Laravel 5.5 - 多态关系

Question

假设我在 Laravel 中有四个表（模型）：

User.php

id - integer
name - string

---

<?php

namespace App;

use Illuminate\Notifications\Notifiable;
use Illuminate\Foundation\Auth\User as Authenticatable;

class User extends Authenticatable
{
    use Notifiable;

    /**
     * The attributes that are mass assignable.
     *
     * @var array
     */
    protected $fillable = [
        'name', 'email', 'password', 'token_id'
    ];

    /**
     * The attributes that should be hidden for arrays.
     *
     * @var array
     */
    protected $hidden = [
        'password', 'remember_token',
    ];

    public function embeds()
    {
        return $this->hasManyThrough('App\Post', 'App\Role');
    }
}

UserRoles.php

id - integer
user_id - integer
role_id - integer

---

<?php

namespace App;

use Illuminate\Database\Eloquent\Relations\Pivot;

class UserRoles extends Pivot
{
    protected $guarded = [];

    public function role()
    {
        return $this->belongsTo(Role::class);
    }

    public function user()
    {
        return $this->belongsToMany(User::class, 'user_id');
    }
}

Role.php

id - integer
name - string

---

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class Role extends Model
{
    /**
     * Don't auto-apply mass assignment protection.
     *
     * @var array
     */
    protected $guarded = [];

    public function roles()
    {
        return $this->belongsToMany(UserRoles::class);
    }
}

Post.php

id - integer
title - string
body - text
role_id - integer

---

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class Post extends Model
{
    /**
     * Don't auto-apply mass assignment protection.
     *
     * @var array
     */
    protected $guarded = [];
}

如您所见，UserRoles 是将Users 与Roles 连接起来的数据透视表。而Posts 只能与一个角色相关联（技术规范要求）。

如何在 Eloquent 中建立关系，以便我可以让用户通过分配给他们的 Roles 获得他们可以看到的每一个 Post？

我已经修改了 Laravel 关系文档的查看，并且我看到了 Many-to-Many 多态关系，但似乎我不断得到：SQLSTATE[42S02]: Base table or view not found: 1146 Table 或某种形式。

我做错了什么？

Answer 1

嗯，数据透视表确实需要模型。您需要四个表和三个模型。

你几乎把桌子弄对了。只需将UserRole 表重命名为role_user 即可关注Laravel convention。

role_user 表由相关模型名称的字母顺序派生而来，包含 user_id 和 role_id 列。

以下是您应该如何设置模型：

// User.php

    public function roles()
    {
        return $this->belongsToMany(Role::class);
    }

    public function posts()
    {
        return $this->hasManyThrough(Post::class, Role::class);
    }

// Role.php

    public function users()
    {
        return $this->belongsToMany(User::class);
    }


    public function posts()
    {
        return $this->hasMany(Post::class);
    }