Method runMigrations

packages/migrations/src/Migrator.ts:198–235

(
    method: 'up' | 'down',
    options?: string | string[] | MigrateOptions,
  )

  }

  protected override async runMigrations(
    method: 'up' | 'down',
    options?: string | string[] | MigrateOptions,
  ): Promise<MigrationInfo[]> {
    const result = await super.runMigrations(method, options);

    if (result.length > 0 && this.options.snapshot) {
      const ctx = Utils.isObject<MigrateOptions>(options) ? options.transaction : undefined;
      const schema = await DatabaseSchema.create(
        this.em.getConnection(),
        this.em.getPlatform(),
        this.config,
        undefined,
        undefined,
        undefined,
        undefined,
        undefined,
        ctx,
      );

      // keep the snapshot authored by `migration:create` when the migrated DB still matches it
      // semantically — rewriting it from introspection only churns cosmetic serialization noise
      // (expression casing/reformatting, native-enum mapped type, index method, ...) into the diff
      const existing = await this.getSchemaFromSnapshot();

      if (existing && !this.snapshotDiffers(existing, schema)) {
        return result;
      }

      try {
        await this.storeCurrentSchema(schema);
      } catch {
        // Silently ignore for read-only filesystems (production).
      }
    }

    return result;
  }

  /** Whether the introspected schema differs from the snapshot in any way the comparator turns into SQL. */
  private snapshotDiffers(snapshot: DatabaseSchema, schema: DatabaseSchema): boolean {