无法从对象 Laravel 中检索字段值
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unable to retrieve field values from object laravel
提问by arrowill12
I am trying to use eloquent relationships to retrieve some data from my DB. I am running into an issue when trying to get specific fields rather than the full object. Here is some of my code.
我正在尝试使用雄辩的关系从我的数据库中检索一些数据。尝试获取特定字段而不是完整对象时遇到问题。这是我的一些代码。
Controller:
控制器：
public function getHosts($table = null)
{
foreach (Hosts::all() as $host)
{
echo $host->physical_machine_name;
echo $host->app->id;
}
}
models:
楷模：
class Hosts extends Eloquent
{
protected $connection = 'mysql_2';
protected $table = 'hosts';
public $timestamps = false;
public function app(){
return $this->hasMany('Apps', 'os_instance_name')->orWhere('os_instance_name', $this->os_instance_name);
}
}
class Apps extends Eloquent
{
protected $connection = 'mysql_2';
protected $table = 'app_instances';
public $timestamps = false;
public function host()
{
return $this->belongsTo('Hosts','os_instance_name')->orWhere('os_instance_name', $this->os_instance_name);
}
}
I am not able to get the id of the app to display but when I remove the '->id' specifier i am able to get a json object containing all of the fields. Why is this happening?
我无法获取要显示的应用程序的 id，但是当我删除 '->id' 说明符时，我可以获得一个包含所有字段的 json 对象。为什么会这样？
I should also note that the $host->physical_machine_nameworks fine.
我还应该注意到$host->physical_machine_name效果很好。
this is the error I receive:
这是我收到的错误：
Undefined property: Illuminate\Database\Eloquent\Collection::$id
I am also unable to use eager loading because I am using custom foreign keys in my relationships.
我也无法使用预先加载，因为我在我的关系中使用了自定义外键。
回答by Sergiu Paraschiv
You are defining appsas a hasManyrelationship. This means appswill be a collection of entities, not a single one, hence the Illuminate\Database\Eloquent\Collectioninstance, as Laravel uses this class for lists of entities populated by Eloquent.
Being a collection of entities you won't have any properties of the Appentity on it.
你定义apps为一种hasMany关系。这意味着apps将是实体的集合，而不是单个实体，因此是Illuminate\Database\Eloquent\Collection实例，因为 Laravel 将此类用于 Eloquent 填充的实体列表。作为实体的集合，您不会拥有该App实体的任何属性。
Instead of echo $host->app->id;you can
而不是echo $host->app->id;你可以
foreach($host->app as $app) {
echo $app->id;
}
