContext to any method.