This entry is answer for @MikroOrm's Tweet.

Hard to say what you are talking about just with the google translate, but sounds like you are struggling with decorators and next.js - the issue here is using babel (via next) instead of tsc - it compiles decorators based on different spec. Check this: https://t.co/PBGv1D5LlF
— MikroORM (@MikroOrm) 2021年1月26日

Abstract

As a result Everything works fine.
But I do not know the cause, but works fine(Can not reproduce ... sorry).
MikroORM works very well!
Thanks for your advice!

Logs

Phase 1. Next.js with MikroORM works fine.

I researched MikroORM and Next.js. And found following repository which I refer to.

github.com

It works fine.

(I couldn't reach following entry, but same author's lecture. Nice entry!) medium.com

Phase 2. Configuration.PLATFORMS require all driver ( Can not reproduce)

I wrote any code and refactoring( I think that detail of this is important, but I could'nt find it ). I saw an error as require @mikro-orm/mariadb but not found. I used Postgresql, and already installed @mikro-orm/postgresql worked fine on Phase 1. I tried installing @mikro-orm/mariadb, but another driver required.

Error line is Configuration.PLATFORMS

Configuration.PLATFORMS = {
    mongo: { className: 'MongoDriver', module: () => require('@mikro-orm/mongodb') },
    mysql: { className: 'MySqlDriver', module: () => require('@mikro-orm/mysql') },
    mariadb: { className: 'MariaDbDriver', module: () => require('@mikro-orm/mariadb') },
    postgresql: { className: 'PostgreSqlDriver', module: () => require('@mikro-orm/postgresql') },
    sqlite: { className: 'SqliteDriver', module: () => require('@mikro-orm/sqlite') },
};

I could not solve this.

Phase 3. I realized "Error occured by entity's Decorator on build for client"

I tried creating interface for client（not importing MikroORM's Decorators）, Errors not occured!

I thought that errors are solved by changing build config for client/server（ Following Tweet ）

next.jsがclient用とserver用で2回buildするのはそうだろうなと思うんだけど、その2回でtsconfigを切り替えたい時にどうしたら良いのか。https://t.co/xBZZ7W2qKT

少なくともファイル名はハードコーディング。dirを変えるか読んだ後の設定を編集できるか何かなんだろうか。しちゃだめなの？
— 佐藤正志@プログラミング個別トレーニングのサークルアラウンド (@ms2sato) 2021年1月25日

Phase 4. Omit Decorators and Use EntitySchema helper

Well, MicroORM provide EntitySchema helper as another method of creating schema. https://mikro-orm.io/docs/defining-entities#entityschema-helper

I tried and It works fine. Finally, EntitySchema helper's entity is few dependency and more simple code!

コンパイル通せた。やってみたらDBのschemaに関係するものが設定ファイル的になったのと、Entityとミスマッチしていればコンパイルエラーなので寧ろ良い感じに思える。

動くかどうかは見ていない。
— 佐藤正志@プログラミング個別トレーニングのサークルアラウンド (@ms2sato) 2021年1月25日

Phase 5. @MicroOrm's advice

Thanks for your kindness. I tried My problem reproducing from my past commit. But no errors occured. It works very well(I'm confused it). Unfortunately, I could not provide good report for this problem.

So MikroORM's developer's experience is very good. Thanks for your great work!

My package.json（save my versions）

{
  "name": "myapp",
  "version": "0.1.0",
  "private": true,
  "scripts": {
    "dev": "next dev",
    "build": "next build",
    "start": "next start",
    "test": "env TS_NODE_PROJECT=\"tsconfig.test.json\" mocha './test/**/*.spec.ts'",
    "test-single": "env TS_NODE_PROJECT=\"tsconfig.test.json\" mocha $@"
  },
  "dependencies": {
    "@babel/core": "^7.12.10",
    "@babel/plugin-proposal-class-properties": "^7.12.1",
    "@babel/plugin-proposal-decorators": "^7.12.12",
    "@material-ui/core": "^4.11.2",
    "@material-ui/icons": "^4.11.2",
    "@material-ui/lab": "^4.0.0-alpha.57",
    "@material-ui/pickers": "3.x.x",
    "@mikro-orm/core": "^4.3.4",
    "@mikro-orm/postgresql": "^4.3.4",
    "@mikro-orm/reflection": "^4.3.4",
    "babel-plugin-transform-typescript-metadata": "^0.3.1",
    "final-form": "^4.20.1",
    "firebase": "^8.1.1",
    "firebase-admin": "^9.4.2",
    "mui-rff": "^3.0.3",
    "next": "10.0.3",
    "react": "17.0.1",
    "react-dom": "17.0.1",
    "react-final-form": "^6.5.2",
    "react-query": "^3.5.11",
    "recoil": "^0.1.2",
    "utility-types": "^3.10.0",
    "yup": "^0.32.8"
  },
  "devDependencies": {
    "@firebase/rules-unit-testing": "^1.1.6",
    "@mikro-orm/cli": "^4.3.4",
    "@types/chai": "^4.2.14",
    "@types/mocha": "^8.2.0",
    "@types/node": "^14.14.10",
    "@types/react": "^17.0.0",
    "chai": "^4.2.0",
    "mocha": "^8.2.1",
    "ts-node": "^9.1.1",
    "typescript": "^4.1.2"
  },
  "mikro-orm": {
    "useTsNode": true,
    "tsConfigPath": "./tsconfig.orm.json",
    "configPaths": [
      "./db/mikro-orm.config.ts"
    ]
  }
}