Delete Hooks

beforeDelete, afterDeleteSuccess, and afterDeleteError extension hooks.

Hook Signatures#

Future<void> beforeDelete(T object, Jwt? jwt);
Future<void> afterDeleteSuccess(T object, Jwt? jwt);
Future<void> afterDeleteError(Object error, Jwt? jwt);

object in all delete hooks is the row being (or that was) deleted. The hooks run once per row: a delete that matches ten rows calls beforeDelete ten times, then afterDeleteSuccess ten times.

beforeDelete#

Runs after rules pass, before the DELETE executes. Can abort by throwing. Nothing is deleted, and the client receives a 500 server error rather than your message:

@override
Future<void> beforeDelete(User user, Jwt? jwt) async {
  final orders = await get.many(
    tableName: 'orders',
    where: Eq('user_id', user.id.value),
    limit: 1,
  ) ?? [];
  if (orders.isNotEmpty) {
    throw Exception('Cannot delete user with open orders');
  }
}

Use for: checking for dependencies before deleting.

A throwing hook also discards anything it queued with mutate, so "throw, then mark the row deleted" does not work here. For soft deletes, have clients update a deletedAt column and deny delete in rules.

afterDeleteSuccess#

Runs after the DELETE commits. The row is gone — this hook cannot undo the deletion.

@override
Future<void> afterDeleteSuccess(Post post, Jwt? jwt) async {
  // Cascade: delete all comments on this post
  mutate.delete.many(
    tableName: 'comments',
    where: Eq('post_id', post.id.value),
  );
}

Each cascaded deletion goes through the full pipeline — row rules and extensions on comments also fire.

Use for: cascading deletes, releasing associated resources (photos, uploads), notifying external systems.

afterDeleteError#

Runs if the DELETE fails. Cannot make the operation succeed.

@override
Future<void> afterDeleteError(Object error, Jwt? jwt) async {
  logger.error('Delete failed: $error');
}

Example: Cascade Delete#

import 'package:my_app/src/schemas/posts.dart';
import 'package:zonai_schema/zonai_schema.dart';

class PostExtensions extends Extension<Post> {
  PostExtensions() : super(posts);

  @override
  Future<void> afterDeleteSuccess(Post post, Jwt? jwt) async {
    // Delete comments first, which triggers CommentExtensions hooks
    mutate.delete.many(
      tableName: 'comments',
      where: Eq('post_id', post.id.value),
    );

    // Also delete the post's cover photo if one exists
    final photoId = post.photo;
    if (photoId != null) {
      mutate.delete.one(
        tableName: '_photos',
        where: Eq('id', photoId),
      );
    }
  }
}

PostExtensions main() => PostExtensions();