环回 4 - 字段中包含的 HasMany 关系

Question

我正在尝试使用新的 Loopback 4 框架设置 HasMany 关系。我有以下型号：

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);
  }
}

存储库如下：

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,
    );
  }
}

例如，当我执行订单时，出现错误：500 error: column "products" does not exist 并且在进一步挖掘时，我可以看到 SQL 正在尝试检索字段 products 它只是一个关系。如果我做错了什么，有人知道吗？我正在使用 pg 作为数据库。

Answer 1

我认为这是 LoopBack 4 中的一个错误。当您用 @hasMany 装饰 class 属性时，装饰器在底层定义了一个模型属性。见 here:

export function hasMany<T extends Entity>(
  targetResolver: EntityResolver<T>,
  definition?: Partial<HasManyDefinition>,
) {
  return function(decoratedTarget: Object, key: string) {
    property.array(targetResolver)(decoratedTarget, key);

    // ...
  };
}

当连接器查询数据库时，它试图在查询中包含列 products，因为它认为 products 是属性.

问题已被 https://github.com/strongloop/loopback-next/issues/1909 跟踪，请考虑提出问题并加入讨论。

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