Laravel 关系错误：未定义属性：第 1 行的 Illuminate\Database\Eloquent\Collection::$id
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Laravel relationship error: Undefined property: Illuminate\Database\Eloquent\Collection::$id on line 1
提问by omrakhur
I have two models Companyand Employee, with corresponding tables in MySQL, companies, and employees.
我有两个模型Company和Employee，在 MySQL 中有相应的表companies， 和employees。
I have these Many-to-One relationships defined:
我定义了这些多对一关系：
In the Companymodel:
在Company模型中：
public function employees(){
return $this->hasMany('App\Employee','company');
}
In the Employeemodel:
在Employee模型中：
public function company(){
return $this->belongsTo('App\Company','company');
}
companyabove in the methods is an unsigned integer foreign key present in the employeestable.
company上面的方法是employees表中存在的无符号整数外键。
In tinker I have tried $company->employees;, which returns a list of all the employees in the selected company. However, when I do $company->employees->idto get the IDs of all the employees only and not the other rows, it gives me the error:
在 tinker 我已经尝试过$company->employees;，它返回所选公司中所有员工的列表。但是，当我$company->employees->id只获取所有员工的 ID 而不是其他行时，它给了我错误：
PHP error: Undefined property: Illuminate\Database\Eloquent\Collection::$id on line 1
采纳答案by Neat
Well $company->employeesreturns a collection, ->idis not a property in the collection, thats why you get the error.
那么$company->employees返回一个集合，->id它不是集合中的一个属性，这就是你得到错误的原因。
If you want to retrieve an array containing all the id's of your employees you might do this:
如果您想检索一个包含所有员工 ID 的数组，您可以这样做：
$company->employees()->lists('id');
If you're reading this and using laravel ^5.3.*then the answer would be:
如果您正在阅读本文并使用 laravel，^5.3.*那么答案将是：
$company->employees()->pluck('id');
This would return a collection with all id's, if you want it to be an array you can chain the ->toArray()behind it.
这将返回一个包含所有 id 的集合，如果您希望它是一个数组，您可以将->toArray()其链接到后面。
