Factory Generator

Factory is created to help define easy to use model factories with predefined field assignment behaviour.

Factory title image

Post object creation example

Required boilerplate


Mark target class with Factory annotation

class Item {
  final int left;
  final int right;

  const Item(this.left, this.right);

class ItemFactory extends _$ItemFactory with FakerProviderMixin {
  ItemFactory([FactoryContext? context, ContextKey key = defaultKey])
      : super(context, key);

void main() {
  Item item;

  // Create item with random [left] and [right] parameters
  // provided by [FakerProvider].
  item = ItemFactory()
      .create(); // creates Item(left: {random value}, right: {random value})

  // Provide explicit value of [left] parameter to constructor.
  item = ItemFactory().create(
    left: fromValue(10),
  ); // creates Item(left: 10, right: {random value})

  // Depend on [left] parameter when building [right] parameter.
  // For now order of variables is crucial.
  // First parameters in constructor initialized earlier
  // of any further parameters.
  // If we try to depend on [right] when instantiating [left] it will be null.
  item = ItemFactory().create(
    left: fromValue(10),
    right: (context, key) =>
        context.read<ItemReadonlyBuilder, Item>(key.up()).getLeft()! + 10,
  ); // creates Item(left: 10, right: 10 + 10)

  try {
    item = ItemFactory().create(
      left: (context, key) =>
          context.read<ItemReadonlyBuilder, Item>(key.up()).getRight()!,
      right: fromValue(10),
    ); // not creates item because left trying
    // to initialize before right initialized.
  } on Object {
    print('failed to create item');