TypeORM OneToMany causes "ReferenceError: Cannot access '<Entity>' before initialization"

Question

I have two entities: User and Habit. A user can create multiple Habits, thus I use a OneToMany relation on the User (and ManyToOne on the Habit, respectively).

User Entity

import {Entity, PrimaryGeneratedColumn, Column, CreateDateColumn, UpdateDateColumn, BeforeInsert, BeforeUpdate, OneToMany} from "typeorm";
import * as bcrypt from "bcryptjs";
import { Habit } from "../habits/habits.entity";

@Entity()
export class User {
    @PrimaryGeneratedColumn("uuid")
    id: string;

    @Column()
    name: string;

    @Column()
    email: string;

    @Column()
    password: string;

    @OneToMany(type => Habit, habit => habit.author)
    habits: Habit[];

    @CreateDateColumn()
    dateCreated: Date;

    @UpdateDateColumn()
    dateUpdated: Date;

    @BeforeInsert()
    @BeforeUpdate()
    async hashPassword(): Promise<void> {
        this.password = await bcrypt.hash(this.password,10);
    }

    async comparePassword(password: string): Promise<boolean> {
        return bcrypt.compare(password, this.password);
    }

    constructor(props: any) {
        Object.assign(this, props);
    }
}

Habit Entity

import {Column, CreateDateColumn, Entity, PrimaryGeneratedColumn, UpdateDateColumn, ManyToOne} from "typeorm";
import { User } from "../users/users.entity";

@Entity()
export class Habit {
    @PrimaryGeneratedColumn("uuid")
    id: string;

    @Column()
    name: string;

    @Column({ nullable: true})
    description?: string;

    @ManyToOne(type => User, user => user.habits)
    author: User;

    @CreateDateColumn()
    dateCreated: Date;

    @UpdateDateColumn()
    dateUpdated: Date;

    constructor(props: Partial<Habit>) {
        Object.assign(this, props);
    }
}

Problem

When setting up the above relation I receive the following error

WARNING in Circular dependency detected:
apps\api\src\habits\habits.entity.ts -> apps\api\src\users\users.entity.ts -> apps\api\src\habits\habits.entity.ts

WARNING in Circular dependency detected:
apps\api\src\users\users.entity.ts -> apps\api\src\habits\habits.entity.ts -> apps\api\src\users\users.entity.ts


/* harmony export (binding) */ __webpack_require__.d(__webpack_exports__, "User", function() { return User; });
                                                                                               ^
ReferenceError: Cannot access 'User' before initialization
    at Module.User (...\dist\apps\api\main.js:1782:96)
    at Module../apps/api/src/habits/habits.entity.ts (...\dist\apps\api\webpack:\apps\api\src\habits\habits.entity.ts:42:13)
    at __webpack_require__ (...\dist\apps\api\webpack:\webpack\bootstrap:19:1)
    at Module../apps/api/src/users/users.entity.ts (...\dist\apps\api\main.js:1790:79)
    at __webpack_require__ (...\dist\apps\api\webpack:\webpack\bootstrap:19:1)
    at Module../apps/api/src/config/db-config.service.ts (...\dist\apps\api\main.js:1038:77)
    at __webpack_require__ (...\dist\apps\api\webpack:\webpack\bootstrap:19:1)
    at Module../apps/api/src/config/config.module.ts (...\dist\apps\api\main.js:978:76)
    at __webpack_require__ (...\dist\apps\api\webpack:\webpack\bootstrap:19:1)
    at Module../apps/api/src/app/app.module.ts (...\dist\apps\api\main.js:147:79)

Note

I use Nx and have created a NestJS app. The TypeOrm version is "^0.2.22" and the @nestjs/typeorm version is "^6.2.0"

My tsconfig is as follows:

{
  "compileOnSave": false,
  "compilerOptions": {
    "rootDir": ".",
    "sourceMap": true,
    "declaration": false,
    "moduleResolution": "node",
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "importHelpers": true,
    "target": "es2015",
    "module": "esnext",
    "typeRoots": ["node_modules/@types"],
    "lib": ["es2018", "dom"],
    "skipLibCheck": true,
    "skipDefaultLibCheck": true,
    "baseUrl": ".",
    "paths": {
      "@awhile/contracts": ["libs/contracts/src/index.ts"],
      "@awhile/ui": ["libs/ui/src/index.ts"]
    }
  },
  "exclude": ["node_modules", "tmp"]
}

I have tried to use a ManyToMany relation and it worked. Also, on a separate NestJS app (without Nx) I cannot reproduce this reference error. Changing the ECMAScript target version in the tsconfig.json also did not work.

Both entities are only used in their services and are not instantiated anywhere else.

I appreciate any help. Thank you in advance.

Answer 1

Use the Relation type wrapper to avoid circular dependency issues, as described here.

For example:

import {Entity, OneToMany, Relation} from "typeorm";
import {Habit} from "../habits/habits.entity";

@Entity()
export class User {
    ...

    @OneToMany(type => Habit, habit => habit.author)
    habits: Relation<Habit>[];

    ...
}

Answer 2

In tsconfig, setting the target to "esnext" and module to "commonjs" fixed the issue for me

{
  "extends": "../../tsconfig.json",
  "compilerOptions": {
    "types": ["node", "jest"],
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "module": "commonjs",
    "target": "esnext"
  },
  "include": ["**/*.ts"]
}