How to create self referential relationship in laravel? - laravel-4

Question

I am new to Laravel. I Just want to create a self referential model. For example, I want to create a product category in which the field parent_id as same as product category id. How is this possible?
Model Shown below
class Product_category extends Eloquent
{
protected $guarded = array();
public static $rules = array(
'name' => 'required',
'parent_id' => 'required'
);
function product_category()
{
return $this->belongsto('Product_category','parent_id');
}
}
It results Maximum function nesting level of '100' reached, aborting! Error

Answer 1

You can add a relation to the model and set the custom key for the relation field.
Update:
Try this construction
class Post extends Eloquent {
public function parent()
{
return $this->belongsTo('Post', 'parent_id');
}
public function children()
{
return $this->hasMany('Post', 'parent_id');
}
}
Old answer:
class Post extends Eloquent {
function posts(){
return $this->hasMany('Post', 'parent_id');
}
}

Answer 2

Your model is not at fault for producing the "maximum function nesting level of '100' reached" error. It's XDebug's configuration; increase your xdebug.max_nesting_level.
The following is from a 2015 post by #sitesense on laracasts.com:
This is not a bug in Laravel, Symfony or anything else. It only occurs when XDebug is installed.
It happens simply because 100 or more functions are called recursively. This is not a high figure as such and later versions of XDebug (>= 2.3.0) have raised this limit to 256. See here:
http://bugs.xdebug.org/bug_view_page.php?bug_id=00001100
EDIT: In fact the latest Homestead provisioning script already sets the limit to 250. See line 122 here:
https://github.com/laravel/settler/blob/master/scripts/provision.sh#L122
So the addition of xdebug.max_nesting_level = 250 to php.ini should do it.

Answer 3

I've added a little more to the code based on your comments trying to access the parent!
class Person extends \Eloquent {
protected $fillable = [];
var $mom, $kids;
function __construct() {
if($this->dependency_id<>0) {
$this->mother->with('mother');
}
}
public function children() {
$children = $this->hasMany('Person','dependency_id');
foreach($children as $child) {
$child->mom = $this;
}
return $children;
}
public function mother() {
$mother = $this->belongsTo('Person','dependency_id');
if(isset($mother->kids)) {
$mother->kids->merge($mother);
}
return $mother;
}
}
Then you can access the parent from the child with eager loading, see more here: http://neonos.net/laravel-eloquent-model-parentchild-relationship-with-itself/

Answer 4

you can refer self, using $this
class Post extends Eloquent {
function posts(){
return $this->hasMany($this, 'parent_id');
}
}

Answer 5

Take a look at my answer here.
The key is this code below in Model.php
public function children()
{
return $this->hasMany(Structure::class, 'parent_id')->with('children');
}