How to create relation in mongoose

[kansson]

Hello, I have read the docs for relations with mongoose but I'm lost. I have created the relation between two DTOs but how do I actually link them together in GraphQL? I can create two individual entries but not figure out how to link them together. What mutations should I use and in what order?

Consider these two entries, Story and Comment. One of each can be created with createOne(Story/Comment) but when I try to use addCommentsToStory it returns AddRelations not supported for virtual relation comments. What am I doing wrong?

Thanks!

[smolinari]

What does your code look like for the two entities?

Also, this should be in discussions, as it isn't clear it is an issue. Converting.

Scott

[kansson]

Sorry for posting this as an issue and not a discussion. These are my two entities and their DTOs.

story.entity.ts

import { Prop, Schema, SchemaFactory } from '@nestjs/mongoose';
import { Document } from 'mongoose';

@Schema({ collection: 'stories' })
export class StoryEntity extends Document {
  @Prop({ required: true })
  title!: string;

  @Prop({ required: true })
  text!: string;
}

export const StorySchema = SchemaFactory.createForClass(StoryEntity);
StorySchema.virtual('comments', {
  ref: 'CommentEntity',
  localField: '_id',
  foreignField: 'story',
});

story.dto.ts

import {
  CursorConnection,
  FilterableField,
  IDField,
  KeySet,
} from '@nestjs-query/query-graphql';
import { ID, ObjectType } from '@nestjs/graphql';
import { CommentDTO } from 'src/comments/comment.dto';

@ObjectType('Story')
@KeySet(['id'])
@CursorConnection('comments', () => CommentDTO, { disableRemove: true })
export class StoryDTO {
  @IDField(() => ID)
  id!: string;

  @FilterableField()
  title!: string;

  @FilterableField()
  text!: string;
}

comment.entity.ts

import { Prop, Schema, SchemaFactory } from '@nestjs/mongoose';
import { Document, SchemaTypes, Types } from 'mongoose';

@Schema({ collection: 'comments' })
export class CommentEntity extends Document {
  @Prop({ type: SchemaTypes.ObjectId, ref: 'StoryEntity', required: true })
  story!: Types.ObjectId;

  @Prop({ required: true })
  text!: string;
}

export const CommentSchema = SchemaFactory.createForClass(CommentEntity);

comment.dto.ts

import {
  FilterableField,
  IDField,
  KeySet,
  Relation,
} from '@nestjs-query/query-graphql';
import { ID, ObjectType } from '@nestjs/graphql';
import { StoryDTO } from 'src/stories/story.dto';

@ObjectType('Comment')
@KeySet(['id'])
@Relation('story', () => StoryDTO, { disableRemove: true })
export class CommentDTO {
  @IDField(() => ID)
  id!: string;

  @FilterableField()
  text!: string;
}

My question is how I can create and link these two together through the relation.

[smolinari]

Where are you using the story model to "populate" the comments referencing the story?

Scott

[kansson]

I'm not sure if I'm doing that because I'm using the default NestjsQueryGraphQLModule to generate the CRUD routes and the NestjsQueryMongooseModule to handle the database interaction. Basically I followed the get started example and the one to many example for mongoose in the docs but with my own entities and DTOs.

I'm new to mongoose so is there something that I'm missing here?

Appreciate the help!

[kansson]

An update on what I found. If you create the story and comment separately with createOne(Story/Comment) and then set the story on the comment with setStoryOnComment the expected result is returned when querying the story with its comments. This works but is not ideal since the story field would be null on the comment until the set mutation has been called. Is there any way to do this in one mutation instead on the current solution? In some GraphQL CMSs you can connect a relation when creating the entity. Maybe this can be implemented somehow by modifying the DTOs?

Thanks

[smolinari]

Yes, so, usually you'd have the story written and published and when someone is commenting on it, the storyId is known. When the comment is written and should be saved, the storyId is also saved at that same time. Right? In other words, there would have to be a story first, before there can be any commenting. You don't need to have both created at the same time or at least you shouldn't.

Scott

[kansson]

Found out that you can have a custom CreateDTOClass to include the story when creating the comment as peer the mongoose example. https://github.com/doug-martin/nestjs-query/tree/master/examples/mongoose