mikro-orm-better-auth

Better Auth adapter for MikroORM, with a createSchema implementation that generates MikroORM entity files via ts-morph.

Install

pnpm add better-auth @mikro-orm/core @mikro-orm/knex prettier ts-morph
pnpm add -D @better-auth/test-utils @mikro-orm/sqlite typescript vitest

Usage

import { betterAuth } from "better-auth";
import { mikroOrmAdapter } from "mikro-orm-better-auth";
import { MikroORM } from "@mikro-orm/core";
import { SqliteDriver } from "@mikro-orm/sqlite";

const orm = await MikroORM.init<SqliteDriver>({
  driver: SqliteDriver,
  dbName: "app.sqlite",
  entities: [],
});

export const auth = betterAuth({
  database: mikroOrmAdapter(() => orm.em),
});

With RequestContext (per-request EntityManager isolation):

import { RequestContext } from "@mikro-orm/core";

export const auth = betterAuth({
  database: mikroOrmAdapter(() => RequestContext.getEntityManager()! as SqlEntityManager),
});

Generate Entity

Better Auth calls the adapter's createSchema hook, and this adapter uses generateEntity as the configuration key for controlling entity generation. By default it writes to src/auth/entities, or to the directory implied by the output path Better Auth passes in.

const adapter = mikroOrmAdapter(() => orm.em, {
  generateEntity: {
    outputDir: "src/auth/entities",
  },
});

Generated files:

• use @Entity, @PrimaryKey, and @Property
• include one managed *.entity.ts file per Better Auth model
• reflect Better Auth table and field name transforms
• are patched in place on regeneration instead of being fully overwritten
• are formatted with Prettier before they are written, using the resolved config for the target file path
• preserve user-owned imports, decorators, methods, extra properties, and comments
• only update generator-owned fragments such as managed fields, types, and MikroORM decorators
• do not add management comments or sidecar state files to generated entities
• do not automatically delete existing files or unmatched properties during regeneration

Managed file boundaries:

• the generator owns Better Auth-managed fields and MikroORM decorators such as @Entity, @PrimaryKey, and @Property
• everything else in the file is treated as user-owned code and is preserved during regeneration whenever the file can be patched safely

Unsupported or rejected cases:

• if an existing file does not contain the expected exported entity class, generation fails instead of guessing how to patch it
• direct edits to generator-owned field definitions or MikroORM decorator arguments may be replaced on the next generation

Scope

• SQL-oriented runtime adapter using MikroORM's SQL entity manager
• create, update, updateMany, delete, deleteMany, findOne, findMany, count
• transaction support through em.transactional(...)
• native joins intentionally deferred

Test

pnpm test