pulling data with php json, but getting an error in Flutter application-CodePudding

I'm developing a country-city-like system. I'm pulling the data with json via phpmyadmin. but even if the system is working, it crashes from time to time.

Padding(
  padding: const EdgeInsets.only(left: 20, right: 20),
  child: DropdownButton(
  dropdownColor: Colors.white,
  value: selectedfakId,

  hint: Text("Fakülte Seçin"),
  items: datafak?.map((faklist) {
                        
  return new DropdownMenuItem(
     child: Text(faklist["name"]),
     value: faklist["fakulte_id"],
  );
}).toList() ??[],
onChanged: (value) {
   setState(() {
      selectedfakId = value as String?;
});
},



Future fakliste() async {
var url = "https://www.forumuni.com/forumunimob/unilist.php?send=faklist";

// ignore: unused_local_variable
var response = await http.post(Uri.parse(url),
    body: {"uniid": selectedId}, headers: {"Accept": "application/json"});

var jsonbody = response.body;
var jsondata = json.decode(jsonbody);

setState(() {
  datafak = jsondata;
});

// ignore: avoid_print
print(jsondata);
return "success";
}

PHP code:

$list = array();

    $uniid = $_POST["uniid"];

    $fak = $conn->query("SELECT * FROM table WHERE id = '$uniid' ORDER BY name");

    while($faklist = $fak->fetch(PDO::FETCH_ASSOC))
    {
        $list[] = $faklist;
    }

    if($uniid != null)
    {
        echo json_encode($list);
    }
    else
    {
        echo json_encode("a");
    }

Error

CodePudding user response：

You are getting this error because faklist["fakulte_id"] of every item is not unique, two or more values of fakulate_id is same. Where as value in DropDownButton needs unique value for every item.

Make sure fakulte_id is unique, else you need to change the value to something which has unique value for every item in DropDownButton.