How to collect values from Json by key - php

Question

Thanks in prior for advising. I have the following JSON I retrieve from a REST Service.
"events": [
{
"id": 408,
"name": "My Test1",
"modulename": "test",
"instance": 0,
"timestart": 1470370500,
"timeduration": 864000,
},
{
"id": 418,
"name": "Quiz Open",
"modulename": "quiz",
"instance": 225,
"timestart": 1473737880,
"timeduration": 0,
},
{
"id": 423,
"name": "Quiz Close",
"modulename": "quiz",
"instance": 225,
"timestart": 1476665040,
"timeduration": 0,
},
{
"id": 409,
"name": "August event",
"modulename": "event",
"instance": 0,
"timestart": 1467295200,
"timeduration": 2474700,
}
]
I need to read the JSON and output in the following JSON format
"output": [
{
"name":
"Start":
"End":
}
]
My question comes in the point of the name as "Quiz" which is the "modulename" in the JSON input. The Quiz opens at a date (timestart) with modulename as "quiz" and "instance" - 225 as the unique identifier and ends at a different date ( timestart ) with the same instance id. The json contains 100s of events in one big array. My "End" in output json object is the "timestart" + "timeduration".
My Question is what is the effective algorithm to iterate if the module name is "quiz" get the instance and loop through the whole array to find the next occurence of the instance and add to the output json. Any pointers ?

Answer 1

At first make sure that your json is in right format if your json is like that:-
$str='{"events": [
{
"id": 408,
"name": "My Test1",
"modulename": "test",
"instance": 0,
"timestart": 1470370500,
"timeduration": 864000
},
{
"id": 418,
"name": "Quiz Open",
"modulename": "quiz",
"instance": 225,
"timestart": 1473737880,
"timeduration": 0
},
{
"id": 423,
"name": "Quiz Close",
"modulename": "quiz",
"instance": 225,
"timestart": 1476665040,
"timeduration": 0
},
{
"id": 409,
"name": "August event",
"modulename": "event",
"instance": 0,
"timestart": 1467295200,
"timeduration": 2474700
}
]}';
Then you can do this....`
$arr=json_decode($str,true);
$result=array();
$prevInstance=array();
foreach($arr['events'] as $key=>$val){
if($val['modulename']=='quiz' && array_key_exists($val['instance'], $prevInstance)){
$k= $prevInstance[$val['instance']];
$result['output'][$k]['End']=$val['timestart'];
}else{
$tmp['name']=$val['name'];
$tmp['Start']=$val['timestart'];
$tmp['End']=$val['timeduration'];
$result['output'][$val['id']]=$tmp;
}
$prevInstance[$val['instance']]=$val['id'];;
}
$data=array();
foreach ($result['output'] as $ret){
$data['output'][]=$ret;
}
echo "<pre>";
echo json_encode($data);

Answer 2

$array = json_decode($event,true); // first decode your retrieved array
$output = array();
foreach ($array as $key) { // then loop through it
if ($array[$key]['modulename'] == "quiz") { // only select if modulename is "quiz"
$obj = array("name" => $array[$key]['name'], "Start" => $array[$key]['timestart'], "END" => ($array[$key]['timestart'] + $array[$key]['timeend']));
array_push($output, $obj);
} else {
return;
}
}
return json_encode($output); // in last for output in JSON, encode the output array
//output: [{"name":"quiz","Start":123,"END":579},{"name":"quiz","Start":123,"END":579},{"name":"quiz","Start":123,"END":579}]