HasMany

Below is how you can define a HasMany relationship.

@Definition()
export class Store {
  @Id()
  id: ObjectId;
 
  @Property()
  name: string;
 
  @HasMany(() => Product, {
    to: 'storeId',
    allowCreateWithin: true,
    allowFindAll: true,
    allowPaginate: true,
  })
  products: Product[];
}
 
@Definition()
export class Product {
  @Id()
  id: ObjectId;
 
  @Property()
  name: string;
 
  @Property({ type: () => GraphQLObjectId })
  storeId: ObjectId;
}

In the above example, we have defined a HasMany relationship between Store and Product. This means that a Store can have many Products. Because of that we have to define a storeId property on the Product class. This is the foreign key that will be used to identify which Store a Product belongs to.

Create API

mutation {
  createStore(input: {
    name: "Awsome Store 1",
    products: [
      { name: "Product 1" }
      { name: "Product 2" }
    ]
  }) {
    id
    name
    products {
      id
      name
    }
    paginateProducts {
      docs {
        id
        name
      }
      totalDocs
    }
  }
}

Resolve fields

As you can see in the above example, we can get the products and paginateProducts fields on the Store type. You can suppress these fields by setting allowFindAll and allowPaginate to false in the options or just omit them.

Ensure relationship

By default, you cannot remove a Store if it has any Products. To allow remove that, you can set skipRelationCheckOnRemove to true in the options;

Multi-level support

Create API also supports multi-level relationship. For example, if you define Product has many Variant, then you can create a Store with Products and Variants in one go. Similar to HasMany, BelongsTo, HasOne, and ReferencesMany, the Create API also supports multi-level relationships.