This is causes the hydration to fail since it doesn't know about those properties.

You said the properties don't map to actual db columns, right? So what hydration, how is it triggered (e.g. em.find or em.create? both are using hydrator internally) and where are the data coming from?

persist: false means it's not a real db column, so there is nothing to hydrate from.

@B4nan I've updated the description with the createQueryBuilder and query that I'm using. Hopefully this helps you understand the problem. Maybe we're using MikroORM wrong, but for us this seems like the proper way of adding a statistic embeddable to our entities.

That's surely not what embeddables were meant for, they represent actual values stored in the database.

@B4nan What would you suggest doing? I'm trying to find a solution in the documentation but I can't find a good solution. Is there already something we could use to map the query result? Maybe doing it this way via the @Embeddable is a good solution?

Also here you're mentioning a solution by using virtual properties by doing persistant: false. This is what I'm trying to do as well. Only thing is, virtual properties in embeddables don't get serialized.

I am not completely opposed to the idea, especially since it's not breaking anything apparently.

It feels a bit weird to achieve this by adding persist: false to every single scalar inside the embedded properties, it would be much cleaner to have that only on the @Embedded one itself (but I guess that would technically only cascade this to all the properties in the embeddable).

@B4nan should the @Embedded(() => Statistic, { persist: false }) override any @Property({ persist: true }) in the embeddable, or would it be better to add a persist: true on the @Embeddable decorator. That way it's less confusion maybe.

I don't think it should override anything, by declaring it on the parent you make everything inside virtual. persist: true is the default.

@B4nan but what to do in this case? Should it persist views or not? Right now it doesn't override anything. So the views column gets persisted and saved in the database.

@Entity()
class User {

  @PrimaryKey()
  id!: number;

  @Embedded(() => Statistic, { prefix: false, nullable: true, persist: false })
  statistic?: Statistic;
}

@Embeddable()
class Statistic {

    @Property({ type: DoubleType })
    total: number;

    @Property({ type: DoubleType, persist: true })
    views!: number;

    constructor(total: number) {
      this.total = total;
    }

}

No, I don't think so. This couldn't work in object mode at all anyway.

I'm not using object mode right? And if it should not persist the view column it should override persist: true in this case right? Just making sure everything works correctly :)

It should work in both modes, and yes, I would override it, since persist: true is technically the default anyway.

Maybe I need to add a test case for object mode as well then?

Let's focus on the default inline mode now.

Do no more changes are required?