drift/docs/lib/snippets/modular/schema_inspection.dart

import 'package:drift/drift.dart';

import 'drift/example.drift.dart';

// #docregion findById
extension FindById<Table extends HasResultSet, Row>
    on ResultSetImplementation<Table, Row> {
  Selectable<Row> findById(int id) {
    return select()
      ..where((row) {
        final idColumn = columnsByName['id'];

        if (idColumn == null) {
          throw ArgumentError.value(
              this, 'this', 'Must be a table with an id column');
        }

        if (idColumn.type != DriftSqlType.int) {
          throw ArgumentError('Column `id` is not an integer');
        }

        return idColumn.equals(id);
      });
  }
}
// #enddocregion findById

extension FindTodoEntryById on GeneratedDatabase {
  Todos get todos => Todos(this);

  // #docregion findTodoEntryById
  Selectable<Todo> findTodoEntryById(int id) {
    return select(todos)..where((row) => row.id.equals(id));
  }
  // #enddocregion findTodoEntryById
}