显示主要类别下的子类别和项目数

Question

I'm new to Laravel and trying to learn a bit while I build "real world" project.

My project is classified site. Currently I'm on step where I should show all categories, sub-categories and number of items under each sub-category.

In the database I story all categories (main and sub) in table called categories. There is column called parent_id which is the ID of the parent category (if is sub-category).

In the model Category.php I have

public function item()
{
    return $this->hasMany('Item','category_id');
}

public function children()
{
    return $this->hasMany('App\Category', 'parent_id');
}

public function getCategories()
{
    $categoires = Category::where('parent_id',0)->get();
    $categoires = $this->addRelation($categoires);
    return $categoires;
}

public function selectChild( $id )
{
    $categoires = Category::where('parent_id',$id)->get();
    $categoires = $this->addRelation($categoires);
    return $categoires;
}

public function addRelation( $categoires )
{

  $categoires->map(function( $item, $key)
  {             
        $sub = $this->selectChild($item->id);
        $item->itemCount = $this->getItemCount($item->id , $item->parent_id );
        return $item = array_add($item, 'subCategory', $sub);
    });
    return $categoires;
}

public function getItemCount( $category_id, $parent_id )
{

    if( $parent_id == 0)
    { // for root-caregory

         $ids = Category::select('id')->where('parent_id', $category_id)->get();
         $array = array();

         foreach ($ids as $id)
         {
            $array[] =  $id->id;
         }

         return Item::whereIn('category_id', $array )->count();
    }
    else
    {
        return Item::where('category_id', $category_id)->count();
    }
}

In my controller

public function index()
{
    $Category = new Category;
    $allCategories = $Category->getCategories();
    return view('frontend.home', compact('allCategories'));
}

In the view this is how I showed the parent categories

@foreach($allCategories as $cats)
     <li><a href="#">{{ $cats->title }}</a>/li>
@endforeach

What I've tried for the sub-categories is to add one if inside the foreach

@foreach($allCategories as $cats)
     <li><a href="#">{{ $cats->title }}</a>
          <ul class="sub-category">
              @if ($cats->children())
                <li><a href="#"> {{ $cats->children->title }} </a></li>
              @endif
          </ul>
     </li>
@endforeach

The error is

Undefined property: Illuminate\Database\Eloquent\Collection::$title

When I {{ dd($allCategories) }} I see that they are in the array.

Answer 1

Your children relation will return a collection and not a single model, because of this you have to loop through the children aswell:

@foreach($allCategories as $cats)
    <li><a href="#">{{ $cats->title }}</a>
        <ul class="sub-category">
            @if($cats->children)
                @foreach($cats->children as $child)
                    <li><a href="#"> {{ $child->title }} </a></li>
                @endforeach
            @endif
        </ul>
    </li>
@endforeach