Example of Dynamic Widget Creation

dynamic_widget_creation.dart

import 'package:flutter/material.dart';

abstract class Event {}

class TTimeEntryCreated extends Event {}

class TTimeEntryEdited extends Event {}

class TTimeEntryDeleted extends Event {}

class TStripeChargeCreated extends Event {}

typedef EventWidgetBuilder = Widget Function(BuildContext context, Event event);

class Entry {
  Event sourceEvent;
  String memo;
}

class EntryWidget extends StatelessWidget {
  const EntryWidget({
    Key key,
    @required this.entry,
  }) : super(key: key);

  final Entry entry;

  @override
  Widget build(BuildContext context) {
    final event = entry.sourceEvent;
    if (event == null) {
      return Text(entry.memo);
    } else {
      final builder = _lookup[event.runtimeType];
      return builder?.call(context, event) ?? Text('Unknown');
    }
  }

  static const _lookup = <Type, EventWidgetBuilder>{
    TTimeEntryCreated: _buildTimeEntryCreated,
    TTimeEntryEdited: _buildTimeEntryEdited,
    TTimeEntryDeleted: _buildTimeEntryDeleted,
    TStripeChargeCreated: _buildStripeChargeCreated,
  };

  static Widget _buildTimeEntryCreated(BuildContext context, Event event) {
    return Text('TimeEntry Created');
  }

  static Widget _buildTimeEntryEdited(BuildContext context, Event event) {
    return Text('TimeEntry Edited');
  }

  static Widget _buildTimeEntryDeleted(BuildContext context, Event event) {
    return Text('TimeEntry Deleted');
  }

  static Widget _buildStripeChargeCreated(BuildContext context, Event event) {
    return Text('Stripe Charge Created');
  }
}