为什么 Laravel / Eloquent 的 fresh 函数返回一个对象，但调用它的属性返回 0？

我的代码有一个地址Model在 Eloquent 中，它看起来像这样：

值得注意的是：我的所有模型都使用 uuid 作为主键，它是由 MySQL 数据库中的触发器生成的。这本身就很有效。

<?php namespace App\Models;

    use Illuminate\Database\Eloquent\Model;

    class Address extends Model {    
        protected $table = 'Addresses';
        protected $fillable = ['uuid', 'zipCode', 'houseNumber'];
        protected $primaryKey = 'uuid';
        public $incrementing = false; //<- without this it returns 0, with it returns null
    }

在我的控制器中，我创建了一个函数来创建一个新地址，该地址从触发器获取其 uuid（如上所述）。为了将这个 uuid（这也是一个外键）传递给我的用户，我尝试调用fresh();

<?php
public function store(Request $request) {
    $input = $request->all();
    try {
        $address = Address::create($input);
        // Call fresh to also get the trigger generated uuid primaryKey
        $address = $address->fresh(); //bug!!!
        //$address = Address::query()->where('zipCode', '=', $address->zipCode)->where('houseNumber', '=', $address->houseNumber)->first(); //works, but is not as nice
    }  catch (\exception $e) {
        $response['error'] = $e->getMessage();
        return response($response, 400);
    }
}

在重新加载（并获取我的 uuid）之前，$address对象等于

object(App\Models\Address)#186 (23) {
  ["table":protected]=>
  string(9) "Addresses"
  ["fillable":protected]=>
  array(3) {
    [0]=>
    string(4) "uuid"
    [1]=>
    string(7) "zipCode"
    [2]=>
    string(11) "houseNumber"
  }
  ["primaryKey":protected]=>
  string(4) "uuid"
  ["incrementing"]=>
  bool(false)
  ["connection":protected]=>
  NULL
  ["keyType":protected]=>
  string(3) "int"
  ["perPage":protected]=>
  int(15)
  ["timestamps"]=>
  bool(true)
  ["attributes":protected]=>
  array(4) {
    ["zipCode"]=>
    string(6) "4651ZX"
    ["houseNumber"]=>
    string(2) "34"
    ["updated_at"]=>
    string(19) "2016-11-28 23:13:47"
    ["created_at"]=>
    string(19) "2016-11-28 23:13:47"
  }
  ["original":protected]=>
  array(4) {
    ["zipCode"]=>
    string(6) "4651ZX"
    ["houseNumber"]=>
    string(2) "34"
    ["updated_at"]=>
    string(19) "2016-11-28 23:13:47"
    ["created_at"]=>
    string(19) "2016-11-28 23:13:47"
  }
  ["relations":protected]=>
  array(0) {
  }
  ["hidden":protected]=>
  array(0) {
  }
  ["visible":protected]=>
  array(0) {
  }
  ["appends":protected]=>
  array(0) {
  }
  ["guarded":protected]=>
  array(1) {
    [0]=>
    string(1) "*"
  }
  ["dates":protected]=>
  array(0) {
  }
  ["dateFormat":protected]=>
  NULL
  ["casts":protected]=>
  array(0) {
  }
  ["touches":protected]=>
  array(0) {
  }
  ["observables":protected]=>
  array(0) {
  }
  ["with":protected]=>
  array(0) {
  }
  ["exists"]=>
  bool(true)
  ["wasRecentlyCreated"]=>
  bool(true)
}

如果在我的地址模型中$incrementing = false;已定义，我称$address = $address->fresh();现在$address对象相等NULL

如果我在地址模型中省略$incrementing = false;，我打电话给$address = $address->fresh();现在$address对象相等

object(App\Models\Address)#195 (23) {
  ["table":protected]=>
  string(9) "Addresses"
  ["fillable":protected]=>
  array(3) {
    [0]=>
    string(4) "uuid"
    [1]=>
    string(7) "zipCode"
    [2]=>
    string(11) "houseNumber"
  }
  ["primaryKey":protected]=>
  string(4) "uuid"
  ["connection":protected]=>
  NULL
  ["keyType":protected]=>
  string(3) "int"
  ["perPage":protected]=>
  int(15)
  ["incrementing"]=>
  bool(true)
  ["timestamps"]=>
  bool(true)
  ["attributes":protected]=>
  array(5) {
    ["uuid"]=>
    string(36) "0e85ea0c-b5c0-11e6-9c20-002590f967ca"
    ["zipCode"]=>
    string(6) "4651ZX"
    ["houseNumber"]=>
    string(2) "34"
    ["updated_at"]=>
    string(19) "2016-11-28 23:11:56"
    ["created_at"]=>
    string(19) "2016-11-28 23:11:56"
  }
  ["original":protected]=>
  array(5) {
    ["uuid"]=>
    string(36) "0e85ea0c-b5c0-11e6-9c20-002590f967ca"
    ["zipCode"]=>
    string(6) "4651ZX"
    ["houseNumber"]=>
    string(2) "34"
    ["updated_at"]=>
    string(19) "2016-11-28 23:11:56"
    ["created_at"]=>
    string(19) "2016-11-28 23:11:56"
  }
  ["relations":protected]=>
  array(0) {
  }
  ["hidden":protected]=>
  array(0) {
  }
  ["visible":protected]=>
  array(0) {
  }
  ["appends":protected]=>
  array(0) {
  }
  ["guarded":protected]=>
  array(1) {
    [0]=>
    string(1) "*"
  }
  ["dates":protected]=>
  array(0) {
  }
  ["dateFormat":protected]=>
  NULL
  ["casts":protected]=>
  array(0) {
  }
  ["touches":protected]=>
  array(0) {
  }
  ["observables":protected]=>
  array(0) {
  }
  ["with":protected]=>
  array(0) {
  }
  ["exists"]=>
  bool(true)
  ["wasRecentlyCreated"]=>
  bool(false)
}

这就是我想要的！

但当我一打电话$address['uuid'] or $address->uuid它返回int(0)（不为空）

我必须填写castsuuid 为字符串的数组。