(core) move home server into core

Summary: This moves enough server material into core to run a home server.  The data engine is not yet incorporated (though in manual testing it works when ported).

Test Plan: existing tests pass

Reviewers: dsagal

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2552

app/server/lib/dbUtils.ts

@@ -0,0 +1,67 @@
+import {synchronizeProducts} from 'app/gen-server/entity/Product';
+import {Connection, createConnection} from 'typeorm';
+
+// Summary of migrations found in database and in code.
+interface MigrationSummary {
+  migrationsInDb: string[];
+  migrationsInCode: string[];
+  pendingMigrations: string[];
+}
+
+// Find the migrations in the database, the migrations in the codebase, and compare the two.
+export async function getMigrations(connection: Connection): Promise<MigrationSummary> {
+  let migrationsInDb: string[];
+  try {
+    migrationsInDb = (await connection.query('select name from migrations')).map((rec: any) => rec.name);
+  } catch (e) {
+    // If no migrations have run, there'll be no migrations table - which is fine,
+    // it just means 0 migrations run yet.  Sqlite+Postgres report this differently,
+    // so any query error that mentions the name of our table is treated as ok.
+    // Everything else is unexpected.
+    if (!(e.name === 'QueryFailedError' && e.message.includes('migrations'))) {
+      throw e;
+    }
+    migrationsInDb = [];
+  }
+  // get the migration names in codebase.
+  // They are a bit hidden, see typeorm/src/migration/MigrationExecutor::getMigrations
+  const migrationsInCode: string[] = connection.migrations.map(m => (m.constructor as any).name);
+  const pendingMigrations = migrationsInCode.filter(m => !migrationsInDb.includes(m));
+  return {
+    migrationsInDb,
+    migrationsInCode,
+    pendingMigrations,
+  };
+}
+
+/**
+ * Run any needed migrations, and make sure products are up to date.
+ */
+export async function updateDb(connection?: Connection) {
+  connection = connection || await createConnection();
+  await runMigrations(connection);
+  await synchronizeProducts(connection, true);
+}
+
+export async function runMigrations(connection: Connection) {
+  // on SQLite, migrations fail if we don't temporarily disable foreign key
+  // constraint checking.  This is because for sqlite typeorm copies each
+  // table and rebuilds it from scratch for each schema change.
+  // Also, we need to disable foreign key constraint checking outside of any
+  // transaction, or it has no effect.
+  const sqlite = connection.driver.options.type === 'sqlite';
+  if (sqlite) { await connection.query("PRAGMA foreign_keys = OFF;"); }
+  await connection.transaction(async tr => {
+    await tr.connection.runMigrations();
+  });
+  if (sqlite) { await connection.query("PRAGMA foreign_keys = ON;"); }
+}
+
+export async function undoLastMigration(connection: Connection) {
+  const sqlite = connection.driver.options.type === 'sqlite';
+  if (sqlite) { await connection.query("PRAGMA foreign_keys = OFF;"); }
+  await connection.transaction(async tr => {
+    await tr.connection.undoLastMigration();
+  });
+  if (sqlite) { await connection.query("PRAGMA foreign_keys = ON;"); }
+}