What is the use of controller in Flutter?

FocusNode basically focuses on the keyboard event. Let’s suppose you want to control the TextFormField widget as soon as the user taps on it, then you use FocusNode . So, FocusNode class is basically an object that can be used to obtain keyboard focus and to handle keyboard events .

TextEditingController class Null safety. A controller for an editable text field . Whenever the user modifies a text field with an associated TextEditingController, the text field updates value and the controller notifies its listeners.

In flutter, controllers are a means to give control to the parent widget over its child state . The main selling point of controllers is that they remove the need of a GlobalKey to access the widget State. This, in turn, makes it harder to do anti-pattern stuff and increase performances.

onSaved. An optional method to call with the final value when the form is saved via FormState .

TextField is a simple text field. (you don’t care about user input) TextFormField is a text field to be used in a form (you care about user input) . If you don’t need to validate TextField . If you need to validate user input, use TextFormField with validator .