feat(mongo): add support for migrations in mongo driver

Adds new `@mikro-orm/migrations-mongodb` package that needs to be explicitly installed.
Current CLI commands will work with it transparently.

Mongo migrations have some limitations:
- no nested transaction support
- no schema diffing
- only blank migrations are generated
- use `this.driver` or `this.getCollection()` to manipulate with the database

Closes #295

docs/docs/migrations.md

@@ -2,10 +2,9 @@
 title: Migrations
 ---
 
-> To use migrations we need to first install `@mikro-orm/migrations` package.
+> To use migrations we need to first install `@mikro-orm/migrations` package for SQL driver or `@mikro-orm/migrations-mongodb` for MongoDB.
 
-MikroORM has integrated support for migrations via [umzug](https://github.com/sequelize/umzug).
-It allows us to generate migrations with current schema differences.
+MikroORM has integrated support for migrations via [umzug](https://github.com/sequelize/umzug). It allows us to generate migrations with current schema differences.
 
 > Since v5, migrations are stored without extension.
 
@@ -284,6 +283,36 @@ await MikroORM.init({
 });
 ```
 
+## MongoDB support
+
+Support for migrations in MongoDB has been added in v5.3. There are some limitations to it:
+
+- uses `@mikro-orm/migrations-mongodb` package
+- no nested transaction support
+- no schema diffing
+- only blank migrations are generated
+- use `this.driver` or `this.getCollection()` to manipulate with the database
+
+> Current CLI commands will work with it transparently.
+
+Example migration in mongo:
+
+```ts
+import { Migration } from '@mikro-orm/migrations-mongodb';
+
+export class MigrationTest1 extends Migration {
+
+  async up(): Promise<void> {
+    // use `this.getCollection()` to work with the mongodb collection directly 
+    await this.getCollection('Book').updateMany({}, { $set: { updatedAt: new Date() } });
+
+    // or use `this.driver` to work with the `MongoDriver` API instead
+    await this.driver.nativeDelete('Book', { foo: true }, { ctx: this.ctx });
+  }
+
+}
+```
+
 ## Limitations
 
 ### MySQL

packages/cli/package.json

@@ -79,6 +79,7 @@
     "@mikro-orm/entity-generator": "^5.0.0",
     "@mikro-orm/mariadb": "^5.0.0",
     "@mikro-orm/migrations": "^5.0.0",
+    "@mikro-orm/migrations-mongodb": "^5.0.0",
     "@mikro-orm/mongodb": "^5.0.0",
     "@mikro-orm/mysql": "^5.0.0",
     "@mikro-orm/postgresql": "^5.0.0",
@@ -92,6 +93,9 @@
     "@mikro-orm/migrations": {
       "optional": true
     },
+    "@mikro-orm/migrations-mongodb": {
+      "optional": true
+    },
     "@mikro-orm/seeder": {
       "optional": true
     },

packages/cli/src/commands/MigrationCommandFactory.ts

@@ -1,8 +1,6 @@
 import type { ArgumentsCamelCase, Argv, CommandModule } from 'yargs';
 import type { Configuration, MikroORM, MikroORMOptions, IMigrator } from '@mikro-orm/core';
 import { Utils, colors } from '@mikro-orm/core';
-import type { AbstractSqlDriver } from '@mikro-orm/knex';
-import { SchemaGenerator } from '@mikro-orm/knex';
 import type { MigrateOptions } from '@mikro-orm/migrations';
 import { CLIHelper } from '../CLIHelper';
 
@@ -85,9 +83,8 @@ export class MigrationCommandFactory {
 
   static async handleMigrationCommand(args: ArgumentsCamelCase<Options>, method: MigratorMethod): Promise<void> {
     const options = { pool: { min: 1, max: 1 } } as Partial<MikroORMOptions>;
-    const orm = await CLIHelper.getORM(undefined, options) as MikroORM<AbstractSqlDriver>;
-    const { Migrator } = await import('@mikro-orm/migrations');
-    const migrator = new Migrator(orm.em);
+    const orm = await CLIHelper.getORM(undefined, options);
+    const migrator = orm.getMigrator();
 
     switch (method) {
       case 'create':
@@ -167,8 +164,8 @@ export class MigrationCommandFactory {
     CLIHelper.dump(colors.green(`${ret.fileName} successfully created`));
   }
 
-  private static async handleFreshCommand(args: ArgumentsCamelCase<Options>, migrator: IMigrator, orm: MikroORM<AbstractSqlDriver>) {
-    const generator = new SchemaGenerator(orm.em);
+  private static async handleFreshCommand(args: ArgumentsCamelCase<Options>, migrator: IMigrator, orm: MikroORM) {
+    const generator = orm.getSchemaGenerator();
     await generator.dropSchema({ dropMigrationsTable: true });
     CLIHelper.dump(colors.green('Dropped schema successfully'));
     const opts = MigrationCommandFactory.getUpDownOptions(args);

packages/core/package.json

@@ -71,6 +71,7 @@
     "@mikro-orm/entity-generator": "^5.0.0",
     "@mikro-orm/mariadb": "^5.0.0",
     "@mikro-orm/migrations": "^5.0.0",
+    "@mikro-orm/migrations-mongodb": "^5.0.0",
     "@mikro-orm/mongodb": "^5.0.0",
     "@mikro-orm/mysql": "^5.0.0",
     "@mikro-orm/postgresql": "^5.0.0",
@@ -87,6 +88,9 @@
     "@mikro-orm/migrations": {
       "optional": true
     },
+    "@mikro-orm/migrations-mongodb": {
+      "optional": true
+    },
     "@mikro-orm/mongodb": {
       "optional": true
     },

packages/core/src/drivers/DatabaseDriver.ts

@@ -63,9 +63,9 @@ export abstract class DatabaseDriver<C extends Connection> implements IDatabaseD
     await this.nativeUpdate<T>(coll.owner.constructor.name, coll.owner.__helper!.getPrimaryKey() as FilterQuery<T>, data, options);
   }
 
-  mapResult<T>(result: EntityDictionary<T>, meta: EntityMetadata<T>, populate: PopulateOptions<T>[] = []): EntityData<T> | null {
+  mapResult<T>(result: EntityDictionary<T>, meta?: EntityMetadata<T>, populate: PopulateOptions<T>[] = []): EntityData<T> | null {
     if (!result || !meta) {
-      return null;
+      return result ?? null;
     }
 
     return this.comparator.mapResult(meta.className, result);

packages/core/src/typings.ts

@@ -497,11 +497,11 @@ export interface IMigratorStorage {
   logMigration(params: Dictionary): Promise<void>;
   unlogMigration(params: Dictionary): Promise<void>;
   getExecutedMigrations(): Promise<MigrationRow[]>;
-  ensureTable(): Promise<void>;
+  ensureTable?(): Promise<void>;
   setMasterMigration(trx: Transaction): void;
   unsetMasterMigration(): void;
   getMigrationName(name: string): string;
-  getTableName(): { schemaName: string; tableName: string };
+  getTableName?(): { schemaName?: string; tableName: string };
 }
 
 export interface IMigrator {

packages/migrations-mongodb/.npmignore

@@ -0,0 +1,8 @@
+node_modules
+src
+tests
+coverage
+temp
+yarn-error.log
+data
+tsconfig.*

packages/migrations-mongodb/package.json

@@ -0,0 +1,73 @@
+{
+  "name": "@mikro-orm/migrations-mongodb",
+  "version": "5.2.4",
+  "description": "TypeScript ORM for Node.js based on Data Mapper, Unit of Work and Identity Map patterns. Supports MongoDB, MySQL, PostgreSQL and SQLite databases as well as usage with vanilla JavaScript.",
+  "main": "dist/index.js",
+  "module": "dist/index.mjs",
+  "typings": "dist/index.d.ts",
+  "exports": {
+    "./package.json": "./package.json",
+    ".": {
+      "import": {
+        "types": "./dist/index.d.ts",
+        "default": "./dist/index.mjs"
+      },
+      "require": "./dist/index.js"
+    }
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+ssh://git@github.com/mikro-orm/mikro-orm.git"
+  },
+  "keywords": [
+    "orm",
+    "mongo",
+    "mongodb",
+    "mysql",
+    "mariadb",
+    "postgresql",
+    "sqlite",
+    "sqlite3",
+    "ts",
+    "typescript",
+    "js",
+    "javascript",
+    "entity",
+    "ddd",
+    "mikro-orm",
+    "unit-of-work",
+    "data-mapper",
+    "identity-map"
+  ],
+  "author": "Martin Adámek",
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/mikro-orm/mikro-orm/issues"
+  },
+  "homepage": "https://mikro-orm.io",
+  "engines": {
+    "node": ">= 14.0.0"
+  },
+  "scripts": {
+    "build": "yarn clean && yarn compile && yarn copy",
+    "postbuild": "yarn gen-esm-wrapper dist/index.js dist/index.mjs",
+    "clean": "rimraf ./dist",
+    "compile": "tsc -p tsconfig.build.json",
+    "copy": "ts-node -T ../../scripts/copy.ts"
+  },
+  "publishConfig": {
+    "access": "public"
+  },
+  "dependencies": {
+    "@mikro-orm/mongodb": "^5.2.4",
+    "fs-extra": "10.1.0",
+    "mongodb": "^4.8.1",
+    "umzug": "3.1.1"
+  },
+  "devDependencies": {
+    "@mikro-orm/core": "^5.2.4"
+  },
+  "peerDependencies": {
+    "@mikro-orm/core": "^5.0.0"
+  }
+}

packages/migrations-mongodb/src/JSMigrationGenerator.ts

@@ -0,0 +1,31 @@
+import { MigrationGenerator } from './MigrationGenerator';
+
+export class JSMigrationGenerator extends MigrationGenerator {
+
+  /**
+   * @inheritDoc
+   */
+  generateMigrationFile(className: string, diff: { up: string[]; down: string[] }): string {
+    let ret = `'use strict';\n`;
+    ret += `Object.defineProperty(exports, '__esModule', { value: true });\n`;
+    ret += `const { Migration } = require('@mikro-orm/migrations-mongodb');\n\n`;
+    ret += `class ${className} extends Migration {\n\n`;
+    ret += `  async up() {\n`;
+    /* istanbul ignore next */
+    diff.up.forEach(sql => ret += this.createStatement(sql, 4));
+    ret += `  }\n\n`;
+
+    /* istanbul ignore next */
+    if (diff.down.length > 0) {
+      ret += `  async down() {\n`;
+      diff.down.forEach(sql => ret += this.createStatement(sql, 4));
+      ret += `  }\n\n`;
+    }
+
+    ret += `}\n`;
+    ret += `exports.${className} = ${className};\n`;
+
+    return ret;
+  }
+
+}

packages/migrations-mongodb/src/Migration.ts

@@ -0,0 +1,34 @@
+import type { Configuration, Transaction, EntityName } from '@mikro-orm/core';
+import type { MongoDriver } from '@mikro-orm/mongodb';
+import type { Collection } from 'mongodb';
+
+export abstract class Migration {
+
+  protected ctx?: Transaction;
+
+  constructor(protected readonly driver: MongoDriver,
+              protected readonly config: Configuration) { }
+
+  abstract up(): Promise<void>;
+
+  async down(): Promise<void> {
+    throw new Error('This migration cannot be reverted');
+  }
+
+  isTransactional(): boolean {
+    return true;
+  }
+
+  reset(): void {
+    this.ctx = undefined;
+  }
+
+  setTransactionContext(ctx: Transaction): void {
+    this.ctx = ctx;
+  }
+
+  getCollection(entityName: EntityName<any>): Collection {
+    return this.driver.getConnection().getCollection(entityName);
+  }
+
+}

packages/migrations-mongodb/src/MigrationGenerator.ts

@@ -0,0 +1,47 @@
+import { ensureDir, writeFile } from 'fs-extra';
+import type { IMigrationGenerator, MigrationsOptions, NamingStrategy } from '@mikro-orm/core';
+import { Utils } from '@mikro-orm/core';
+import type { MongoDriver } from '@mikro-orm/mongodb';
+
+/* istanbul ignore next */
+export abstract class MigrationGenerator implements IMigrationGenerator {
+
+  constructor(protected readonly driver: MongoDriver,
+              protected readonly namingStrategy: NamingStrategy,
+              protected readonly options: MigrationsOptions) { }
+
+  /**
+   * @inheritDoc
+   */
+  async generate(diff: { up: string[]; down: string[] }, path?: string): Promise<[string, string]> {
+    /* istanbul ignore next */
+    const defaultPath = this.options.emit === 'ts' && this.options.pathTs ? this.options.pathTs : this.options.path!;
+    path = Utils.normalizePath(this.driver.config.get('baseDir'), path ?? defaultPath);
+    await ensureDir(path);
+    const timestamp = new Date().toISOString().replace(/[-T:]|\.\d{3}z$/ig, '');
+    const className = this.namingStrategy.classToMigrationName(timestamp);
+    const fileName = `${this.options.fileName!(timestamp)}.${this.options.emit}`;
+    const ret = this.generateMigrationFile(className, diff);
+    await writeFile(path + '/' + fileName, ret);
+
+    return [ret, fileName];
+  }
+
+  /**
+   * @inheritDoc
+   */
+  createStatement(query: string, padLeft: number): string {
+    if (query) {
+      const padding = ' '.repeat(padLeft);
+      return `${padding}console.log('${query}');\n`;
+    }
+
+    return '\n';
+  }
+
+  /**
+   * @inheritDoc
+   */
+  abstract generateMigrationFile(className: string, diff: { up: string[]; down: string[] }): string;
+
+}

packages/migrations-mongodb/src/MigrationRunner.ts

@@ -0,0 +1,37 @@
+import type { MigrationsOptions, Transaction } from '@mikro-orm/core';
+import type { MongoDriver } from '@mikro-orm/mongodb';
+import type { Migration } from './Migration';
+
+export class MigrationRunner {
+
+  private readonly connection = this.driver.getConnection();
+  private masterTransaction?: Transaction;
+
+  constructor(protected readonly driver: MongoDriver,
+              protected readonly options: MigrationsOptions) { }
+
+  async run(migration: Migration, method: 'up' | 'down'): Promise<void> {
+    migration.reset();
+
+    if (!this.options.transactional || !migration.isTransactional()) {
+      await migration[method]();
+    } else if (this.masterTransaction) {
+      migration.setTransactionContext(this.masterTransaction);
+      await migration[method]();
+    } else {
+      await this.connection.transactional(async tx => {
+        migration.setTransactionContext(tx);
+        await migration[method]();
+      }, { ctx: this.masterTransaction });
+    }
+  }
+
+  setMasterMigration(trx: Transaction) {
+    this.masterTransaction = trx;
+  }
+
+  unsetMasterMigration() {
+    delete this.masterTransaction;
+  }
+
+}