drift/moor/example/example.dart

import 'package:moor/moor.dart';

part 'example.g.dart';

// Define tables that can model a database of recipes.

@DataClassName('Category')
class Categories extends Table {
  IntColumn get id => integer().autoIncrement()();
  TextColumn get description => text().nullable()();
}

class Recipes extends Table {
  IntColumn get id => integer().autoIncrement()();
  TextColumn get title => text().withLength(max: 16)();
  TextColumn get instructions => text()();
  IntColumn get category => integer().nullable()();
}

class Ingredients extends Table {
  IntColumn get id => integer().autoIncrement()();
  TextColumn get name => text()();
  IntColumn get caloriesPer100g => integer().named('calories')();
}

class IngredientInRecipes extends Table {
  @override
  String get tableName => 'recipe_ingredients';

  // We can also specify custom primary keys
  @override
  Set<Column> get primaryKey => {recipe, ingredient};

  IntColumn get recipe => integer()();
  IntColumn get ingredient => integer()();

  IntColumn get amountInGrams => integer().named('amount')();
}

@UseMoor(
  tables: [Categories, Recipes, Ingredients, IngredientInRecipes],
  queries: {
    // query to load the total weight for each recipe by loading all ingredients
    // and taking the sum of their amountInGrams.
    'totalWeight': '''
      SELECT r.title, SUM(ir.amount) AS total_weight
        FROM recipes r
        INNER JOIN recipe_ingredients ir ON ir.recipe = r.id
      GROUP BY r.id
     '''
  },
)
class Database extends _$Database {
  Database(QueryExecutor e) : super(e);

  @override
  int get schemaVersion => 1;

  @override
  MigrationStrategy get migration {
    return MigrationStrategy(
      beforeOpen: (details) async {
        // populate data
        await into(categories)
            .insert(const CategoriesCompanion(description: Value('Sweets')));
      },
    );
  }
}