How to select larger or max id from database flutter - flutter

Question

I am developing an application through which I need to display a larger id. It was previously added to the database through the following query:
Future<String> getLogin() async {
var response = await http.get(Uri.encodeFull("http://xxxxxxxxx/Noti.php"),);
setState(() {
var convertDataToJson = json.decode(response.body.toString());
data = convertDataToJson['result'];
if (data != null) {
User_ID =int.parse(data[0]['id']);
}
}
);
}
<?php
require_once 'connt.php';
$query="SELECT * FROM addcomment";
$result = mysqli_query($con,$query);
$array = array();
while ($row = mysqli_fetch_assoc($result))
{
$array[] = $row;
}
echo ($result) ?
json_encode(array("code" => 1, "result"=>$array)) :
json_encode(array("code" => 0, "message"=>"Data not found !"));
?>
Now like the example above works fine, but I need to take a higher id.
I created a php file like this:
<?php
require_once 'connt.php';
$query="SELECT MAX( id ) FROM addcomment";
$result = mysqli_query($con,$query);
$array = array();
while ($row = mysqli_fetch_assoc($result))
{
$array[] = $row;
}
echo ($result) ?
json_encode(array("code" => 1, "result"=>$array)) :
json_encode(array("code" => 0, "message"=>"Data not found !"));
?>
But I got the following problem:
E/flutter (29294): [ERROR:flutter/lib/ui/ui_dart_state.cc(166)] Unhandled Exception: Invalid argument(s): The source must not be null
E/flutter (29294): #0 int.parse (dart:core-patch/integers_patch.dart:51:25)
E/flutter (29294): #1 AddCommentsState.getLogin.<anonymous closure> (package:flutter_apptestqeuriy/Ready.dart:89:22)
E/flutter (29294): #2 State.setState (package:flutter/src/widgets/framework.dart:1240:30)
E/flutter (29294): #3 AddCommentsState.getLogin (package:flutter_apptestqeuriy/Ready.dart:85:5)
E/flutter (29294): <asynchronous suspension>
E/flutter (29294): #4 AddCommentsState.initState.<anonymous closure> (package:flutter_apptestqeuriy/Ready.dart:58:9)
E/flutter (29294): #5 interval.function (package:flutter_apptestqeuriy/Ready.dart:16:9)
E/flutter (29294): #6 _rootRun (dart:async/zone.dart:1182:47)
E/flutter (29294): #7 _CustomZone.run (dart:async/zone.dart:1093:19)
E/flutter (29294): #8 _CustomZone.runGuarded (dart:async/zone.dart:997:7)
E/flutter (29294): #9 _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:1037:23)
E/flutter (29294): #10 _rootRun (dart:async/zone.dart:1190:13)
E/flutter (29294): #11 _CustomZone.run (dart:async/zone.dart:1093:19)
E/flutter (29294): #12 _CustomZone.bindCallback.<anonymous closure> (dart:async/zone.dart:1021:23)
E/flutter (29294): #13 Timer._createTimer.<anonymous closure> (dart:async-patch/timer_patch.dart:18:15)
E/flutter (29294): #14 _Timer._runTimers (dart:isolate-patch/timer_impl.dart:397:19)
E/flutter (29294): #15 _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:428:5)
E/flutter (29294): #16 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:168:12)
E/flutter (29294):
I don't know what is the problem. But I need to display the highest id in the field. If someone knows the solution, please help me.

Answer 1

Replace;
$query="SELECT MAX( id ) AS max_id FROM addcomment";
And echo row[“max_id”]