FieldBuilder<T> class

A widget that automatically rebuilds the interface based on changes to the state of a FieldController.

The FieldBuilder is similar to a ValueListenableBuilder, but is specific for managing Formy fields. It watches a FieldController and rebuilds the widget whenever the field state changes.

This widget is useful to build complex interfaces that depend on the state of a form field.

Properties

• controller: The FieldController this widget will watch.
• child: A static widget that will not be rebuilt when the field state changes.
• builder: A function that returns the widget to be rebuilt. It receives:
  • context: The BuildContext from the widget tree.
  • field: The FieldController being observed.
  • child: The static widget defined in the child property.
• buildWhen: An optional function that returns true if the widget should rebuild. It receives:
  • oldState: The previous FieldState.
  • currentState: The current FieldState.

Example

FieldBuilder<String>(
  controller: FieldController(key: 'key'),
  builder: (context, field, child) {
    return TextField(
      controller: TextEditingController(text: field.value),
      decoration: InputDecoration(
        labelText: 'Name',
        errorText: field.firstError,
      ),
      onChanged: field.update,
    );
  },
)

See also

• FieldController, which manages the state of a field.