Laravel 8 数据过滤：基于数据库定义类别在 Blade 视图中筛选产品

// app/Models/Product.php
namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;

class Product extends Model
{
    use HasFactory;

    protected $fillable = ['name', 'category_id'];

    /**
     * Get the category that owns the product.
     */
    public function category()
    {
        return $this->belongsTo(Category::class);
    }
}

// app/Models/Category.php
namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;

class Category extends Model
{
    use HasFactory;

    protected $fillable = ['name'];

    /**
     * Get the products for the category.
     */
    public function products()
    {
        return $this->hasMany(Product::class);
    }
}

// 在你的控制器中
use App\Models\Category;

public function index($subdomain)
{
    // 从 categories 表中获取所有允许的类别名称
    // 假设 categories 表的 'name' 列存储了 'Book', 'Shirt' 等类别名称
    $allowedCategoryNames = Category::pluck('name')->toArray();

    // ... 后续筛选逻辑
}

// app/Http/Controllers/ProductController.php
<?php

namespace App\Http\Controllers;

use App\Models\Product;
use App\Models\Category;
use Illuminate\Http\Request;

class ProductController extends Controller
{
    public function index($subdomain)
    {
        // 1. 获取允许的类别名称列表
        $allowedCategoryNames = Category::pluck('name')->toArray();

        // 2. 使用 whereHas 筛选产品
        // 仅当 allowedCategoryNames 不为空时才应用筛选
        if (!empty($allowedCategoryNames)) {
            $products = Product::query()->whereHas('category', function ($query) use ($allowedCategoryNames) {
                $query->whereIn('name', $allowedCategoryNames);
            })->get();
        } else {
            // 如果没有允许的类别，则不返回任何产品或根据业务逻辑返回所有产品
            $products = collect(); // 返回空集合
            // 或者 $products = Product::all(); // 返回所有产品
        }

        return view('products.index', compact('products', 'allowedCategoryNames'));
    }
}

// app/Http/Controllers/ProductController.php
<?php

namespace App\Http\Controllers;

use App\Models\Product;
use App\Models\Category;
use Illuminate\Http\Request;

class ProductController extends Controller
{
    public function index($subdomain)
    {
        // 1. 获取允许的类别名称列表
        $allowedCategoryNames = Category::pluck('name')->toArray();

        // 2. 获取所有产品 (注意：这会加载所有产品到内存)
        // 为了避免 N+1 查询问题，建议使用 with('category') 预加载关系
        $allProducts = Product::with('category')->get();

        // 3. 使用 Collection 的 filter 方法筛选产品
        $products = $allProducts->filter(function (Product $product) use ($allowedCategoryNames) {
            // 确保产品有关联的类别，并且该类别的名称在允许列表中
            return $product->category && in_array($product->category->name, $allowedCategoryNames);
        });

        return view('products.index', compact('products', 'allowedCategoryNames'));
    }
}

<!-- resources/views/products/index.blade.php -->

<h1>产品列表</h1>

@if ($products->isEmpty())
    <p>没有找到符合条件的商品。</p>
@else
    <ul>
        @foreach ($products as $product)
            <li>
                <strong>{{ $product->name }}</strong>
                @if ($product->category)
                    <small>（类别: {{ $product->category->name }}）</small>
                @endif
            </li>
        @endforeach
    </ul>
@endif

<h2>允许的类别:</h2>
<ul>
    @foreach ($allowedCategoryNames as $categoryName)
        <li>{{ $categoryName }}</li>
    @endforeach
</ul>