如何在 Laravel 中创建类别的嵌套列表

发布于05月16日

如何在Laravel中创建嵌套的类别列表？

我想创造这样的东西:

--- Php
------拉维尔
--------- Version
------------ V 5.7
--- Python
------德扬戈
--- Ruby
.

The fields of my categories table are:

id | name | parent_id

If I have to add another column like depth or something, please tell me.

我正在使用以下代码，但我认为这不是最好的解决方案.此外，我不能把这个功能放在我的观点上.

function rec($id)
{
     $model = Category::find($id);
     foreach ($model->children as $chield) rec($chield->id);
     return $model->all();
}

function main () {
    $models = Category::whereNull('parent_id')->get();
    foreach ($models as $parent) return rec($parent->id);
}

推荐答案

You can make a self-referential model:

class Category extends Model {

    public function parent()
    {
        return $this->belongsTo('Category', 'parent_id');
    }

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

and make a recursive relation:

// recursive, loads all descendants
public function childrenRecursive()
{
   return $this->children()->with('childrenRecursive');
}

and to get parents with all their children:

$categories = Category::with('childrenRecursive')->whereNull('parent_id')->get();

Lastly you need to just iterate through the children until children is null. There can definitely be some performance issues with this if you are not careful. If this is a fairly small dataset that you plan to remain that way it shouldn't be an issue. If this is going to be an ever growing list it might make sense to have a root_parent_id or something to query off of and assemble the tree manually.