Laravel的动态关系加载

Laravel的负载方法提供了一种灵活的方法，可以在现有模型或集合上急切地负载关系。这种方法可以防止n 1查询问题，同时允许您仅在必要时加载关系。

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<!-- Syntax highlighted by torchlight.dev -->$post->loadMissing(['comments', 'author']);
// With constraints
$post->loadMissing(['comments' => function($query) {
    $query->latest()->take(5);
}]);

当具有可选的不同部分需要不同的关系数据的可选或仪表板时，此功能尤其有价值。

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<!-- Syntax highlighted by torchlight.dev --><?php

namespace App\Http\Controllers;

use App\Models\Dashboard;
use Illuminate\Http\Request;

class DashboardController extends Controller
{
    public function show(Request $request, Dashboard $dashboard)
    {
        // Load base relationships
        $dashboard->loadMissing([
            'widgets',
            'owner',
        ]);

        // Conditionally load additional data
        if ($request->section === 'analytics') {
            $dashboard->loadMissing([
                'widgets.viewHistory' => function($query) {
                    $query->whereBetween('viewed_at', [
                        now()->subDays(30),
                        now()
                    ]);
                },
                'widgets.interactions'
            ]);
        }

        if ($request->section === 'sharing') {
            $dashboard->loadMissing([
                'sharedUsers',
                'shareLinks' => function($query) {
                    $query->where('expires_at', '>', now());
                }
            ]);
        }
        return $dashboard;
    }
}

以下是仪表板数据加载程序的示例：

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<!-- Syntax highlighted by torchlight.dev -->// GET /dashboard/1?section=analytics
{
    "id": 1,
    "name": "Sales Overview",
    "widgets": [
        {
            "id": 1,
            "type": "chart",
            "viewHistory": [
                {
                    "viewed_at": "2024-02-01T10:30:00Z",
                    "views": 150
                }
            ],
            "interactions": [
                {
                    "type": "filter_change",
                    "timestamp": "2024-02-01T11:20:00Z"
                }
            ]
        }
    ]
}

>加载提供了一种管理关系加载，优化数据库查询的有效方法，同时保持代码灵活性。

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