Create child entity without having full parent entity (Postgres)

[vladkrasn]

Let's say I have these two entities

@Entity()
export class User {
	constructor(id: string, name: string) {
		this.id = id;
		this.name = name;
	}

	@PrimaryKey({ type: "uuid" })
	id!: string;

	@Property()
	name!: string;

	@OneToMany(
		() => Post,
		(post) => post.userId,
	)
	posts = new Collection<Post>(this);
}

@Entity()
export class Post {
	constructor(id: string, name: string, userId: string) {
		this.id = id;
		this.name = name;
		this.userId = userId;
	}

	@PrimaryKey({ type: "uuid" })
	id!: string;

	@Property()
	name!: string;

	@ManyToOne(() => User, { mapToPk: true })
	userId!: string;
}

When I try to create a new Post (in nest) like this:

postRepository.create({ id, name, userId })

It complains that User.name wasn't provided. Seems like I need to reference the full entity of User to create a Post. And I saw this pattern in documentation multiple times as well.

Is there a way to model the relationship so I can only provide the id instead of the full User instance? It should still not work if the id points to a User that does not exist

[B4nan]

It complains that User.name wasn't provided

You mean some runtime validation? Can you share the full error with a stack trace? I checked the tests and found a very similar test that works just fine. Maybe provide a complete reproduction so its clear what you are doing.

I would generally discourage using mapToPk, as you will lose a lot of features the ORM provides. Note that you can create an entity instance from its PK without loading it with em.getReference() (and this works natively in em.create and em.assign, just pass a FK value in place of a relation and the EM will create em.getReference automatically for you), so if that was the reason why you tried to use it, it's not really a reason to begin with. With mapToPk` you will be responsible for persisting such referenced entity yourself, you won't be able to leverage the UoW which can compute the order of queries and create what needs to be created first before it gets referenced.

[vladkrasn]

getReference() works for my use case, thank you!