Laravel 将所有父类别显示为特定子类别的树

Question

I'm trying to get categories tree of a sub-category

Let's say i have a sub-category called Accessories

this sub-category have parents of Electronics > Laptops

So it is Electronics > Laptops > Accessories

Table :

-----------------------------------------
| id    | parent_id     | name          |
|----   |-----------    |-------------  |
| 1     | 0             | Electronics   |
| 2     | 1             | Laptops       |
| 3     | 2             | Accessories   |
-----------------------------------------

I can get the root category of a sub-category like :

function getTopParent($category) {
    if($category->parent_id === null) {
        return $category->name;
    }

    return getTopParent(App\Category::find($category->parent_id));

    // Will return Electronics

}

Also i know how to display categories like tree, see here

function printCategoryName($categories, $parentName = '') {
    foreach ($categories as $category) {
        $name = $parentName ? implode(' > ', [$parentName, $category->name]) : $category->name;
        echo sprintf('%s%s', $name, PHP_EOL);

        if (count($category->children) > 0) {
            printCategoryName($category->children, $name);
        }
    }
}

printCategoryName($categories);

What i need is give a category like Accessories and get tree and get category tree for this sub-category :

Electronics > Laptops > Accessories .

How can i achieve this?

Answer 1

This is how i got it working :

function getParentsTree($category, $name)
{
    if ($category->parent_id == null)
    {
        return $name;
    }

    $parent = Category::find($category->parent_id);
    $name = $parent->name . ' > ' . $name;

    return getParentsTree($parent, $name);
}   

$cat = Category::find(1);
echo getParentsTree($cat, $cat->name);

Output : Electronics > Laptops > Accessories

Answer 2

您应该阅读嵌套集模型

Answer 3

This is a Common problem solved by the composite design pattern

Compose objects into tree structures to represent whole-part hierarchies. Composite lets clients treat individual objects and compositions of objects uniformly. Recursive composition "Directories contain entries, each of which could be a directory." 1-to-many "has a" up the "is a" hierarchy

Source

You can see an example of composite design pattern implementation with php here

Answer 4

I'm using this structure

your enter category model App\\Category.php

class Categories extends Model
{
    public function parent()
    {
       return $this->hasOne('App\Category', 'parent_id','id');
    }
    public function childiren()
    {
       return $this->hasMany('App\Category', 'id','parent_id');
    }
}

your controller ExampleController.php

public function example()
{
    $data = Category::all();
    return view('index', compact('data'));
}

your blade index.blade.php

<select>
    @foreach($data as $categories)
        <optgroup label="{{ $categories->name }}">
            @foreach($categories->children as $category)
                <option value="{{ $category->id }}">{{ $category->name }}</option>
            @endforeach
        </optgroup>
    @endforeach
</select>

also you use jquery select 2

Answer 5

    protected function getCategoriesTree()
    {
        $categories = Category::where('parent_id',0)->get();

        if($categories->count())
        {
            foreach ($categories as $category) 
            {
                $categories_tree[$category->id] = $this->getChildCategories($category);
            }
        }

        return response()->json(['categories' => $categories_tree]);
    }

    private function getChildCategories($category)
    {
        $sub_categories = [];

        $childs = Category::where('parent_id', $category->id)->get();

        $sub_categories = $category;

        $sub_categories['sub_categories'] = [];

        if($childs->count())
        {
            $sub_categories['sub_categories'] = $childs;
        }

        return $sub_categories;
    }