lavarel初学者：通过模型控制性别

Question

index文件:<td>{{ $student->sex($student->sex) }}</td>

模型文件：Student.php

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class Student extends Model
{
   //通过模型处理性别，先定义三个常量
   const SEX_UN = 10; //未知
   const SEX_BOY = 20;  //男
   const SEX_GIRL = 30;   //女

   protected $table = 'student';

   protected $fillable = ['name','age','sex']; //允许批量赋值

   public $timestamps = true;

   protected function getDateFormat()
   {
       return time();
   }

   protected function asDateTime($val)
   {
       return $val;
   }

   //定义一个方法sex
   public function sex($ind = null)
   {
       $arr = [
           self::SEX_UN => '未知',
           self::SEX_BOY => '男',
           self::SEX_GIRL => '女',
       ];

       if( $ind !== null ){
           return array_key_exists($ind, $arr) ? $arr[$ind] : $arr[self::SEX_UN];
       }

       return $arr;
   }
}

最后index显示报错

ErrorExceptionin helpers.php line 529:                            htmlentities() expects parameter 1 to be string, array given                        

in helpers.php line 529

atHandleExceptions->handleError('2', 'htmlentities() expects parameter 1 to be string, array given', 'D:\xampps\htdocs\laravel-demo\vendor\laravel\framework\src\Illuminate\Support\helpers.php', '529', array('value' => array('未知', '男', '女')))

athtmlentities(array('未知', '男', '女'), '3', 'UTF-8', false) in helpers.php line 529

ate(array('未知', '男', '女')) in d5c5164230498b21f0daeb217404370268fd2229.php line 31

atinclude('D:\xampps\htdocs\laravel-demo\storage\framework\views\d5c5164230498b21f0daeb217404370268fd2229.php') in PhpEngine.php line 42

怎么办？

Answer 1

数据是null返回了数组，页面里只能打印字符串，你给了数组，当然报错。改成默认返回未知