Loopback 4 - HasMany relation included in fields - postgresql

Question

I am trying to setup the relation HasMany with the new Loopback 4 framework.
I have the following model:
import {Entity, model, property, belongsTo, hasMany} from
'#loopback/repository';
import {User} from "./user.model";
import {OrderProduct} from "./order-product.model";
#model({
name: 'sales_order'
})
export class Order extends Entity {
#property({
type: 'number',
id: true,
required: true,
})
id: number;
#property({
type: 'number',
required: true,
})
total_amount: number;
#belongsTo(() => User)
user_id: number;
#hasMany(() => OrderProduct, {keyTo: 'order_id'})
products?: OrderProduct[];
constructor(data?: Partial<Order>) {
super(data);
}
}
And the repository as follow:
import {DefaultCrudRepository, repository, HasManyRepositoryFactory, BelongsToAccessor} from '#loopback/repository';
import {Order, OrderProduct, User} from '../models';
import {DbDataSource} from '../datasources';
import {inject, Getter} from '#loopback/core';
import {OrderProductRepository} from "./order-product.repository";
import {UserRepository} from "./user.repository";
export class OrderRepository extends DefaultCrudRepository<
Order,
typeof Order.prototype.id
> {
public readonly user: BelongsToAccessor<
User,
typeof Order.prototype.id
>;
public readonly products: HasManyRepositoryFactory<
OrderProduct,
typeof Order.prototype.id
>;
constructor(
#inject('datasources.db') dataSource: DbDataSource,
#repository.getter(OrderProductRepository)
getOrderProductRepository: Getter<OrderProductRepository>,
#repository.getter('UserRepository')
userRepositoryGetter: Getter<UserRepository>,
) {
super(Order, dataSource);
this.products = this._createHasManyRepositoryFactoryFor(
'products',
getOrderProductRepository,
);
this.user = this._createBelongsToAccessorFor(
'user_id',
userRepositoryGetter,
);
}
}
When I do for example a get on orders, I have the errors: 500 error: column "products" does not exist and in digging a bit more, I can see that the SQL is trying to retrieve the fields products where it is just a relation.
Anybody have an idea if I am doing something wrong?
I am using pg as DB.

Answer 1

I believe this is a bug in LoopBack 4. When you decorate a class property with #hasMany, the decorator defines a model property under the hood. See here:
export function hasMany<T extends Entity>(
targetResolver: EntityResolver<T>,
definition?: Partial<HasManyDefinition>,
) {
return function(decoratedTarget: Object, key: string) {
property.array(targetResolver)(decoratedTarget, key);
// ...
};
}
When the connector is querying the database, it's trying to include the column products in the query, because it thinks products is a property.
The problem is already tracked by https://github.com/strongloop/loopback-next/issues/1909, please consider upvoting the issue and joining the discussion.