Getting started

Simple guide to get a moor project up and running

Note: If you prefer a tutorial video, Reso Coder has made a detailed video explaining how to get started. You can watch it here.

Adding the dependency

First, lets add moor to your project's pubspec.yaml. At the moment, the current version of moor is Moor version and the latest version of moor_generator is Generator version

  moor: # use the latest version
  sqlite3_flutter_libs: # Also use the latest version.

  moor_generator: # use the latest version

If you're wondering why so many packages are necessary, here's a quick overview over what each package does:

  • moor: This is the core package defining most apis
  • sqlite3_flutter_libs: Ships the latest sqlite3 version with your Android or iOS app.
  • path_provider and path: Used to find a suitable location to store the database. Maintained by the Flutter and Dart team
  • moor_generator: Generates query code based on your tables
  • build_runner: Common tool for code-generation, maintained by the Dart team

Some versions of the Flutter tool create a broken settings.gradle on Android, which can cause problems with moor_ffi. If you get a "Failed to load dynamic library" exception, see this comment.

Declaring tables

Using moor, you can model the structure of your tables with simple dart code:

import 'package:moor/moor.dart';

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

// this will generate a table called "todos" for us. The rows of that table will
// be represented by a class called "Todo".
class Todos extends Table {
  IntColumn get id => integer().autoIncrement()();
  TextColumn get title => text().withLength(min: 6, max: 32)();
  TextColumn get content => text().named('body')();
  IntColumn get category => integer().nullable()();

// This will make moor generate a class called "Category" to represent a row in this table.
// By default, "Categorie" would have been used because it only strips away the trailing "s"
// in the table name.
class Categories extends Table {
  IntColumn get id => integer().autoIncrement()();
  TextColumn get description => text()();

// this annotation tells moor to prepare a database class that uses both of the
// tables we just defined. We'll see how to use that database class in a moment.
@UseMoor(tables: [Todos, Categories])
class MyDatabase {

⚠️ Note: The column definitions, the table name and the primary key must be known at compile time. For column definitions and the primary key, the function must use the => operator and can't contain anything more than what's included in the documentation and the examples. Otherwise, the generator won't be able to know what's going on.

Generating the code

Moor integrates with Dart's build system, so you can generate all the code needed with flutter packages pub run build_runner build. If you want to continuously rebuild the generated code where you change your code, run flutter packages pub run build_runner watch instead. After running either command once, the moor generator will have created a class for your database and data classes for your entities. To use it, change the MyDatabase class as follows:

// These imports are only needed to open the database
import 'package:moor/ffi.dart';
import 'package:path_provider/path_provider.dart';
import 'package:path/path.dart' as p;
import 'package:moor/moor.dart';
import 'dart:io';

LazyDatabase _openConnection() {
  // the LazyDatabase util lets us find the right location for the file async.
  return LazyDatabase(() async {
    // put the database file, called db.sqlite here, into the documents folder
    // for your app.
    final dbFolder = await getApplicationDocumentsDirectory();
    final file = File(p.join(dbFolder.path, 'db.sqlite'));
    return VmDatabase(file);

@UseMoor(tables: [Todos, Categories])
class MyDatabase extends _$MyDatabase {
  // we tell the database where to store the data with this constructor
  MyDatabase() : super(_openConnection());

  // you should bump this number whenever you change or add a table definition. Migrations
  // are covered later in this readme.
  int get schemaVersion => 1;

Congratulations! You're now ready to use all of moor. See the articles below for further reading. The "Writing queries" article contains everything you need to know to write selects, updates and inserts in moor!

Getting started with sql

Learn how to get started with the SQL version of moor, or how to migrate an existing project to moor.

Writing queries

Learn how to write database queries in pure Dart with moor

Dart tables

Further information on Dart tables