Laravel – 获取关系计数

Question

I'm new to laravel. I used laravel 5.4

I have this problem and I dont know where to start.

I want to count all assets in Storage where all of its category is Electronic.

Heres my Table:

Assets

 -- 
 id
 asset_name
 asset_type_id (fk)

AssetType

 --
 id
 asset_type
 category_id (fk)

Category

 --
 id
 category

Heres my defined model:

Asset Model

public function assetType(){
     return $this->belongsTo(AssetType::class);
}
public function category(){
     return $this->belongsTo(Category::class);
}

AssetType Model

public function category(){
     return $this->belongsTo(Category::class);
 }

public function assets(){
     return $this->hasMany(Asset::class);
}

Category Model

public function types(){
     return $this->hasMany(AssetType::class);
}

Controller:

AssetController

public function index()
    {
        $result = Asset::all();

        return view('asset.index', compact('result'));
    }

View:

index.blade

@foreach($result as $asset)
<tr>

    <td>{{ $asset->asset_name }}</td>
    <td>{{ $asset->assetType->asset_type}}</td>
    <td>{{ $asset->assetType->category->category}}</td>


</tr>
@endforeach

Sample Result:

Asset: DELL
Asset Type: Laptop
Category: Electronic

With that I can view all assets.

I'm trying to get the count of all assets whose category is Electronic in controller and pass it to view. Please enlighten me I'm lost.

Answer 1

You may use a Has Many Through relationship on your Category like so.

Category Model

public function assets()
{
    return $this->hasManyThrough(Asset::class, AssetType::class);
}

With this you can easily reach Asset from Category . Now count your assets in your controller:

Category::where('category', 'Electronic')->withCount('assets')->get();