php print json output data in group - php

Question

I have this output results from database:
Array
(
[0] => stdClass Object
(
[name] => attr one
[attribute_id] => 1
[attribute_group] => group one
[attribute_group_id] => 1
)
[1] => stdClass Object
(
[name] => attr two
[attribute_id] => 2
[attribute_group] => group one
[attribute_group_id] => 1
)
[2] => stdClass Object
(
[name] => attr three
[attribute_id] => 3
[attribute_group] => group one
[attribute_group_id] => 1
)
[3] => stdClass Object
(
[name] => attr four
[attribute_id] => 4
[attribute_group] => group two
[attribute_group_id] => 2
)
)
now for json ouput:
foreach ($results as $result) {
$json[] = array(
'id' => $result->attribute_group_id,
'text' => $result->attribute_group,
'children' => [array(
'id' => $result->attribute_id,
'text' => $result->name,
)]
);
}
return json_encode($json);
output is:
[
{
"id":"1",
"text":"group one",
"children":[
{
"id":"1",
"text":"attr one"
}
]
},
{
"id":"1",
"text":"group one",
"children":[
{
"id":"2",
"text":"attr two"
}
]
},
{
"id":"1",
"text":"group one",
"children":[
{
"id":"3",
"text":"attr three"
}
]
},
{
"id":"2",
"text":"group two",
"children":[
{
"id":"4",
"text":"attr four"
}
]
}
]
But In Action I need to output grouped by attribute_group and listed in children like this:
[
{
"id":"1",
"text":"group one",
"children":[
{
"id":"1",
"text":"attr one"
},
"id":"2",
"text":"attr two"
},
{
"id":"3",
"text":"attr three"
}
]
},
{
"id":"2",
"text":"group two",
"children":[
{
"id":"4",
"text":"attr four"
}
]
}
]
how do can i create this json output?!

Answer 1

Instead of creating an array $json with an element for each attribute, you should gather each attribute directly by attribute_group_id.
In order to do that, the idea is to use the attribute_group_id as the key of your $json array ($json[$result->attribute_group_id]). If an entry already exists for $json[$result->attribute_group_id]['children'] then you just have to had the current children to this item. If not, you create the entry for the current attribute group ID with his information (id,text,children).
Finally you can return the $json without the key that we used for grouping the attributes using array_values (returns the values of an array without keys).
foreach ($results as $result) {
if(isset($json[$result->attribute_group_id]['children'])){
$json[$result->attribute_group_id]['children'][] = array(
'id' => $result->attribute_id,
'text' => $result->name,
);
}
else {
$json[$result->attribute_group_id] = array(
'id' => $result->attribute_group_id,
'text' => $result->attribute_group,
'children' => [array(
'id' => $result->attribute_id,
'text' => $result->name,
)]
);
}
}
return json_encode(array_values($json));
Result :
[
{
"id": "1",
"text": "group one",
"children": [
{
"id": "1",
"text": "attr one"
},
{
"id": "2",
"text": "attr two"
},
{
"id": "3",
"text": "attr three"
}
]
},
{
"id": "2",
"text": "group two",
"children": [
{
"id": "4",
"text": "attr four"
}
]
}
]