Topic
Definition
A soft-delete leak occurs when a query intended to exclude logically deleted rows omits the deletion filter, causing removed records to still appear in lists, counts, or pagination totals.
In simpler words
Deleted tickets are not really gone from the database. If a query forgets to filter them out, they reappear in lists and mess up page counts.
Combines pagination correctness with a realistic soft-delete pitfall.
Definition
Soft delete marks a row as removed, for example with a deletion timestamp, without a physical delete, so every subsequent read query must explicitly exclude it, unlike a hard delete which removes the row from all future query results automatically.
In simpler words
Marking a row deleted does not stop it from showing up unless every query remembers to check for that mark.
A new query, index, or export path added later can easily forget the exclusion condition older queries already had. The leak often appears in only one endpoint, not all of them.
When the count query and the data query use different filters, the pagination total disagrees with what a user actually sees, producing an empty last page or missing rows.
Challenge lab
Deleted tickets still show up on later pages of the tickets list, and the last page is sometimes empty.
The paginated data query filters out soft-deleted tickets, but the separate count query used for the pagination total does not, so the total overcounts and the page math misaligns.
async list(page: number, limit: number) {
const [data] = await this.ticketsRepo.findAndCount({
where: { deletedAt: null },
skip: (page - 1) * limit,
take: limit,
});
const total = await this.ticketsRepo.count(); // forgot the deletedAt filter
return { data, meta: { page, limit, total } };
}Test
At least 10 questions — mix of concept, syntax, practical, and logic. Score ≥ 80% (enforced by the API) to save progress.
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10 questions · concept 3 · syntax 2 · practical 3 · logic 2