Question 243008 in Flutter Question posted in
The official Flutter documentation can be found here.

Flutter : Recover sqlite data in combobox

I want to recover data from my table and put them in my dropdown.
I get an error message : _TypeError (type ‘Future’ is not a subtype of type ‘List’)
Thank you for your help

readData(table) async {
  var connection = await db;
  return await connection.query('SELECT nom_A FROM tab_A');
}


class DropdownMenuA extends StatefulWidget {
  const DropdownMenuA({super.key});
//Modif

  @override
  State<DropdownMenuA> createState() => _DropdownMenuAState();
}

class _DropdownMenuAState extends State<DropdownMenuA> {
  //String dropdownValueA = list1.first;
  List<String> listA = readData(Tab_A);

  @override
  Widget build(BuildContext context) {
    return DropdownMenu<String>(
      initialSelection: listA.first,
      onSelected: (String? value) {
        // This is called when the user selects an item.
        setState(() {
          //dropdownValueA = value!;
        });
      },
      dropdownMenuEntries: listA.map<DropdownMenuEntry<String>>((String value) {
        return DropdownMenuEntry<String>(value: value, label: value);
      }).toList(),
    );
  }
}
Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    I think I have a problem with my request, your code is good :

    readData(table) async { var connection = await db; return await connection.query('SELECT * FROM tab_A '); //return await connection.query('tab_A'); }

    I have this error : Exception has occurred. SqfliteFfiException (SqfliteFfiException(sqlite_error: 1, , SqliteException(1): while preparing statement, near "SELECT": syntax error, SQL logic error (code 1) Causing statement: SELECT * FROM SELECT * FROM tab_A }) DatabaseException(SqliteException(1): while preparing statement, near "SELECT": syntax error, SQL logic error (code 1) Causing statement: SELECT * FROM SELECT * FROM tab_A ) sql 'SELECT * FROM SELECT * FROM tab_A ' {details: {database: {path: E:ProjetsFluttertablesabc.dart_toolsqflite_common_ffidatabases
    db_tablesabc, id: 1, readOnly: false, singleInstance: true}}})

    If I put this request :

    readData(table) async { var connection = await db; //return await connection.query('SELECT * FROM tab_A '); return await connection.query('tab_A'); }

    I have this error : Exception has occurred. _TypeError (type 'QueryResultSet' is not a subtype of type 'List')


  2. 0

    Put await keyword for the Future call. Like:

    List<String> listA = await readData(Tab_A);

    In order to use await keyword you must also use the async keyword as well like:

    Future<void> fetchData() async {
    List<String> data = await readData(Tab_A);
    setState(() {
      listA = data;
    });
  }

    And call this fetchData() function inside initState() function like:

     @override
  void initState() {
    super.initState();
    fetchData();
  }

    Final code looks like:

    class _DropdownMenuAState extends State<DropdownMenuA> {
  List<String> listA = [];

  @override
  void initState() {
    super.initState();
    fetchData();
  }

  Future<void> fetchData() async {
    List<String> data = await readData(Tab_A);
    setState(() {
      listA = data;
    });
  }

  @override
  Widget build(BuildContext context) {
    return DropdownMenu<String>(
      initialSelection: listA.isNotEmpty ? listA.first : null,
      onSelected: (String? value) {
      
        setState(() {
  
        });
      },
      dropdownMenuEntries: listA.map<DropdownMenuEntry<String>>((String value) {
        return DropdownMenuEntry<String>(value: value, label: value);
      }).toList(),
    );
  }
}

    Kindly, let me know if it works.

    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search