显示使用laravel 8从数据库中获取的下拉列表中的数据

Question

我必须在产品形式下拉显示类别值，给定的代码是从我的观点来看，错误是未定义的$类别。这是我在laravel的第一个代码，我不知道如何在其他文件中进行更改。foreach中使用哪个变量?或者我必须在ProductController中创建新功能?

<form action="/upload_product" method="post">
@csrf
<label>Choose Categories</label>
<select name="category_id" id="category" class="category">
<option disable selected>--select category--</option>
@foreach($categories as $item)
<option value="{{ $item->id }}">{{ $item->name}}</option>
@endforeach
</select>
<input type="text" name="name" placeholder="name">
<input type="number" name="sale_price" placeholder="sale_price">
</form>

模型Product.php

class Product extends Model
{
use HasFactory; 
protected $table = 'products';
public $timestamps = true;
public function category(){
return $this->belongsTo('AppModelsCategory');
} 

}模型Category.php

class Category extends Model
{
use HasFactory;
public $fillable = [ 'name' ];
protected $dates = [ 'deleted_at' ];
public $timestamps = true;
public function products (){
return $this->hasMany('AppModelsProduct');
}
}

ProductController.php

<?php
namespace AppHttpControllers; 
use AppModelsProduct;
use AppModelsCategory;
use IlluminateHttpRequest;
class ProductController extends Controller
{ 
public function index()
{
$products = Product::all(); 
return view('products/index', ['products'=>$products]);
}
public function view()
{
$products = Product::with('category')->get(); 
$categories = Category::with('products')->get();
return view ('product.view')-> with([
'products' => $products,
'categories' => $categories,
]);
}

Answer 1

你必须在

下面使用like

public function index(){
$products   = Product::all(); 
$categories = Category::with('products')->get();
return view('products.index', compact('products','categories'));
}

Answer 2

您的索引文件中没有$categories。基于index方法，您只发送产品:

public function index()
{
$products = Product::all(); 
return view('products/index', ['products'=>$products]);
}

所以也添加类别。

Answer 3

public function index()
{

$products = Product::get(); 
return view('products/index', ['products'=>$products]);
}

Answer 4

有三种方法

public function index(){
$products   = Product::all(); 
$categories = Category::with('products')->get();
return view('products.index', compact('products','categories'));
}
public function index(){
$products   = Product::all(); 
$categories = Category::with('products')->get();
return view('products.index')->with(['products'=>$products,'categories'=>$categories]));
}
public function index(){
$data['products']   = Product::all(); 
$data['categories'] = Category::with('products')->get();
return view('products.index',$data);
}