drift/sally

Sally

Sally is an easy to use and safe way to persist data for Flutter apps. It features a fluent Dart DSL to describe tables and will generate matching database code that can be used to easily read and store your app's data.

Note: This library is in development and not yet available for general use on pub.

Using this library

Adding the dependency

First, let's add sally to your prooject's pubspec.yaml:

dependencies:
  sally:
    git:
      url: 
      path: sally/

dev_dependencies:
  sally_generator:
    git:
      url:
      path: sally_generator/
  build_runner:

We're going to use the sally library to specify tables and write data. The sally_generator library will take care of generating the necessary code so the library knows how your table structure looks like.

Declaring tables

You can use the DSL included with this library to specify your libraries with simple dart code:

import 'package:sally/sally.dart';

// assuming that your file is called filename.dart. This will give an error at first,
// but it's needed for sally to know about the generated code
part 'filename.g.dart'; 

class Todos extends Table {
  IntColumn get id => integer().autoIncrement()();
  TextColumn get name => text().withLength(min: 6, max: 10)();
  TextColumn get content => text().named('body')();
  IntColumn get category => integer()();
}

class Categories extends Table {
  @override
  String get tableName => 'todo_categories';
  
  IntColumn get id => integer().autoIncrement()();
  TextColumn get description => text()();
}

@UseSally(tables: [Todos, Categories])
class MyDatabase {
  
}

⚠️ Warning: Even though it might look like it, the content of a Table class does not support full Dart code. It can only be used to declare the table name, it's primary keys and columns. The code inside of a table class will never be executed. Instead, the generator will take a look at your table classes to figure out how their structure looks like. This won't work if the body of your tables is not constant. This should not be problem, but please be aware of this.

Generating the code

Sally integrates with the dart build system, so you can generate all the code needed with flutter packages pub run build_runner build. If you want to continously rebuild the code whever you change your code, run flutter packages pub run build_runner watch instead. After running either command once, sally generator will have created a class for your database and data classes for your entities. To use it, change the MyDatabase class as follows:

@UseSally(tables: [Todos, Categories])
class MyDatabase extends _$MyDatabase {
  @override
  int get schemaVersion => 1;
  @override
  MigrationStrategy get migration => MigrationStrategy();
}

You can ignore these two getters there at the moment, the important part is that you can now run your queries with fluent Dart code:

class MyDatabase extends _$MyDatabase {
  // .. the getters that have been defined above still need to be here

  Future<List<Todo>> get allTodoEntries => select(todos).get();

  Future<void> deleteCategory(Category toDelete) async {
    await (delete(todos)..where((entry) => entry.category.equalsVal(category.id))).go();
    await (delete(categories)..where((cat) => cat.id.equalsVal(toDelete.id))).go();
  }
}

TODO-List

If you have suggestions for new features or any other questions, feel free to create an issue.

Before this library can be released

• Custom primary keys
• Stabilize all end-user APIs and document them extensively
• Support default values and expressions, auto-increment

Definitely planned for the future

• Allow using DAOs instead of having to put everything in the main database class.
• Support more Datatypes: We should at least support DateTime and Uint8List, supporting floating / fixed point numbers as well would be awesome
• Nullable / non-nullable datatypes
  • DSL API
  • Support in generator
  • Use in queries (IS NOT NULL)
  • Setting fields to null during updates
• Verify constraints (text length, nullability, etc.) before inserting or deleting data.
• Support Dart VM apps
• References
• Table joins

Interesting stuff that would be nice to have

• GROUP BY grouping functions
• Support for different database engines
  • Support webapps via AlaSQL or a different engine