Laravel模型按关系计数

Question

I have an eCommerce site with a Product model and a ProductCategory model. I currently show products on the page from the Product model but would like to be able to get a list of all the categories with products in the current model and how many products are in each category. I can get the overall count but can't figure out how to get the list of categories being shown and how many results per category have been returned.

Product Model

• Product_ID
• Product_Name
• Product_Description
• Category_ID (Many-To-1: ProductCategory.Category_ID

ProductCategory Model

• Category_ID
• Category_Name

Currently, I access the results in the blade using...

@foreach($products->chunk(3) as $row)
    <div class="item-row">
        @foreach($row as $product)
            <div class="item item-thumbnail" style="height: 250px;">
                <a href="product_detail.html" class="item-image">
                    @if(empty($product->Images{0}->original_image))
                        <img style="width: 100px; height: 100px;" 
                            src="https://example.com/100x100/d3d3d3/fff.gif&text=No+Image" 
                            alt="" />
                    @else
                        <img style="width: 100px; height: 100px;" 
                            src="https://cdn.example.com.au/products/{{$product->id}}/{{$product->Images{0}->original_image}}" 
                            alt="" />
                    @endif
                </a>

                <div class="item-info">
                    <h4 class="item-title">
                        <a href="/store/{{$category->alias}}/{{$product->alias}}">
                            {{$product->product_name}}
                        </a>
                    </h4>
                    <p class="item-desc">&nbsp;</p>
                    @if(empty($product->special_price))
                        <div class="item-price">
                            ${{$product->normal_price}}
                        </div>
                    @else
                        <div class="item-price">
                            ${{$product->special_price}}
                        </div>
                        <div class="item-discount-price">
                            ${{$product->normal_price}}
                        </div>
                    @endif
                </div>
            </div>
        @endforeach 
    </div>
@endforeach

And would like to be able to generate a list of all the categories with products displayed as...

@foreach($products->categories as $category)
    <li>
        {{$category->category_name}} ({{$category->count}})
    </li>
@endforeach

All from within the same model.

Additional

If it helps clarify I don't want the model to change drastically in that I still want to be able to access the products in the model from the blade template as is currently done but would like to also be able to pull a list of categories such as the below example...

| Product_ID | Product_Name | Category_ID |
| ---------- | ------------ | ----------- |
| 1          | Product 1    | 1           |
| 2          | Product 2    | 1           |
| 3          | Product 3    | 2           |


| Category ID | Category Name |
| ----------- | ------------- |
| 1           | Category 1    |
| 2           | Category 2    |

And wind up with the following table on my page to show the product categories being shown in the results...

| Category Name | # Products |
| ------------- | ---------- |
| Category 1    | 2          |
| Category 2    | 1          |

Answer 1

It would be super helpful if you provided the code where you query the products and categories.

But here's essentially what you need to do. You need to make use of ->withCount(..):

$products = Product::with([
    'categories' => function ($query) {
        // Adds count of category-related products
        $query->withCount('products as count');
    },
])->get();

And then this would work in your view:

@foreach($products as $product)
    @foreach($product->categories as $category)
        <li>{{$category->category_name}} ({{$category->count}})</li>
    @endforeach
@endforeach