Correctly Saving and Updating Entites in Netsjs+TypeORM - nestjs

Question

I've got a Question regarding TypeORM-Relations and how to use them 'nest-like'.
Suppose I have two Entities defined ChildEntity and TestEntity, which are related.
TestEntity:
import { ChildEntity } from 'src/modules/child-entity/entities/child-entity.entity';
import { Column, Entity, ManyToOne, PrimaryGeneratedColumn } from 'typeorm';
#Entity()
export class TestEntity {
#PrimaryGeneratedColumn()
id: number;
#Column('varchar')
name: string;
#ManyToOne(() => ChildEntity, (childEntity) => childEntity.testEntities)
childEntity: ChildEntity;
constructor(name: string, childEntity: ChildEntity) {
this.name = name;
this.childEntity = childEntity;
}
}
My first question occurs when I want to create the entity. I have to first translate the passed childEntityId into a ChildEntity, which I can pass to the constructor:
CreateTestEntityDto
import { ApiProperty } from '#nestjs/swagger';
import { IsNotEmpty, IsNumber } from 'class-validator';
export class CreateTestEntityDto {
#ApiProperty()
#IsNotEmpty()
name: string;
#ApiProperty()
#IsNumber()
childEntityId: number;
constructor(name: string, childEntityId: number) {
this.name = name;
this.childEntityId = childEntityId;
}
}
async create(createTestEntityDto: CreateTestEntityDto) {
const { name, childEntityId } = createTestEntityDto;
const childEntity = await this.childEntityService.findOne(childEntityId);
const testEntity = new TestEntity(name, childEntity);
return this.testEntityRepo.save(testEntity);
}
Is there a way to just pass the childEntityId to the save()-Method without explicitly looking for the ChildEntity beforehand?
The Second problem occurs when updating.
UpdateTestEntityDto
import { PartialType } from '#nestjs/swagger';
import { CreateTestEntityDto } from './create-test-entity.dto';
export class UpdateTestEntityDto extends PartialType(CreateTestEntityDto) {}
As updating only a partial Entity is possible I have to check if the Id is even passed along the request and if it is I have to retrieve the correct Entity for the update. Is there a more streamlined way to do this?
async update(id: number, updateTestEntityDto: UpdateTestEntityDto) {
const { name, childEntityId } = updateTestEntityDto;
const props = { name };
if (childEntityId) {
props['childEntity'] = await this.childEntityService.findOne(
childEntityId,
);
}
return this.testEntityRepo.update(id, props);
}

Answer 1

You should add a childEntityId to the test entity:
#Entity()
export class TestEntity {
#PrimaryGeneratedColumn()
id: number;
#Column('varchar')
name: string;
#Column('int')
childEntityId: number;
#ManyToOne(() => ChildEntity, (childEntity) => childEntity.testEntities)
childEntity: ChildEntity;
...
}
and then you can use it to set the id directly. Something like:
async create(dto: Dto) {
const { name, childEntityId } = dto;
const entity = new TestEntity();
entity.name = name;
entity.childEntityId = childEntityId;
return this.testEntityRepo.save(entity);
}
Check this out.

Answer 2

1.) Saving relational entity
There's no need to do all these roundtrips cluttering to save the entity. While, the solution given by #UrosAndelic works but still there's no need to write 3 extra lines of code.
If you hover over a relational param inside the create() method of the repository from an IDE, you'll notice that it accepts two types. First, An Instance of an entity OR Second, a DeepPartial object of an entity.
For instance:
const entity = this.testEntityRepo.create({
name: 'Example 1',
childEntity: {
id: childEntityId // notice: it's a DeepPartial object of ChildEntity
}
})
await this.testEntityRepo.save(entity)
2.) Updating entity
There's no need for child entity's id if you are updating test entity. You can simply update the props of test entity.
const testEntityId = 1;
await this.testEntityRepo.update(testEntityId, {
name: 'Example 2'
})
This will update the name of TestEntity = 1;