Access method to a SQL model class through the parent table - flutter

Question

I have a DB with two tables, each table has his own class with toMap and fromMap method. Each table has a provider and SQLhelper class with the CRUD. My question is how can I access to the table 2 when I only have the context of the table 1 (parent table). The idea is to access to the model class secondTable().
The secondtable.id is the foreign key which references firsttable.id
In my second table sql operations I'm trying this way:
Future<List<Map<String, dynamic>>> getData(int firstTableId) async {
final db = SQLite.db;
List<Map<String, dynamic>> results = await db.rawQuery('''
SELECT *
FROM secondtable
INNER JOIN firsttable ON secondtable.id = firsttable.id
WHERE id = ?
''', [firstTableId]);
return results;
After that I have a provider:
Future<SecondTable?> getData(int firstTableId) async {
final results = await _databaseHelper.getData(firstTableId);
if (results.isNotEmpty) {
Map<String, dynamic> row = results.first;
SecondTable secondTable = SecondTable.fromMap(row);
return secondTable;
} else {
return null;
}
}
And in the page that I need the information I call the provider like that:
#override
void initState() {
super.initState();
_seconTableDataProvider =
Provider.of<SecondTableDataProvider>(context, listen: false);
loadSecondTable();
}
FirstTable _firstTable = FirstTable();
SecondTable? _secondTable = SecondTable();
Future<void> loadSecondTable() async {
_secondTable = await _seconTableDataProvider.getData(_firstTable.id!);
}
I have always a cast error, because return me null. If I hardcode an id like:
_seconTableDataProvider.getData(1);
The problem is DatabaseException(ambiguous column name: id
But if I create a new variable as a foreign key. It doesn't take the value ok the firstTable column referenced and its null again.
I don't know how to act now.

Answer 1

There is a problem in the SQL syntax. The correct way to do it is:
List<Map<String, dynamic>> results = await db.rawQuery('''
SELECT secondtable.*
FROM secondtable
INNER JOIN firsttable ON secondtable.firstTableId = firsttable.id
WHERE firsttable.id = ?
''', [firstTableId]);
After that you have to make sure to initialize the _firstTable.
#override
void initState() {
super.initState();
_secondTableDataProvider =
Provider.of<SecondTableDataProvider>(context, listen: false);
}
#override
void didChangeDependencies() {
super.didChangeDependencies();
_firstTable = ModalRoute.of(context)!.settings.arguments as FirstTable;
loadSecondTable();
}
And finally you need to take care with the async call to the loadSecondTable function, due the time it needs to acces the data. So use Fututrebuilder or other options.