laravel - 调用模型 [App\Models\Announcement] 上的未定义关系 [公司]。我该如何解决这个问题

Question

我有 2 张桌子：公告和公司。company_id 是公告表上的外键。

我有这样的控制器设置：

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;
use App\Http\Controllers\Controller;
use App\Models\Announcement;
use App\Models\Company;

class AnnouncementController extends Controller
{
public function upcomingIssues()
    {
        $announcement = Announcement::orderBy('id','desc')->with('companies')->get();

        return view('pages.upcoming-issues',compact('announcement'));

    }
}

公告模型如下：

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Announcement extends Model
{
    protected $table = 'announcements';
    public function company()
    {
        return $this->belongsTo(Company::class, 'company_id');
    }

    // Usage: $announcement->company
    public function getCompanyAttribute()
    {
        return $this->companies->where('id','company_id')->get();
    }
}

公司模式如下

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Company extends Model
{
    protected $table = 'companies';

    public function announcement()
    {
        return $this->hasMany(Announcement::class, 'company_id');
    }
}

最后查看表格如下：

<table class="table table-striped">
      <thead>
        <tr>
          <th scope="col">#</th>
          <th scope="col">Company</th>
        </tr>
      </thead>
      <tbody>
        @foreach($announcement as $announce)
        <tr>
          <th>{{ $loop->iteration }}</th>
          <td>{{ $announce->company }}</td>     
        </tr>
        @endforeach
        </tr>
      </tbody>
    </table>

当我尝试访问此页面时，我收到以下消息“

调用模型 [App\Models\Announcement] 上的未定义关系 [公司]。

"

Answer 1

您必须通过两种方法来解决此问题。一种是在公告模型中更改关系名称

public function company()
{
     return $this->belongsTo(Company::class, 'company_id');
}

到

public function companies()
{
        return $this->belongsTo(Company::class, 'company_id');
}

或保持关系名称不变并在控制器中更改

public function upcomingIssues()
{
        $announcement = Announcement::orderBy('id','desc')->with('companies')->get();

        return view('pages.upcoming-issues',compact('announcement'));

}

到

public function upcomingIssues()
{
        $announcement = Announcement::orderBy('id','desc')->with('company')->get();

        return view('pages.upcoming-issues',compact('announcement'));

}

并且如果您使用公司作为关系名称，请更改

public function getCompanyAttribute()
{
        return $this->companies->where('id','company_id')->get();
}

到

public function getCompanyAttribute()
{
        return $this->company->where('id','company_id')->get();
}