Extra watch tables in select with join

[davidmartos96]

Hello!
I've updated to moor 4.x and now I'm getting a warning for creating a wrapper for JoinedSelectStatement, which I implemented a while ago. The warning is for subtyping a sealed class.

The use case is using the Dart query API but I need to specify some extra tables as "watchable" so that they work with stream queries. Those need to be specified explicitly because I use them in a custom expression as shown below.

Does it make sense to include an extra argument to the moor API, or is there another way to do it?

Here is the example:

    final extraExpr = CustomExpression<String>("""
(
  SELECT something
  FROM otherTable 
)""");

   final results = withCustomWatch(
    select(table),
    extraWatchTables: [otherTable],
    joins: [
      someJoins
    ],
  )..addColumns([
      extraExpr,
    ]);

My wrapper implementation:

import 'package:moor/moor.dart';

class ExtraWatchTableSelectable<FirstT extends Table, FirstD extends DataClass>
    extends JoinedSelectStatement<FirstT, FirstD> {
  final List<TableInfo> extraWatchTables;

  ExtraWatchTableSelectable(
    DatabaseConnectionUser database,
    TableInfo<FirstT, FirstD> table,
    List<Join<Table, DataClass>> joins,
    this.extraWatchTables,
  ) : super(database, table, joins);

  @override
  Set<TableInfo> get watchedTables =>
      super.watchedTables..addAll(extraWatchTables);
}

ExtraWatchTableSelectable<T, D>
    withCustomWatch<T extends Table, D extends DataClass>(
  SimpleSelectStatement<T, D> select, {
  List<TableInfo> extraWatchTables, 
  List<Join<Table, DataClass>> joins = const [],
}) {
  final statement = ExtraWatchTableSelectable(
    // ignore:invalid_use_of_protected_member
    select.database,
    select.table,
    joins,
    extraWatchTables,
  );

  return statement;
}

[simolus3]

In moor 4.1, there's subqueryExpression but I've just realized that doesn't properly add extra tables either 🤦

I think the best solution (for moor) is to add a method to report watched tables to the GenerationContext. I've opened #1095 to track that. I think we could add a parameter to CustomExpression to describe added tables then.

[davidmartos96]

Oh yes, the subqueryExpression would work, but knowing that it doesn't propertly handle the watched tables I'll stick with the wrapper for now. I just need to ignore the warning 👀
Thanks @simolus3 !