环回：如何在 afterRemote 中访问关系

Question

我为仓库模型设置了以下 afterRemote 方法：

  Depot.afterRemote('find', function(context, depots, next) {

        context.result.forEach(depot => {
          console.log(depot.drivers);
          depot.address = depot.street_name + ' ' + depot.door_number;
          depot.driver_count = depot.drivers.length;
        });

        next()
      })

在 json 响应中 depot.drivers 包含正确的数据。

然而，当我尝试在上述方法中访问 depot.drivers 时，我得到了一些奇怪的输出：

{ [Function: f]
  _receiver: { postal_code: '1216BS',
     door_number: '3',
     street_name: 'Straat naam',
     city: 'Hilversum',
     lat: null,
     lng: null,
     created: 2018-04-03T01:49:12.000Z,
     id: 23,
     distributor_id: 2,
     distributor: { sys_id: 1,
        name: 'distributeur naam',
        contact_person: 'Persoon B',
        phone: '000-000000',
        email: 'info@d.nl',
        created: 2018-03-06T00:22:33.000Z,
        id: 2 },
     drivers: List [] },
  _scope: { where: { hub_id: 23 } },
  _targetClass: 'driver',
  find: [Function],
  getAsync: [Function],
  build: [Function: bound method],
  create: [Function: bound method],
  updateAll: [Function: updateAll],
  destroyAll: [Function: destroyAll],
  findById: [Function: bound method],
  findOne: [Function: findOne],
  count: [Function: count],
  destroy: [Function: bound method],
  updateById: [Function: bound method],
  exists: [Function: bound method] }

我最终想添加一个 depot.drivers_count 属性，这样我就可以在前端显示连接到特定站点的驱动程序数量 table。

有人知道怎么做吗？

Answer 1

看起来数据没有转换为 JSON。

我会试试这个：

context.result.forEach(depot => {
      depot = depot.toJSON();
      console.log(depot.drivers);
      depot.address = depot.street_name + ' ' + depot.door_number;
      depot.driver_count = depot.drivers.length;
 });

Answer 2

在 Loopback 中，可以使用回调函数访问每个模型关系，因为 i/o 是异步的。这样做：

depot.drivers((err, drivers) => {
  // handle the error
  // do something with the drivers
})

您还可以使用驱动程序模型操作挂钩来跟踪数据更改并更新相关的 Depot.drivers_count 属性:

Driver.observe('after save', function(ctx, next) {
  // ctx.instance is the created or updated object
  if (ctx.isNewInstance) {
    // A new record was saved
    // Implementation depends on your models relationships
  } else {
    // A record was updated
    // Implementation depends on your models relationships
  }
  
  next()
})

Driver.observe('after delete', (ctx, next) => {
  // Implementation depends on your models relationships
  next()
})

这里有更多信息Loopback Operation hooks - After Save

环回：如何在 afterRemote 中访问关系

Loopback: How to access relationship in an afterRemote

loopbackjs