Laravel验证导致对保存模型的查询异常

应用程序有两个数据库连接:

mysql_default_connection => default_database
mysql_custom_connection => custom_database

我有一些问题与Laravel unique验证。

protected $connection = 'mysql_custom_connection';
protected $table = 'aluno';
public $rules = [
    'email' => 'required|email|unique:custom_database.aluno'
];

当我尝试保存一个新模型时，唯一的规则工作，但是当从aluno检索一些模型并尝试将其保存为:

$aluno = Aluno::find(1);
$aluno->attribute = 'new value';
$aluno->save();

这日志:

SQLSTATE[42S02]: Base table or view not found: 1146 Table 'default_database.aluno' doesn't exist (SQL: select count(*) as aggregate from `aluno` where `email` = aluno3@email.com and `id` <> 50)

如果我从验证中删除unique规则，工作正常。

特别是，我不明白为什么要在Table 'default_database.aluno'中查询，因为这个数据库不是上面的模型连接。

我的连接配置

'connections' => [
    'mysql_default_connection' => [
        'driver'    => 'mysql',
        'host'      => 'localhost',
        'port'      => 3306,
        'database'  => 'default_database',
        'username'  => 'root',
        'password'  => '',
        'charset'   => 'utf8',
        'collation' => 'utf8_unicode_ci',
        'prefix'    => '',
    ],
    'mysql_custom_connection' => [
        'driver'    => 'mysql',
        'host'      => 'localhost',
        'port'      => 3306,
        'database'  => 'custom_database',
        'username'  => 'root',
        'password'  => '',
        'charset'   => 'utf8',
        'collation' => 'utf8_unicode_ci',
        'prefix'    => '',
    ],
];
'default' => 'mysql_default_connection',

aluno模型相关部分

protected $connection = 'mysql_custom_connection';
protected $table = 'aluno';
public $rules = [
    'nome' => 'required|between:5, 45',
    'email' => 'required|email|unique:custom_database.aluno|max:64'
];

此规则适用于创建新模型

    /**
 * Instantiates the validator used by the validation process, depending if the class is being used inside or
 * outside of Laravel.
 * @return 'Illuminate'Validation'Validator
 */
protected static function makeValidator($data, $rules, $customMessages, $attributeNames)
{
    return Validator::make($data, $rules, $customMessages, $attributeNames);
}

  /*
  * Hand over to the validator
  */
  $validator = self::makeValidator($data, $rules, $customMessages, $attributeNames);

 protected static function makeValidator($data, $rules, $customMessages, $attributeNames,$connection = null)
 {
     $validator = Validator::make($data, $rules, $customMessages, $attributeNames);
     if($connection !== null) {
         $validator->getPresenceVerifier()->setConnection($connection);
     }
     return $validator;
 }

 $validator = self::makeValidator($data, $rules, $customMessages, $attributeNames,$this->connection);

$rules = [
  'email' => 'required|unique:aluno'
];