当我尝试评估类别模型中的数据时，在Laravel中出现“尝试获取非对象的属性'display_name'”错误。
我有2个模型：职位和类别；我有对应的表格：
Posts('id', 'title', 'body', 'cover_image')
和
Categories('id', 'display_name','name', 'key).
数据透视表为：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
更新
这些是我的迁移： 帖子表：
use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;
class CreatePostsTable extends Migration
{
/**
* Run the migrations.
*
* @return void
*/
public function up()
{
Schema::create('posts', function (Blueprint $table) {
$table->increments('id');
$table->string('title');
$table->string('slug')->nullable();
$table->mediumText('body');
$table->string('cover_image')->default('noimage.jpg')->nullable();
$table->integer('user_id');
$table->timestamps();
$table->integer('category_id')->unsigned()->nullable();
$table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
$table->foreign('category_id')->references('id')->on('categories')->onDelete('cascade');
});
}
/**
* Reverse the migrations.
*
* @return void
*/
public function down()
{
Schema::dropIfExists('posts');
}
}
我的类别表：
use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;
class CreateCategoriesTable extends Migration
{
/**
* Run the migrations.
*
* @return void
*/
public function up()
{
Schema::create('categories', function (Blueprint $table) {
$table->increments('id');
$table->string('name')->unique();
$table->string('display_name');
$table->string('description')->nullable();
$table->string('password')->nullable();
$table->timestamps();
});
}
/**
* Reverse the migrations.
*
* @return void
*/
public function down()
{
Schema::dropIfExists('categories');
}
}
预期的结果是从类别表中获取display_name并以列表方式显示它们。 这是我不断收到的错误
试图获取非对象的属性“ display_name”（视图：D：\ xampp \ htdocs \ MyProject \ resources \ views \ pages \ index.blade.php）
我试图这样称呼它：
<span> <i class="fa fa-folder-open"></i> {{ $post->category()->display_name }} </span>
但是它也不起作用。
将$ post变量转储到Controller之后：
Post {#331 ▼
#table: "posts"
#fillable: array:7 [▼
0 => "id"
1 => "title"
2 => "slug"
3 => "body"
4 => "cover_image"
5 => "user_id"
6 => "category_id"
]
+primaryKey: "id"
+timestamps: true
#connection: "mysql"
#keyType: "int"
+incrementing: true
#with: []
#withCount: []
#perPage: 15
+exists: true
+wasRecentlyCreated: false
#attributes: array:9 [▼
"id" => 1
"title" => "This is a Base Announcement"
"slug" => null
"body" => "Please feel free to delete this announcement and create a new one afterwards."
"cover_image" => "noimage.jpg"
"user_id" => 1
"created_at" => "2019-05-20 14:22:45"
"updated_at" => "2019-05-20 14:22:45"
"category_id" => null
]
#original: array:9 [▼
"id" => 1
"title" => "This is a Base Announcement"
"slug" => null
"body" => "Please feel free to delete this announcement and create a new one afterwards."
"cover_image" => "noimage.jpg"
"user_id" => 1
"created_at" => "2019-05-20 14:22:45"
"updated_at" => "2019-05-20 14:22:45"
"category_id" => null
]
#changes: []
#casts: []
#dates: []
#dateFormat: null
#appends: []
#dispatchesEvents: []
#observables: []
#relations: []
#touches: []
#hidden: []
#visible: []
#guarded: array:1 [▼
0 => "*"
]
}
答案 0 :(得分：0)
问题在于您没有将 CATEGORY_ID 保存在帖子表中，请妥善保存类别ID并尝试执行以下操作：
更新POST模型：
namespace App;
use Illuminate\Database\Eloquent\Model;
class Post extends Model
{
//Table Name
protected $table = 'posts';
// Setup fields of table "posts"
protected $fillable = ['id', 'title', 'body', 'cover_image','category_id'];
//Model Relationships
public function tag(){
return $this->belongsToMany('App\Tag', 'id');
}
// Relation category to foreign key
public function category() {
return $this->belongsTo('App\Category','category_id');
}
}
类别模型
namespace App;
use Illuminate\Database\Eloquent\Model;
class Category extends Model
{
protected $table = 'categories';
// Setup fields of table "category"
protected $fillable = ['id', 'display_name', 'name', 'key'];
//Model Relationships
public function posts()
{
return $this->hasMany('App\Post');
}
}
查看
@if(count($posts) > 0)
@foreach($posts as $post)
<span> <i class="fa fa-folder-open"></i> {{ $post->category->display_name }} </span>
@endforeach
@endif
迁移帖子-外键category_id
Schema::create('posts', function (Blueprint $table) {
// Your other fields.....
// You must setup category like this
$table->integer('category_id')->nullable()->unsigned();
$table->foreign('category_id')->references('id')->on('categories')->onUpdate('cascade')->onDelete('cascade');
});
控制器
namespace App\Http\Controllers;
use Illuminate\Http\Request;
use App\Post;
class PagesController extends Controller
{
public function index()
{
$posts = Post::all();
if (!empty($posts)) {
// Please let me know this test
dd($posts[0]->category->display_name);
return view('pages.index', ['posts' => $posts]);
}
else {
return view('pages.empty');
}
}
答案 1 :(得分：-1)
我认为您在post()模型中的Category方法中犯了一个错误。尝试像这样修改此方法：
类别模型：
public function post()
{
return $this->hasMany('App\Post', 'id');
}