Eloquent Parent-Child relationship on same model

Question

I have a model CourseModule, and each of the items are related to the same model.

Database Structure:

Relation in Model:

    public function parent()     {         return $this->belongsTo('App\CourseModule','parent_id')->where('parent_id',0);     }      public function children()     {         return $this->hasMany('App\CourseModule','parent_id');     } 

I tried the following, but it returns only a single level of relation.

Tried:

CourseModule::with('children')->get(); 

I'm trying to create a json output like the following,

Expected Output:

[   {     "id": "1",     "parent_id": "0",     "course_id": "2",     "name": "Parent",     "description": "first parent",     "order_id": "1",     "created_at": "-0001-11-30 00:00:00",     "updated_at": "-0001-11-30 00:00:00",     "children": [       {         "id": "2",         "parent_id": "1",         "course_id": "2",         "name": "Child 1",         "description": "child of parent",         "order_id": "2",         "created_at": "-0001-11-30 00:00:00",         "updated_at": "-0001-11-30 00:00:00",         "children": [           {             "id": "3",             "parent_id": "2",             "course_id": "2",             "name": "Child2",             "description": "child of child1",             "order_id": "2",             "created_at": "-0001-11-30 00:00:00",             "updated_at": "-0001-11-30 00:00:00",             "children": [               {                 "id": "4",                 "parent_id": "3",                 "course_id": "2",                 "name": "Child 3",                 "description": "child of child 2",                 "order_id": "2",                 "created_at": "-0001-11-30 00:00:00",                 "updated_at": "-0001-11-30 00:00:00",                 "children": []               }             ]           }         ]       }     ]   } ] 

I don't understand how to get the inner child objects.

Answer 1

You should use with('children') in the children relation and with('parent') in the parent relations.

For your code to be recursive:

public function parent() {     return $this->belongsTo('App\CourseModule','parent_id')->where('parent_id',0)->with('parent'); }  public function children() {     return $this->hasMany('App\CourseModule','parent_id')->with('children'); } 

Note: Make sure your code has some or the other exit conditions otherwise it will end up in a never ending loop.