Troubling to show sub-categories in the Categories Dropdown list

Question

in my code,i want to show category and sub catagory under the Category in the Products table .

Here is my categories table

1.

 public function up() { Schema::create('categories', function (Blueprint $table) {

    $table->increments('id');
    $table->integer('parent_id'); //sub category id
    $table->string('name');  
    $table->rememberToken();
    $table->timestamps();

    });
}

Here is my products table

2.

public function up()
{
    Schema::create('products', function (Blueprint $table) {
        $table->increments('id');
        $table->integer('category_id');
        $table->string('product_name');
        $table->timestamps();
    });
}

Here is my Category Model

3.Category.php

<?php
namespace App;
use Illuminate\Database\Eloquent\Model;

class Category extends Model { protected $guarded=[];

    public function products(){
        return $this->hasMany('App\Product');
    }

    public function parent(){
        return $this->belongsTo('App\Category','parent_id','id');
    }
}

Here is my Product Model

4.Product.php

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class Product extends Model
{
    public function category(){
        return $this->hasone('class::Category');
    }

}

Now here is my ProductsController.php

5.ProductsController.php

<?php
namespace App\Http\Controllers;
use App\Category;
use App\Product;
use Session;
use Illuminate\Http\Request;
class ProductsController extends Controller
{
    public  function product(){
         return view('admin.products.product');
     }


}

Here is my product.blade.php file

<form class="form-horizontal" method="post" action="{{route('add.product')}}" name="add_product" id="add_product" novalidate="novalidate">
                                @csrf

                                <div class="control-group">
                                    <label class="control-label">main Category </label>
                                    <div class="controls">
                                        <select name="category_id" id="category_id" style="width:220px;">

                                            @foreach(App\Category::all() as $cat)
                                                <option value="{{$cat->id}}" >{{ $cat->parent()->name ? $cat->parent()->name . ' -- ' : '' }}{{$cat->name}}</option>
                                            @endforeach

                                        </select>
                                    </div>
                                </div>

                                <div class="control-group">
                                    <label class="control-label">Product Name</label>
                                    <div class="controls">
                                        <input type="text" name="product_name" id="product_name">
                                    </div>
                                </div>

                                <div class="form-actions">
                                    <input type="submit" value="submit" class="btn btn-success">
                                </div>
                            </form>

I want to data like this in my product.blade.php

what data i want

thats why i use this code in product.blade.php

@foreach(App\Category::all() as $cat)
<option value="{{$cat->id}}" >{{ $cat->parent()->name ? $cat->parent()->name . ' -- ' : '' }}{{$cat->name}}</option>
@endforeach

but i facing error like this

ErrorException (E_ERROR)
Undefined property: Illuminate\Database\Eloquent\Relations\BelongsTo::$name (View: F:\laragon\www\flipcart\resources\views\admin\products\product.blade.php)
Previous exceptions
Undefined property: Illuminate\Database\Eloquent\Relations\BelongsTo::$name (0)

Answer 1

There are a number of things you may want to review in this code as there are several odd bits.

The error you are getting is caused by this code:

$cat->parent()->name

You are accessing a query builder instance when you call a relationship as a method rather than a property (ie ->parent() rather than ->parent ).

Try this instead:

$cat->parent->name

---

Your ternary statement should then be replaced with something like this:

$cat->parent ? $cat->parent->name . ' -- ' : ''