Create nested Relationship

[dimas-cyriaco]

Is it possible to created a relationship object in the same request that creates other object?

For example:

If I have an Entity Student with a OneToMany relationship with Grade, can i pass something like this to the POST /students endpoint and have it create both the Student and the Grade?

{
  "data": {
    "type": "student",
    "attributes": {
      "name": "John Doe",
    },
    "relationships": {
      "grades": {
        "data": [{
          "attributes": {
            "score": "A"
          }
        }]
      }
    }
  }
}

[dimas-cyriaco]

Hi again.
I was reading the json:api docs and realized that the snippet I wrote before is not valid.

The content of the grades key should be a resource linked object. Since the docs says that the linkage can point to an 'included' object, I think maybe the snipped bellow could be the correct way of doing this.

Resource linkage in a compound document allows a client to link together all of the included resource objects

{
  "data": {
    "type": "student",
    "attributes": {
      "name": "John Doe",
    },
    "relationships": {
      "grades": {
        "data": [{
          "lid": "123",
        }]
      }
    },
    "included": [{
      "type": "grade",
      "lid": "123",
      "attributes": {
        "score": "A"
      }
    }]
  }
}

This snippet make use of a 'local id' to pass a new object to the endpoint.

Exception: The id member is not required when the resource object originates at the client and represents a new resource to be created on the server. In that case, a client MAY include a lid member to uniquely identify the resource by type locally within the document
font

Note: For resources that do not contain an id member but do contain a lid, the lid is sufficient to establish resource identity and thus linkage between resource objects and resource identifier objects throughout the document font

Do you think this is possiblle, or could be implemented? I would be happy to try to contribute this to the package.

[klerick]

@dimas-cyriaco
I tried to implement it, but got a lot problem with validate.
But if we use id as mandatory attribute i think it is possiblle.
you can try to implement it.

I already have utils method for link or unlink of relation:

nestjs-json-api/libs/json-api-nestjs/src/lib/mixin/service/typeorm/utils/utils-methode.ts

Line 309 in 2c96fe1

public static async *asyncIterateFindRelationships<T>(

so, I think need create other utils method which linked current relation with include.

but before, you need to change validation pipe(this pipe use json schema for validate)

[hygison]

@klerick Just to confirm then, we are able to post relationship as well now with values?

For example:

{
  "data": {
    "type": "question",
    "attributes": {
      "userId": "1",
      "title": "Winner"
    },
    "relationships": {
      "options": {
        "data": [
          {
            "id": "1",
            "type": "option",
            "attributes": {
              "name": "Team A",
              "description": "Team A"
            }
          },
          {
            "id": "2",
            "type": "option",
            "attributes": {
              "name": "Team B",
              "description": "Team B"
            }
          }
        ]
      }
    }
  }
}

Where:

@Entity()
export class Question extends CoreEntity {
  @Column({ type: 'bigint', unsigned: true, update: false, nullable: true })
  userId?: string;

  @Column({ type: 'varchar', length: 255 })
  title: string;

  @Column({ type: 'text' })
  description: string;

  @OneToMany(() => Option, (e) => e.question, { cascade: true, onDelete: 'CASCADE' })
  options: Option[];
}


@Entity()
export class Option extends CoreEntity {
  constructor(obj?: Partial<Option>) {
    super();
    if (obj) {
      Object.assign(this, obj);
    }
  }

  @Column({ type: 'bigint', unsigned: true, update: false })
  bolaoId: string;

  @ManyToOne(() => Question, (e) => e.options, { onDelete: 'CASCADE' })
  @JoinColumn({ name: 'bolao_id', referencedColumnName: 'id' })
  question: Question;

  @Column({ type: 'varchar', update: false })
  name: string;

  @Column({ type: 'text', update: false, default: '' })
  description: string;
}

[klerick]

No, you can only create link. if you want to create/update relation in one request you can try to use atomic operation