Laravel-5.8：试图获取非对象的属性“display_name”

Question

当我尝试评估来自类别模型的数据时，我在 Laravel 中收到“试图获取非对象的属性‘display_name’”错误。

我有 2 个模型：Post 和 Category；我有相应的表格：

Posts('id', 'title', 'body', 'cover_image')

和

Categories('id', 'display_name','name', 'key).

数据透视表是：category_post

这是我的帖子模型：

namespace App;

use Illuminate\Database\Eloquent\Model;

class Post extends Model

{

    //Table Name

    protected $table = 'posts';

    //Model Relationships

    public function tag(){

        return $this->belongsToMany('App\Tag', 'id');

    }

    public function category() {

        return $this->belongsTo('App\Category','id');

    }

}

这是我的类别模型：

namespace App;

use Illuminate\Database\Eloquent\Model;

class Category extends Model

{

    protected $table = 'categories';

//Model Relationships

    public function post() 

    {

        return $this->belongsTo('App\Post', 'id');

    }

}

另外，这是我的 PagesController：

namespace App\Http\Controllers;

use Illuminate\Http\Request;

use App\Post;

class PagesController extends Controller

{

    public function index()

    {

        if ( !is_null(Post::class) ) {    

            $posts = Post::latest()->with('category')->paginate(5);

            return view('pages.index')->with(['posts' => $posts]);

        }

        else {

            return view('pages.empty');

        }

    }

这是我的刀片文件：

@if(count($posts) > 0)

   @foreach($posts as $post)

      <span> <i class="fa fa-folder-open"></i> {{ $post->category->display_name }} </span>

   @endforeach

@endif

Answer 1

问题是你没有在你的帖子表中保存CATEGORY_ID，保存好类别 ID 并尝试这样：更新 POST 模型：namespace App;use Illuminate\Database\Eloquent\Model;class Post extends Model{&nbsp; &nbsp; //Table Name&nbsp; &nbsp; protected $table = 'posts';&nbsp; &nbsp; // Setup fields of table "posts"&nbsp; &nbsp; protected $fillable = ['id', 'title', 'body', 'cover_image','category_id'];&nbsp; &nbsp; //Model Relationships&nbsp; &nbsp; public function tag(){&nbsp; &nbsp; &nbsp; &nbsp; return $this->belongsToMany('App\Tag', 'id');&nbsp; &nbsp; }&nbsp; &nbsp; // Relation category to foreign key&nbsp;&nbsp; &nbsp; public function category() {&nbsp; &nbsp; &nbsp; &nbsp; return $this->belongsTo('App\Category','category_id');&nbsp; &nbsp; }}类别模型namespace App;use Illuminate\Database\Eloquent\Model;class Category extends Model{&nbsp; &nbsp; protected $table = 'categories';&nbsp; &nbsp; // Setup fields of table "category"&nbsp; &nbsp; protected $fillable = ['id', 'display_name', 'name', 'key'];&nbsp; &nbsp; //Model Relationships&nbsp; &nbsp; public function posts()&nbsp;&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; return $this->hasMany('App\Post');&nbsp; &nbsp; }}看法@if(count($posts) > 0)&nbsp; &nbsp;@foreach($posts as $post)&nbsp; &nbsp; &nbsp; <span> <i class="fa fa-folder-open"></i> {{ $post->category->display_name }} </span>&nbsp; &nbsp;@endforeach@endif移民帖 - 外键 category_idSchema::create('posts', function (Blueprint $table) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; // Your other fields.....&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; // You must setup category like this&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; $table->integer('category_id')->nullable()->unsigned();&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; $table->foreign('category_id')->references('id')->on('categories')->onUpdate('cascade')->onDelete('cascade');&nbsp; &nbsp; &nbsp; &nbsp; });控制器namespace App\Http\Controllers;use Illuminate\Http\Request;use App\Post;class PagesController extends Controller{&nbsp; &nbsp; public function index()&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; $posts = Post::all();&nbsp; &nbsp; &nbsp; &nbsp; if (!empty($posts)) {&nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; // Please let me know this test&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; dd($posts[0]->category->display_name);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return view('pages.index', ['posts' => $posts]);&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; else {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return view('pages.empty');&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; }

Answer 2

我认为您post()在Category模型中的方法有误。尝试像这样修改这个方法：类别型号：public&nbsp;function&nbsp;post()&nbsp; {&nbsp;&nbsp;&nbsp;&nbsp;return&nbsp;$this->hasMany('App\Post',&nbsp;'id');}来源：Eloquent-relationship 一对多