KeiSeiKit-1.0/_primitives/_rust/kei-migrate/src/cmd_down.rs
Parfii-bot df857923d4 feat(primitives): kei-migrate Rust universal migration runner
Single binary, three backends (Postgres/SQLite/MySQL) autodetected
from DATABASE_URL scheme. Sequential .sql migrations tracked in
_kei_migrations with SHA-256 checksums.

Commands:
  kei-migrate up              — apply pending
  kei-migrate down [n]        — revert last N (requires .down.sql)
  kei-migrate status          — list applied vs pending
  kei-migrate create <name>   — scaffold up+down pair with UTC ts

Constructor Pattern: 10 source files, all <90 LOC, functions <30 LOC.
Deps: sqlx 0.8 (any+postgres+sqlite+mysql, rustls), clap 4, chrono,
sha2, anyhow, tokio.

Tests: 9/9 passing (cargo test, SQLite backend).
Clippy clean: cargo clippy --all-targets -- -D warnings.

Safety features:
- checksum drift detection on applied migrations
- IRREVERSIBLE marker blocks down-revert
- duplicate version detection at scan time
- each migration in its own transaction

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-04-21 20:35:29 +08:00

58 lines
2 KiB
Rust

//! `kei-migrate down [n]` — revert the last N applied migrations.
//!
//! Requires a sibling `<version>_<name>.down.sql` for each target. Missing
//! down-file = hard error — we don't guess reversals.
use crate::discover::Migration;
use crate::tracker;
use anyhow::{bail, Context, Result};
use sqlx::AnyPool;
use std::collections::HashMap;
/// Revert the last `n` applied migrations in reverse order.
pub async fn run(pool: &AnyPool, migrations: &[Migration], n: u32) -> Result<u32> {
let mut applied: Vec<i64> = tracker::applied_versions(pool).await?;
applied.sort_unstable();
applied.reverse(); // newest first
let by_version: HashMap<i64, &Migration> =
migrations.iter().map(|m| (m.version, m)).collect();
let mut reverted = 0u32;
for v in applied.into_iter().take(n as usize) {
let m = by_version.get(&v).with_context(|| {
format!("applied version {} has no matching file on disk", v)
})?;
revert_one(pool, m).await?;
reverted += 1;
println!("[down] {} {} — reverted", m.version, m.name);
}
Ok(reverted)
}
async fn revert_one(pool: &AnyPool, m: &Migration) -> Result<()> {
let down_path = m.down_path.as_ref().ok_or_else(|| {
anyhow::anyhow!(
"no down-sql for migration {} ({}) — create {}_{}.down.sql",
m.version,
m.name,
m.version,
m.name
)
})?;
let sql = std::fs::read_to_string(down_path)
.with_context(|| format!("read {}", down_path.display()))?;
if sql.contains("-- IRREVERSIBLE") {
bail!(
"migration {} ({}) is marked IRREVERSIBLE — refusing to run down-sql",
m.version,
m.name
);
}
let mut tx = pool.begin().await?;
sqlx::raw_sql(&sql)
.execute(&mut *tx)
.await
.with_context(|| format!("revert migration {} ({})", m.version, m.name))?;
tx.commit().await?;
tracker::record_down(pool, m.version).await?;
Ok(())
}