Relations

Relations work a little differently in typegoose when compared to other relational ORMs such as sequelize or typeorm. You can read more about relations (references) in typegoose [here](https://mongoosejs.com/docs/populate .html)

note

There are multiple ways to set of references in Typegoose. These are intended as a starting point.

warning

Filtering on references is not supported by Typegoose.

One to Many/Many To One Example

To set up a one to many/many to one relationship in Typegoose, you will store a reference in your document.

For example, lets add sub tasks to our todo items by storing a todoItem ref on our subTask and an array of sub-tasks on our todoItem entity.

TodoItemEntity

todo-item/todo-item.entity.ts

import { Prop, modelOptions } from '@typegoose/typegoose';import { Base } from '@typegoose/typegoose/lib/defaultClasses';
@modelOptions({ schemaOptions: { timestamps: true } })export class TodoItemEntity extends Base {  @Prop({ required: true })  title!: string;
  @Prop()  description?: string;
  @Prop({ required: true })  completed!: boolean;
  @Prop({ default: Date.now })  createdAt!: Date;
  @Prop({ default: Date.now })  updatedAt!: Date;
  @Prop({ default: 0 })  priority!: number;
  @Prop({ ref: () => SubTaskEntity })  subTasks: Ref<SubTaskEntity>[];
  @Prop()  createdBy?: string;
  @Prop()  updatedBy?: string;}

SubTaskEntity

sub-task/sub-task.entity.ts

import { Prop, modelOptions, Ref } from '@typegoose/typegoose';import { Base } from '@typegoose/typegoose/lib/defaultClasses';
@modelOptions({ schemaOptions: { timestamps: true } })export class SubTaskEntity extends Base {  @Prop({ required: true })  title!: string;
  @Prop()  description?: string;
  @Prop({ required: true })  completed!: boolean;
  @Prop({ ref: () => TodoItemEntity, required: true })  todoItem!: Ref<TodoItemEntity>;
  @Prop()  createdAt!: Date;
  @Prop()  updatedAt!: Date;
  @Prop()  createdBy?: string;
  @Prop()  updatedBy?: string;}

Now that we have the relationships defined, we can add the @Relation and @Connection to our DTOs

TodoItemDTO

todo-item/todo-item.dto.ts

import { FilterableField, IDField, KeySet, Connection } from '@nestjs-query/query-graphql';import { ObjectType, ID, GraphQLISODateTime, Field } from '@nestjs/graphql';import { SubTaskDTO } from '../../sub-task/dto/sub-task.dto';
@ObjectType('TodoItem')@KeySet(['id'])// disable the remove because mongoose does not support removing a virtual@Connection('subTasks', () => SubTaskDTO, { disableRemove: true })export class TodoItemDTO {  @IDField(() => ID)  id!: string;
  @FilterableField()  title!: string;
  @FilterableField({ nullable: true })  description?: string;
  @FilterableField()  completed!: boolean;
  @FilterableField(() => GraphQLISODateTime)  createdAt!: Date;
  @FilterableField(() => GraphQLISODateTime)  updatedAt!: Date;
  @Field()  age!: number;
  @FilterableField()  priority!: number;
  @FilterableField({ nullable: true })  createdBy?: string;
  @FilterableField({ nullable: true })  updatedBy?: string;}

SubTaskDTO

sub-task/sub-task.dto.ts

import { FilterableField, IDField, KeySet, Relation } from '@nestjs-query/query-graphql';import { ObjectType, ID, GraphQLISODateTime } from '@nestjs/graphql';import { TodoItemDTO } from '../../todo-item/dto/todo-item.dto';
@ObjectType('SubTask')@KeySet(['id'])// disable the remove because a sub task cannot exist without a todoitem@Relation('todoItem', () => TodoItemDTO, { disableRemove: true })export class SubTaskDTO {  @IDField(() => ID)  id!: string;
  @FilterableField()  title!: string;
  @FilterableField({ nullable: true })  description?: string;
  @FilterableField()  completed!: boolean;
  @FilterableField(() => GraphQLISODateTime)  createdAt!: Date;
  @FilterableField(() => GraphQLISODateTime)  updatedAt!: Date;
  @FilterableField({ nullable: true })  createdBy?: string;
  @FilterableField({ nullable: true })  updatedBy?: string;}

Many To Many Example

In this example, we'll add tags to todoItems by storing an array of tag references on the todoItems.

TodoItemEntity

todo-item/todo-item.entity.ts

import { Prop, modelOption, Ref } from '@typegoose/typegoose';import { Base } from '@typegoose/typegoose/lib/defaultClasses';
@modelOptions({ schemaOptions: { timestamps: true } })export class TodoItemEntity extends Base {  @Prop({ required: true })  title!: string;
  @Prop()  description?: string;
  @Prop({ required: true })  completed!: boolean;
  @Prop({ default: Date.now })  createdAt!: Date;
  @Prop({ default: Date.now })  updatedAt!: Date;
  @Prop({ ref: () => TagEntity })  tags!: Ref<TagEntity>[];
  @Prop({ default: 0 })  priority!: number;
  @Prop()  createdBy?: string;
  @Prop()  updatedBy?: string;
  public get id(): string {    // eslint-disable-next-line no-underscore-dangle    return this._id.toHexString();  }}

TagEntity

tag/tag.entity.ts

import { Base } from '@typegoose/typegoose/lib/defaultClasses';import { Prop, modelOptions, Ref } from '@typegoose/typegoose';import { Types } from 'mongoose';import { TodoItemEntity } from '../todo-item/todo-item.entity';
@modelOptions({  schemaOptions: {    timestamps: true,    collection: 'tags',    toObject: { virtuals: true },  },})export class TagEntity implements Base {  _id!: Types.ObjectId;
  id!: string;
  @Prop({ required: true })  name!: string;
  @Prop()  createdAt!: Date;
  @Prop()  updatedAt!: Date;
  @Prop()  createdBy?: string;
  @Prop()  updatedBy?: string;
  @Prop({    ref: 'TodoItemEntity',    localField: '_id',    foreignField: 'tags',  })  todoItems?: Ref<TodoItemEntity>[];}

Now that we have the relationship defined, we can add the @Connection to our DTOS

TodoItemDTO

todo-item/todo-item.dto.ts

import { FilterableField, IDField, KeySet, Connection } from '@nestjs-query/query-graphql';import { ObjectType, ID, GraphQLISODateTime, Field } from '@nestjs/graphql';import { TagDTO } from '../../tag/dto/tag.dto';
@ObjectType('TodoItem')@KeySet(['id'])@Connection('tags', () => TagDTO)export class TodoItemDTO {  @IDField(() => ID)  id!: string;
  @FilterableField()  title!: string;
  @FilterableField({ nullable: true })  description?: string;
  @FilterableField()  completed!: boolean;
  @FilterableField(() => GraphQLISODateTime)  createdAt!: Date;
  @FilterableField(() => GraphQLISODateTime)  updatedAt!: Date;
  @Field()  age!: number;
  @FilterableField()  priority!: number;
  @FilterableField({ nullable: true })  createdBy?: string;
  @FilterableField({ nullable: true })  updatedBy?: string;}

TagDTO

tag/tag.dto.ts

import { FilterableField, IDField, KeySet, Connection } from '@nestjs-query/query-graphql';import { ObjectType, ID, GraphQLISODateTime } from '@nestjs/graphql';import { TodoItemDTO } from '../../todo-item/dto/todo-item.dto';
@ObjectType('Tag')@KeySet(['id'])// disable update and remove since it is a virtual in the entity@Connection('todoItems', () => TodoItemDTO, { disableUpdate: true, disableRemove: true })export class TagDTO {  @IDField(() => ID)  id!: string;
  @FilterableField()  name!: string;
  @FilterableField(() => GraphQLISODateTime)  createdAt!: Date;
  @FilterableField(() => GraphQLISODateTime)  updatedAt!: Date;
  @FilterableField({ nullable: true })  createdBy?: string;
  @FilterableField({ nullable: true })  updatedBy?: string;}