How to insert an entity with OneToMany relation in NestJS?

Question

There is the description how to do this in typeorm official docs https://typeorm.io/#/many-to-one-one-to-many-relations. But I can't do the same in NestJS with Repository and insert method.

I have written these entities (other columns were omitted)

    @Entity()
    export class News {
      @OneToMany(type => NewsImage, image => image.news)
      public images: NewsImage[];
    }
    
    @Entity()
    export class NewsImage {
      @ManyToOne(type => News, news => news.images)
      public news: News;
    }

I have tried something like this

    function first() {
      const news = new News();
      const image = new NewsImage();
      news.images = [ image ];
      return from(this.newsRepo.insert(news))
        .pipe(
          switchMap(() => this.imageRepo.insert(image)),
        );
    }
    
    function second() {
      const news = new News();
      const image = new NewsImage();
      image.news = news;
      return from(this.imageRepo.insert(image))
        .pipe(
          switchMap(() => this.newsRepo.insert(news)),
        )
    }

It inserts news and image, but image's newsId is null.

pckben · Accepted Answer · 2022-07-28 09:39:33Z

35

Check cascade property

@Entity()
export class News {
  @OneToMany(type => NewsImage, image => image.news, { cascade: ['insert', 'update'] })
  public images: NewsImage[];
}

Then if you do something like

    let news = {
        images: [{
            date: "",
            etc: ""
        }],
        title: ""
    }

If then you call this.repository.save(news) it will save the news and the images. And updates too. Check more docs about this on typeorm docs.

edited Jul 28, 2022 at 9:39

pckben

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answered Mar 5, 2019 at 20:08

andressh11

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2 Comments

Benjamin Vison Over a year ago

How would you handle removing entities that are not in the images[] array, say for an update where an user removes one image from the array, it still exists in the database but instead of deleting the item typeorm/nestjs tries to set the newsId to null on the image @andressh11

andressh11 Over a year ago

here is a github issue regarding this : github.com/typeorm/typeorm/issues/1460 .

Jacob · Accepted Answer · 2019-03-03 03:57:16Z

1

Declaring new News() creates a new entity but does not save it to the database. You first need to insert or .save() the news object and then add it to image.

async function first() {
  // you can .save() it however you want, the point is it must be saved to the db
  const news = await News.create({ title: 'Async rules the world' }).save()
  const image = new NewsImage()
  image.news = news // now news has an id from the database
  // ...
}

answered Mar 3, 2019 at 3:57

Jacob

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1 Comment

msdosx86 Over a year ago

Thanks, I tried this way, but .insert returns InsertResult object, not news entity. I retrieved id from insertResults and set id to news, created image entity with that news and it works!

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