When working with Laravel and its Eloquent ORM, sorting records based on related table columns can sometimes be challenging, especially when dealing with a hasMany relationship. This article aims to provide a solution for sorting records efficiently in such scenarios.
Problem
Consider a situation where you have two models, `Asset` and `AssetHistory`, with a hasMany relationship between them. You want to fetch assets along with their latest asset history record and sort them based on a column in the `AssetHistory` table, such as `created_at`.
Solution
Step 1: Define Relationships
As a first step you need to ensure that you have defined the relationships correctly in your models.
```php
// Asset.php
namespace App\Models;
use Illuminate\Database\Eloquent\Model;
class Asset extends Model
{
/**
* Get the asset histories for the asset.
*/
public function assetHistories()
{
return $this->hasMany(AssetHistory::class);
}
}
“`
/** * Insert your code here */
Step 2: Fetch Assets with Latest Asset History and Sort
Now, let’s write the code to fetch assets along with their latest asset history records and sort them based on the `created_at` column in the `AssetHistory` table.
```php
use App\Models\Asset;
use Illuminate\Support\Facades\DB;
// Fetch assets with latest asset history
$assets = Asset::with(['assetHistories' => function ($query) {
// Subquery to get the latest asset history for each asset
$query->select(DB::raw('MAX(id) as max_id'))->groupBy('asset_id');
}])
->leftJoin('asset_histories', function ($join) {
// Join with the latest asset history records
$join->on('asset_histories.asset_id', '=', 'assets.id')
->on('asset_histories.id', '=', DB::raw('(SELECT max_id FROM asset_histories)'));
})
->orderBy('asset_histories.created_at', 'desc') // Sort by created_at in asset_histories
->get();
// Now $assets contains assets with their latest asset history records sorted by created_at
```
Explanation
- We use the `with` method to eager load the `assetHistories` relationship with a callback function.
- Within the callback function, we select the maximum `id` for each `asset_id` in the `asset_histories` table using a subquery.
- Then, we perform a left join with `asset_histories` where we match the `asset_id` and the `id` obtained from the subquery, ensuring we get the latest asset history record for each asset.
- Finally, we order the results based on the `created_at` column of the latest asset history record.
Conclusion
By following the steps outlined above, Laravel development agencies can efficiently fetch assets with their latest asset history records. Laravel developers can sort them based on related table columns even when dealing with a has many relationships in Laravel. This approach ensures accuracy and performance in sorting records based on related data, making it a valuable technique for Laravel development projects.