Example of entity typing

connection.example.ts

const invoiceRepository = queryRunner.manager.getRepository("invoice");

// or

const invoiceRepository = connection.getRepository<Invoice>("invoice");

invoice.entity.ts

import { Entity, PrimaryGeneratedColumn, ManyToOne, Column } from "typeorm";
import { Base } from "./base.entity.ts"
import { User } from "./user.entity.ts"

@Entity()
export class Invoice extends Base {
  @ManyToOne((_type) => User)
  importedBy!: User | undefined;
    
  @Column({ nullable: false })
  importedById!: User["id"];
}

invoice.module-and-repository.example.ts

// in module.ts
import { Module } from "@nestjs/common";
import { TypeOrmModule } from "@nestjs/typeorm";
import { InvoiceRepository } from "./invoice.repository.ts";

@Module({
  imports: [TypeOrmModule.forFeature(InvoiceRepository)]
})

export class InvoiceModule {}


// in service.ts
import { Injectable } from "@nestjs/common";
import { InvoiceRepository } from "./invoice.repository.ts";

@Injectable()
export class InvoiceService {
  constructor(private readonly invoiceRepository: InvoiceRepository) {}
}

invoice.module.ts

import { Module } from "@nestjs/common";
import { TypeOrmModule } from "@nestjs/typeorm";
import { Invoice } from "./invoice.entity.ts";

@Module({ 
  imports: [TypeOrmModule.forFeature(Invoice)]
})

export class InvoiceModule {}

invoice.service.ts

import { Injectable } from "@nestjs/common";
import { InjectRepository, Repository, TypeOrmModule } from "@nestjs/typeorm";
import { Invoice } from "./invoice.entity.ts";

@Injectable()
export class InvoiceService {
  constructor(@InjectRepository(Invoice) private readonly invoiceRepository: Repository<Invoice>) {}
}

typesafe.example.ts

import { Entity, PrimaryGeneratedColumn, ManyToOne, Column } from "typeorm";
import { Base } from "./base.entity.ts"
import { User } from "./user.entity.ts"

@Entity()
export class Invoice extends Base {
  @ManyToOne((_type) => User)
  importedBy!: User | undefined;
  
  @Column({ nullable: false })
  importedById!: User["id"];
}

interface UserWithImportedBy extends User {
  importedBy: NonNullable<User["importedBy"]>;
}

const isUserWithImportedBy = (user: User): user is UserWithImportedBy => {
  return user.importedBy != null;
}
		

//When querying in repository
public async findWithImportedBy(userId: User["id"]): Promise<UserWithImportedBy> {
  const user = await this.findOneOrFail({
    where: { id: userId },
    relations: ["importedBy"],
	});

  if (!isUserWithImportedBy(user)) {
     throw new TypeError(`Could not load relation importedBy for user ${userId}`);
	}

  return user;
}

user.entity.ts

import { BaseEntity, Entity, PrimaryGeneratedColumn } from "typeorm";

@Entity()
export class User extends BaseEntity {
  @PrimaryGeneratedColumn("uuid")
  id!: string & { __brand: "userId" };
}