undo-drizzle-migration-during-merge.ts

undo-drizzle-migration-during-merge.ts

// MIT licensed (© 2024)
// https://opensource.org/license/mit
//
// Source: https://gist.github.com/anthonyjoeseph/102c0e3ea8496fe111029a8b8a95cc3a

// motivation:
// `drizzle-kit generate` has a default behavior that causes headaches
// it will randomly generate names for migration files
// e.g. "0012_swift_rhino.sql"
// this means that migration conflicts across branches are easy to miss
// e.g. one branch might have a migration called "0012_swift_rhino.sql"
// while another branch might have "0012_cold_inertia.sql"
// while the snapshots & _journal.json will have conflicts, the sql files won't
// and it's not immediately obvious how to resolve any of this

// usage:
// you should use the `--name` flag with drizzle-kit generate
// like so: `drizzle-kit generate --name migration`
// this will generate migrations that always look like this: "0023_migration.sql"
// forcing merge conflicts across branches
//
// in case of a merge conflict,
// use this script to undo your own migration
//
// it will run `git checkout --theirs ${path.join(config.out)}`
// and         `git add ${path.join(config.out)}`
// and then delete all of the migrations and snapshots
// that don't match the incoming branch

import { execSync } from "child_process";
import fs from "fs";
import path from "path";

import config from "../../drizzle.config";

const gitRoot = execSync("git rev-parse --show-toplevel").toString().trim();
if (!fs.existsSync(path.join(gitRoot, ".git", "MERGE_HEAD"))) {
  console.log("no 'git merge' in process");
  process.exit(0);
}

if (!config.out || !fs.existsSync(config.out)) {
  console.error(`Directory ${config.out} does not exist`);
  console.error("Maybe your drizzle.config.ts can't be found.");
  process.exit(1);
}

const files = fs.readdirSync(config.out).sort();

const snapshotFiles = fs.readdirSync(path.join(config.out, "meta")).sort();
console.log("Resetting migration files to the state of the current branch.");
execSync(`git checkout --theirs ${path.join(config.out)}`);
execSync(`git add ${path.join(config.out)}`);

// read the journal to identify which migrations to keep
const journal = JSON.parse(
  fs.readFileSync(path.join(config.out, "meta", "_journal.json"), "utf8"),
) as {
  entries: { idx: number; tag: string }[];
};

const sortedIdxs = journal.entries.sort(({ idx }, { idx: idx2 }) => idx - idx2);
const highestIdx = sortedIdxs[sortedIdxs.length - 1]?.idx;

if (highestIdx === undefined) {
  console.error("malformed _journal.json");
  process.exit(1);
}

console.log(`highest idx in _journal.json: ${highestIdx}`);

const unusedMigrations = files.filter((filename) => {
  if (!filename.endsWith(".sql")) return false;
  const [idx] = filename.split("_");
  return !idx || parseInt(idx) > highestIdx;
});

const unusedSnapshots = snapshotFiles.filter((filename) => {
  if (filename === "_journal.json") return false;
  const [idx] = filename.split("_");
  return !idx || parseInt(idx) > highestIdx;
});

for (const unusedMigration of unusedMigrations) {
  console.log(`deleting unused migration ${unusedMigration}`);
  fs.unlinkSync(path.join(config.out, unusedMigration));
}

for (const unusedSnapshot of unusedSnapshots) {
  console.log(`deleting unused snapshot ${unusedSnapshot}`);
  fs.unlinkSync(path.join(config.out, "meta", unusedSnapshot));
}