Form class

A container widget that coordinates focus, validation, and resets for multiple FormField widgets.

Form can be used in two ways:

1. Legacy Mode: By providing a flat list of form fields directly via the fields parameter.
2. Declarative Mode: By passing a child widget tree containing nested form fields.

Under declarative mode, form fields can be nested inside columns, rows, padding, or custom widgets. They will dynamically locate and register their state with the Form using an inherited widget lookup.

Example (Declarative Mode)

Form(
  child: Column([
    TextFormField(
      label: 'Username',
      validator: (val) => (val == null || val.isEmpty) ? 'Required' : null,
    ),
    ConfirmFormField(
      label: 'Accept terms',
    ),
  ]),
)

Inheritance

• Object
• Widget
• StatefulWidget
• Form

Constructors

Form({Widget? child, List<FormField> fields = const []})

Creates a Form to group multiple input fields.

Properties

activeFieldIndex ↔ int

The index of the currently active form field.

getter/setter pair

child → Widget?

The child subtree containing form fields. Used in Declarative Mode.

final

fields → List<FormField>

A flat list of form fields. Used in Legacy Mode.

final

hashCode → int

The hash code for this object.

no setter, inherited

key → Key?

The optional key for this widget.

final, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

createElement() → Element

Creates an Element to manage this widget's location in the tree.

inherited

createState() → State<StatefulWidget>

Creates the mutable state for this widget at a given location in the tree.

override

getIntrinsicHeight(int width) → int

Computes the intrinsic height of this widget under the given width constraint.

inherited

handleKeyEvent(KeyEvent event) → void

Moves focus between fields using Tab/Shift-Tab, and routes other events to the active field.

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

render(Buffer buffer, Rect area) → void

Renders the widget onto the provided buffer within the specified area.

inherited

toString() → String

A string representation of this object.

inherited

validate() → bool

Validates all child fields, returning true if all are valid.

Operators

operator ==(Object other) → bool

The equality operator.

inherited

Static Methods

of(BuildContext context) → FormState?

Retrieves the closest ancestor FormState in the tree.