laravel - `morphTo` 方法的第一个参数的用例是什么？

Question

根据这个问题，在 Laravel 上使用自定义方法名定义多态关系时，morphTo方法的 name 参数不能按预期工作，我们假设一个简单的多态表结构：

posts
    id - integer
    name - string

users
    id - integer
    name - string

images
    id - integer
    url - string
    imageable_id - integer
    imageable_type - string

这个模型结构：

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class Image extends Model
{
    // ...

    // It doesn't work as expected
    public function picturable1()
    {
        return $this->morphTo('imageable');
    }

    // It doesn't work as expected
    public function picturable2()
    {
        return $this->morphTo('imageable', 'imageable_type', 'imageable_id');
    }

    // It works unexpectedly
    public function picturable3()
    {
        return $this->morphTo(null, 'imageable_type', 'imageable_id');
    }
}

加载这些关系时：

$image = \App\Image::with('picturable1')->find(1);
$image->picturable1; // exists and returns null but imageable instance was expected
$image->imageable;   // returns imageable instance unexpectedly

$image = \App\Image::with('picturable2')->find(1);
$image->picturable2; // exists and returns null but imageable instance was expected
$image->imageable;   // returns imageable instance unexpectedly

$image = \App\Image::with('picturable3')->find(1);
$image->picturable3; // returns imageable instance as expected
$image->imageable;   // doesn't exists as expected

所以问题是，方法的名称参数的用例是什么morphTo？以及像上面的示例一样自定义关系名称的正确方法是什么？

标签： laraveleloquenteloquent-relationshippolymorphic-relationship

Answer 1

我猜该name参数允许您自定义将存储相关模型的属性的名称。因此，在控制器中，您应该指定您期望的名称作为关系：

    public function picturable1()
    {
        return $this->morphTo('picturable1', 'imageable_type', 'imageable_id');
        // or return $this->morphTo(null, 'imageable_type', 'imageable_id');
    }

    public function picturable2()
    {
        return $this->morphTo('picturable2', 'imageable_type', 'imageable_id');
        // or return $this->morphTo(null, 'imageable_type', 'imageable_id');
    }