Laravel 5.5雄辩的WhenLoaded关系 [英] Laravel 5.5 Eloquent WhenLoaded relationship

问题描述

在条件关系下的 Laravel 5.5文档中. ，它说

whenLoaded方法可用于有条件地加载关系

whenLoaded method may be used to conditionally load a relationship

我尝试使用自己的代码

public function toArray($request)
{
    return [
        'id' => $this->id,
        'name' => $this->name,
        'email' => $this->email,
        'roles' => Role::collection($this->whenLoaded('roles')),
        'remember_token' => $this->remember_token,
    ];
}

根据文档，由于尚未加载关系，因此将角色密钥从资源响应中完全删除之后再发送给客户端.

According to the documentation, the roles key is removed from the resource response entirely before it is sent to the client because the relationship hasn't been loaded.

如何加载关系?如何确定是否加载了关系?在这种情况下，如何加载Role(模型)?

How do I load a relationship? How do I determine if a relationship is loaded? In this case how do I load Role (model)?

推荐答案

急切加载

雄辩者可以在查询父模型时急于加载"关系.

Eloquent can "eager load" relationships at the time you query the parent model.

$user = App\User::with('roles')->find($id);

懒惰加载

要在已获取父模型后急于加载关系

To eager load a relationship after the parent model has already been retrieved

$user->load('roles');

加载缺少的关系

仅在尚未加载关系时加载

To load a relationship only when it has not already been loaded

$user->loadMissing('roles');

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