applyEvent<K> method

CollectionSnapshot<T> applyEvent<K>(CollectionEvent<T, K> event, { required K keyOf(T item), })

Returns a snapshot with event applied using keyOf.

Insertion upserts a matching key; updating or removing an absent key is a no-op. Insert/reorder indices are clamped. Reset clears failures and marks data ready/current. Refresh only changes presentation state and does not execute a loader. Pagination metadata is retained; update it separately when a source change affects totals or cursors.

Implementation

CollectionSnapshot<T> applyEvent<K>(
  CollectionEvent<T, K> event, {
  required K Function(T item) keyOf,
}) {
  switch (event) {
    case CollectionRefreshRequested<T, K>():
      return beginRefresh();
    case CollectionReset<T, K>():
      return copyWith(
        items: event.items,
        contentState: event.contentState,
        loadPhase: CollectionLoadPhase.ready,
        freshness: CollectionFreshness.current,
        clearInitialFailure: true,
        clearRefreshFailure: true,
      );
    case CollectionInserted<T, K>():
      final next = [...items];
      final existing = next.indexWhere((item) => keyOf(item) == event.key);
      if (existing >= 0) {
        next[existing] = event.item;
      } else {
        final index = (event.index ?? next.length).clamp(0, next.length);
        next.insert(index, event.item);
      }
      return copyWith(
        items: next,
        contentState: CollectionContentState.content,
      );
    case CollectionUpdated<T, K>():
      final index = items.indexWhere((item) => keyOf(item) == event.key);
      if (index < 0) return this;
      final next = [...items]..[index] = event.item;
      return copyWith(items: next);
    case CollectionRemoved<T, K>():
      final next = items.where((item) => keyOf(item) != event.key).toList();
      return next.length == items.length
          ? this
          : copyWith(
              items: next,
              contentState: next.isEmpty
                  ? event.emptyState
                  : CollectionContentState.content,
            );
    case CollectionReordered<T, K>():
      final from = items.indexWhere((item) => keyOf(item) == event.key);
      if (from < 0) return this;
      final next = [...items];
      final item = next.removeAt(from);
      next.insert(event.toIndex.clamp(0, next.length), item);
      return copyWith(items: next);
  }
}