Laravel验证请求 - 不要让特定字符串通过

Question

我已经在Angular JS 2中写了一个表单，它发布到Laravel后端API并在那里得到验证..一切正常但是如果一个字段留空，那么当用户发布表单时它仍然写入数据库为＆＃39; undefined＆＃39;

无论如何使用laravels规则将此字符串分类为空？我当前的规则文件如下所示：

        <?php

        namespace App\Http\Requests;

        use App\Http\Requests\Request;

        class ContactFormRequest extends Request
        {
            /**
             * Determine if the user is authorized to make this request.
             *
             * @return bool
             */

            public function authorize()
            {
                return true;
            }

            public function rules()
            {
                return [
                    "name"    =>      "required|between:5,60",
                    "email"   =>      "required|between:5,60",
                    "website" =>      "required|between:5,60",
                ];
            }

            public function messages()
            {
                return [
                    'name.between'     => 'The :attribute must be between :min - :max.',
                    'name.required'    => 'The :attribute is required!',
                    'email.between'    => 'The :attribute must be between :min - :max.',
                    'email.required'   => 'The :attribute is required!',
                    'website.between'  => 'The :attribute must be between :min - :max.',
                    'website.required' => 'The :attribute is required!',
                ];
            }
        }