Laravel show array json - php

Question

I want to show data from database: for every id_grup has many lapangan(court)
$groups_resource = Groups::all();
$groups = [];
foreach($groups_resource as $group)
{
$g = new Groups();
$g->id_group = "Group_".$group['id_group'];
$g->name = $group['nama'];
$g->expanded = true;
$g->eventHeight = 25;
$g->children = array();
$groups[] = $g;
$lapangan_resource = Lapangan::with('groups')->orderBy('nama')->get();
foreach($lapangan_resource as $lapangan)
{
$l = new Lapangan();
$l->id_lapangan = $lapangan['id_lapangan'];
$l->name = $lapangan['nama_lapangan'];
$g->children[] = $l;
}
}
return json_encode($groups);
output for above code
[{"id_group":"Group_1","name":"Lapangan Badminton","expanded":true,"eventHeight":25,"children":[]},{"id_group":"Group_2","name":"Lapangan Tenis","expanded":true,"eventHeight":25,"children":[]}]
There is no value for children which might be like this.
[{"id":"group_1","name":"Indoor","expanded":true,"eventHeight":25,"children":[
{"id":"1","name":"Court 1"},
{"id":"2","name":"Court 2"},
{"id":"3","name":"Court 3"},
{"id":"4","name":"Court 4"}]},"id":"group_2","name":"Outdoor","expanded":true,"eventHeight":25,"children":[
{"id":"11","name":"Court 5"},
{"id":"12","name":"Court 6"},
{"id":"13","name":"Court 7"},
{"id":"14","name":"Court 8"}]}]

Answer 1

You are using wrong array braces. You shouldn't first initialize the children property of a group instead of that you can do it like this:
foreach($groups_resource as $group)
{
$g = new Groups();
$g->id_group = "Group_".$group['id_group'];
$g->name = $group['nama'];
$g->expanded = true;
$g->eventHeight = 25;
$l_arr = [];
$lapangan_resource = Lapangan::with('groups')->orderBy('nama')->get();
foreach($lapangan_resource as $lapangan)
{
$l = new Lapangan();
$l->id_lapangan = $lapangan['id_lapangan'];
$l->name = $lapangan['nama_lapangan'];
$l_arr[] = $l;
}
$g->children = $l_arr;
$groups[] = $g;
}
return json_encode($groups);
Hope this helps!