Relation for articles and tags with TypeORM in NestJS

Question

I'm actually creating an article system with associated tags by creating a relation table with the article ID and the tag ID.

The problem is that the relation is done for the first tag and not for the others and I have no idea of how to do this.

First, I'm receiving the tags as an array in the articles create DTO

import { ApiProperty } from '@nestjs/swagger';
import { IsNotEmpty } from 'class-validator';

export class CreateArticleDto {
    @ApiProperty()
    @IsNotEmpty()
    title: string;

    @ApiProperty()
    @IsNotEmpty()
    content: string;

    @ApiProperty()
    author: string;

    @ApiProperty()
    tags: Array<number>;

    @ApiProperty({ type: 'string', format: 'binary' })
    image: string;
}

Then, I create the relation in the articles module

@ManyToMany(() => TagsEntity)
@JoinTable({
  name: 'article_tags',
  joinColumn: {
    name: 'articleId',
    referencedColumnName: 'id',
  },
  inverseJoinColumn: {
    name: 'tagId',
    referencedColumnName: 'id',
  },
})
tags: TagsEntity[];

Moreover, here is my service for articles when I create the article

async createArticle(articleDto: CreateArticleDto) {
    const readingTime = Utils.estimateReadingTime(articleDto.content);
    const slug: string = Utils.slugify(articleDto.title);
    const tags: TagsEntity[] = await this.tagsRepository.findByIds(articleDto.tags);
    const articleEntity: ArticlesEntity = await this.articlesRepository.create({
      ...articleDto,
      readingTime,
      tags,
      slug,
    });

    return this.articlesRepository.save(articleEntity);
  }

The result is that if I try to create an article with 3 tags (id 1, id 2, id 3), there is only the article ID 1 with the tag ID 1 and not the tag ID 2 and 3 instead of having the article ID 1 three times with each tag ID.

Answer 1

Till you can share the code of your service, I've tried with the same entities and DTo you've used and I added all the tags without any problem: here is my create function :

async  create(createArticleDto: CreateArticleDto) {
 const article = new Article();
 article.title = createArticleDto.title;
 ...
 const tags: Tag[] = await this.tagRepository.findByIds(createArticleDto.tags);
   article.tags = tags;
return await this.articleRepository.save(article);

}

UPDATE

After you comment, the problem is in the format fo the array you send to the Ws I think you're sending the array this way [tags]: 1,2,3

Instead, the way you should to send the array is:

tags[] : 1
tags[] : 2
tags[] : 4