max / makenotwork

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1	//! Database-error helpers: unique-violation (23505) detection/mapping and the
2	//! auto-suffixing unique-slug insert loop.
3
4	/// Maximum auto-suffix attempts when allocating a unique slug before giving up.
5	pub const SLUG_SUFFIX_CAP: u32 = 100;
6
7	/// Whether `e` is a Postgres unique-violation (SQLSTATE 23505), the slug
8	/// collision backstop every [`insert_with_unique_slug`] caller relies on.
9	pub fn is_unique_violation(e: &crate::error::AppError) -> bool {
10	matches!(
11	e,
12	crate::error::AppError::Database(sqlx::Error::Database(db_err))
13	if db_err.code().as_deref() == Some("23505")
14	)
15	}
16
17	/// Map a Postgres unique-violation (23505) into a clean `AppError::Conflict(msg)`;
18	/// pass any other error through unchanged. A create/insert on a deterministic or
19	/// user-supplied unique key that legitimately re-runs (a retry, a duplicate the
20	/// user can fix) should surface a 409 with a helpful message, not a raw 500
21	/// (ultra-fuzz Run 12 Storage: unhandled 23505 on lower-traffic create paths).
22	/// Use only where the INSERT has a single relevant unique constraint.
23	pub fn map_unique_violation(e: crate::error::AppError, msg: &str) -> crate::error::AppError {
24	if is_unique_violation(&e) {
25	crate::error::AppError::Conflict(msg.to_string())
26	} else {
27	e
28	}
29	}
30
31	/// Insert a row whose slug must be unique under a per-parent `UNIQUE` index,
32	/// auto-suffixing the slug (`base`, `base-2`, `base-3`, ...) on collision.
33	///
34	/// The `UNIQUE` index is the race-safe source of truth: `insert` is retried on a
35	/// 23505 unique violation, up to [`SLUG_SUFFIX_CAP`] attempts, so a concurrent
36	/// insert racing between any pre-check and this one can never surface a raw 500.
37	/// `insert` receives the candidate slug and performs the actual row insert.
38	/// Collapses the formerly copy-pasted suffix loops across blog posts, items, and
39	/// item/project sections (ultra-fuzz Run #1 UX, D1), including the internal
40	/// content route that previously pre-checked but did not retry the insert.
41	pub async fn insert_with_unique_slug<T, F, Fut>(
42	base: &str,
43	mut insert: F,
44	) -> crate::error::Result<T>
45	where
46	F: FnMut(String) -> Fut,
47	Fut: std::future::Future<Output = crate::error::Result<T>>,
48	{
49	let mut slug = base.to_string();
50	let mut suffix = 1u32;
51	loop {
52	match insert(slug.clone()).await {
53	Ok(value) => return Ok(value),
54	Err(e) if is_unique_violation(&e) && suffix < SLUG_SUFFIX_CAP => {
55	suffix += 1;
56	slug = format!("{base}-{suffix}");
57	}
58	Err(e) => return Err(e),
59	}
60	}
61	}
62