fix(mikro): infinite loop when using OneToOne eager loading

[zgid123]

I am using Mikro version 6.0.0-dev.75, I am not sure if version 5 face this issue or not. But I think it faces the same issue.

My usage is I have two models with OneToOne association, when eager loading, mikro-orm will load the model as reference, and then automapper will call serializeEntity infinitely.

Example:

@Entity()
export class Post extends Base {
  @AutoMap(() => SeriesPost)
  @OneToOne({
    ref: true,
    mappedBy: 'post',
    orphanRemoval: true,
    entity: () => SeriesPost,
  })
  seriesPost: Ref<SeriesPost>;

@Entity()
export class SeriesPost extends Base {
  @OneToOne({
    ref: true,
    entity: () => Post,
    deleteRule: 'cascade',
    inversedBy: 'seriesPost',
  })
  post: Ref<Post>;
}

In controller, I use

    return this.postRepository.findOneOrFail(
      {
        id,
      },
      {
        populate: [
          'seriesPost',
        ],
      },
    );

It will cause infinite loop because post.seriesPost.post is a reference of post.

The main idea of the fix is memorized the POJO/raw entity of the mikro-orm, then when we have a cycle, we will get from memorized instead of calling the serializeEntity.

Currently, when I do

    return this.postRepository.findOneOrFail(
      {
        id,
      },
      {
        populate: [
          'seriesPost',
          'seriesPost.post',
        ],
      },
    );

I cannot get the data of seriesPost.post, my project does not need that, but I still not know why it does not get that property. Maybe my config is wrong. I will test it later and will have a fix for this case (if it is a bug)

[zgid123]

one small issue I found out, if I have an entity

@Entity()
export class Series extends Base {
  @OneToMany(() => SeriesPost, (seriesPost) => seriesPost.series)
  seriesPosts = new Collection<SeriesPost>(this);

  @AutoMap()
  @Property({ persist: false })
  get chapterNumbers() {
    if (!this.seriesPosts.isInitialized()) {
      return 0;
    }

    return this.seriesPosts.length;
  }
}

when automapper runs, it will ignore the chapterNumbers

    if (!Utils.isEntity(item)) return item;
    if (toPojo) return wrap(item).toPOJO();

If we always returns wrap(item).toPOJO() here, we can get the chapterNumbers, but I am not sure the the design why we need to return the entity instead of its pojo.

When I use beforeMap, the source.chapterNumbers is undefined. I am not sure how we deal with this one. So if can, can you gimme the idea why we need return the entity instead of pojo?

[zgid123]

for version 6, we can do

const keys = Object.keys((wrap(item) as IWrappedEntityInternal<AnyEntity>).__meta.properties);

instead of

Reflect.ownKeys(item)

When using beforeMap, there is value for source.chapterNumbers, but the result does not contain it. I still not know why. I will try mikro-orm version 5 to test if it is working or not

[toonvanstrijp]

Version 5 of MikroORM is also facing this issue. We're facing the exact same issue as @zgid123, did you happen to find any work around to use until this gets merged?

[zgid123]

@toonvanstrijp currently I copy my fix to my repo and then import from that file instead of using the @automapper/mikro. I already contacted the author, but he is really busy. It will take time for this one to be merged

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
No Duplication information

[zgid123]

@toonvanstrijp FYI: I created a temporary package while waiting for the author here. I tested with my project and worked

[nartc]

Thanks @zgid123 for the PR