Cloud Firestore ODM使ってみた!

以前から興味あったので使って見ました!

今回もSoftware developerのKosukeさんの記事を参考にさせていただきました。
https://qiita.com/KosukeSaigusa/items/0ff9d84b966388dec53e

こちらが公式ドキュメント

https://firebase.flutter.dev/docs/firestore-odm/overview

Firebaseにプロジェクトをつくる。

今回はFirebase CLIを使ってiOS、Android、Web３つの環境を用意しました。

こちらを参考にしながら、環境構築していきます。
必要なパッケージを追加していく。追加し終わったのがこの状態

pubspec.yaml

name: odm_app
description: A new Flutter project.

# The following line prevents the package from being accidentally published to
# pub.dev using `flutter pub publish`. This is preferred for private packages.
publish_to: 'none' # Remove this line if you wish to publish to pub.dev

# The following defines the version and build number for your application.
# A version number is three numbers separated by dots, like 1.2.43
# followed by an optional build number separated by a +.
# Both the version and the builder number may be overridden in flutter
# build by specifying --build-name and --build-number, respectively.
# In Android, build-name is used as versionName while build-number used as versionCode.
# Read more about Android versioning at https://developer.android.com/studio/publish/versioning
# In iOS, build-name is used as CFBundleShortVersionString while build-number used as CFBundleVersion.
# Read more about iOS versioning at
# https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
version: 1.0.0+1

environment:
  sdk: ">=2.17.3 <3.0.0"

# Dependencies specify other packages that your package needs in order to work.
# To automatically upgrade your package dependencies to the latest versions
# consider running `flutter pub upgrade --major-versions`. Alternatively,
# dependencies can be manually updated by changing the version numbers below to
# the latest version available on pub.dev. To see which dependencies have newer
# versions available, run `flutter pub outdated`.
dependencies:
  flutter:
    sdk: flutter


  # The following adds the Cupertino Icons font to your application.
  # Use with the CupertinoIcons class for iOS style icons.
  cupertino_icons: ^1.0.2
  firebase_core: ^1.20.0
  cloud_firestore: ^3.4.3
  cloud_firestore_odm: ^1.0.0-dev.25
  json_annotation: ^4.6.0

dev_dependencies:
  flutter_test:
    sdk: flutter

  # The "flutter_lints" package below contains a set of recommended lints to
  # encourage good coding practices. The lint set provided by the package is
  # activated in the `analysis_options.yaml` file located at the root of your
  # package. See that file for information about deactivating specific lint
  # rules and activating additional ones.
  flutter_lints: ^2.0.0
  build_runner: ^2.2.0
  cloud_firestore_odm_generator: ^1.0.0-dev.25
  json_serializable: ^6.3.1

# For information on the generic Dart part of this file, see the
# following page: https://dart.dev/tools/pub/pubspec

# The following section is specific to Flutter packages.
flutter:

  # The following line ensures that the Material Icons font is
  # included with your application, so that you can use the icons in
  # the material Icons class.
  uses-material-design: true

  # To add assets to your application, add an assets section, like this:
  # assets:
  #   - images/a_dot_burr.jpeg
  #   - images/a_dot_ham.jpeg

  # An image asset can refer to one or more resolution-specific "variants", see
  # https://flutter.dev/assets-and-images/#resolution-aware

  # For details regarding adding assets from package dependencies, see
  # https://flutter.dev/assets-and-images/#from-packages

  # To add custom fonts to your application, add a fonts section here,
  # in this "flutter" section. Each entry in this list should have a
  # "family" key with the font family name, and a "fonts" key with a
  # list giving the asset and other descriptors for the font. For
  # example:
  # fonts:
  #   - family: Schyler
  #     fonts:
  #       - asset: fonts/Schyler-Regular.ttf
  #       - asset: fonts/Schyler-Italic.ttf
  #         style: italic
  #   - family: Trajan Pro
  #     fonts:
  #       - asset: fonts/TrajanPro.ttf
  #       - asset: fonts/TrajanPro_Bold.ttf
  #         weight: 700
  #
  # For details regarding fonts from package dependencies,
  # see https://flutter.dev/custom-fonts/#from-packages

今回はファイルが少ないのでこんな感じになっております。

モデルとなるファイルを作ります。Freezedより簡単かもしれないです?
でも、これ結構曲者で設定が必要みたいですね🤔
コードの保管機能で出てくるコードも違う?
今回は、ドキュメントのコードにTimestmp型を追加して見ました!
Timestmpを使うときは、Datetime型に変換する必要があります。出ないと人間には見ずらい表示になってしまう。

モデルとなるuser.dartを作成します。[part 'user.g.dart';]というコードは、ファイルと同じ名前でないといけません。コードを書いたら、ターミナルでコマンドを実行します。成功したらファイルが自動生成されます。

user.dart

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:json_annotation/json_annotation.dart';
import 'package:cloud_firestore_odm/cloud_firestore_odm.dart';

// This doesn't exist yet...! See "Next Steps"
part 'user.g.dart';

@JsonSerializable(explicitToJson: true)
class User {
  User({
    required this.name,
    required this.age,
    required this.email,
    this.createdAt // ?つけてるので、requiredいらない!
  });

  final String name;
  final int age;
  final String email;
  // TimestampConverter()と書くらしいがコードの保管機能で出てこなかった!
  @FirestoreTimestampConverter()
  Timestamp? createdAt;
}

@Collection<User>('users')
final usersRef = UserCollectionReference();

こちらのコマンドを実行する

flutter pub run build_runner build --delete-conflicting-outputs

user.g.dart

// GENERATED CODE - DO NOT MODIFY BY HAND

part of 'user.dart';

// **************************************************************************
// CollectionGenerator
// **************************************************************************

// GENERATED CODE - DO NOT MODIFY BY HAND
// ignore_for_file: unused_element, deprecated_member_use, deprecated_member_use_from_same_package, use_function_type_syntax_for_parameters, unnecessary_const, avoid_init_to_null, invalid_override_different_default_values_named, prefer_expression_function_bodies, annotate_overrides

class _Sentinel {
  const _Sentinel();
}

const _sentinel = _Sentinel();

/// A collection reference object can be used for adding documents,
/// getting document references, and querying for documents
/// (using the methods inherited from Query).
abstract class UserCollectionReference
    implements
        UserQuery,
        FirestoreCollectionReference<User, UserQuerySnapshot> {
  factory UserCollectionReference([
    FirebaseFirestore? firestore,
  ]) = _$UserCollectionReference;

  static User fromFirestore(
    DocumentSnapshot<Map<String, Object?>> snapshot,
    SnapshotOptions? options,
  ) {
    return _$UserFromJson(snapshot.data()!);
  }

  static Map<String, Object?> toFirestore(
    User value,
    SetOptions? options,
  ) {
    return _$UserToJson(value);
  }

  @override
  CollectionReference<User> get reference;

  @override
  UserDocumentReference doc([String? id]);

  /// Add a new document to this collection with the specified data,
  /// assigning it a document ID automatically.
  Future<UserDocumentReference> add(User value);
}

class _$UserCollectionReference extends _$UserQuery
    implements UserCollectionReference {
  factory _$UserCollectionReference([FirebaseFirestore? firestore]) {
    firestore ??= FirebaseFirestore.instance;

    return _$UserCollectionReference._(
      firestore.collection('users').withConverter(
            fromFirestore: UserCollectionReference.fromFirestore,
            toFirestore: UserCollectionReference.toFirestore,
          ),
    );
  }

  _$UserCollectionReference._(
    CollectionReference<User> reference,
  ) : super(reference, reference);

  String get path => reference.path;

  @override
  CollectionReference<User> get reference =>
      super.reference as CollectionReference<User>;

  @override
  UserDocumentReference doc([String? id]) {
    assert(
      id == null || id.split('/').length == 1,
      'The document ID cannot be from a different collection',
    );
    return UserDocumentReference(
      reference.doc(id),
    );
  }

  @override
  Future<UserDocumentReference> add(User value) {
    return reference.add(value).then((ref) => UserDocumentReference(ref));
  }

  @override
  bool operator ==(Object other) {
    return other is _$UserCollectionReference &&
        other.runtimeType == runtimeType &&
        other.reference == reference;
  }

  @override
  int get hashCode => Object.hash(runtimeType, reference);
}

abstract class UserDocumentReference
    extends FirestoreDocumentReference<User, UserDocumentSnapshot> {
  factory UserDocumentReference(DocumentReference<User> reference) =
      _$UserDocumentReference;

  DocumentReference<User> get reference;

  /// A reference to the [UserCollectionReference] containing this document.
  UserCollectionReference get parent {
    return _$UserCollectionReference(reference.firestore);
  }

  @override
  Stream<UserDocumentSnapshot> snapshots();

  @override
  Future<UserDocumentSnapshot> get([GetOptions? options]);

  @override
  Future<void> delete();

  Future<void> update({
    String name,
    int age,
    String email,
    Timestamp? createdAt,
  });

  Future<void> set(User value);
}

class _$UserDocumentReference
    extends FirestoreDocumentReference<User, UserDocumentSnapshot>
    implements UserDocumentReference {
  _$UserDocumentReference(this.reference);

  @override
  final DocumentReference<User> reference;

  /// A reference to the [UserCollectionReference] containing this document.
  UserCollectionReference get parent {
    return _$UserCollectionReference(reference.firestore);
  }

  @override
  Stream<UserDocumentSnapshot> snapshots() {
    return reference.snapshots().map((snapshot) {
      return UserDocumentSnapshot._(
        snapshot,
        snapshot.data(),
      );
    });
  }

  @override
  Future<UserDocumentSnapshot> get([GetOptions? options]) {
    return reference.get(options).then((snapshot) {
      return UserDocumentSnapshot._(
        snapshot,
        snapshot.data(),
      );
    });
  }

  @override
  Future<void> delete() {
    return reference.delete();
  }

  Future<void> update({
    Object? name = _sentinel,
    Object? age = _sentinel,
    Object? email = _sentinel,
    Object? createdAt = _sentinel,
  }) async {
    final json = {
      if (name != _sentinel) "name": name as String,
      if (age != _sentinel) "age": age as int,
      if (email != _sentinel) "email": email as String,
      if (createdAt != _sentinel) "createdAt": createdAt as Timestamp?,
    };

    return reference.update(json);
  }

  Future<void> set(User value) {
    return reference.set(value);
  }

  @override
  bool operator ==(Object other) {
    return other is UserDocumentReference &&
        other.runtimeType == runtimeType &&
        other.parent == parent &&
        other.id == id;
  }

  @override
  int get hashCode => Object.hash(runtimeType, parent, id);
}

class UserDocumentSnapshot extends FirestoreDocumentSnapshot<User> {
  UserDocumentSnapshot._(
    this.snapshot,
    this.data,
  );

  @override
  final DocumentSnapshot<User> snapshot;

  @override
  UserDocumentReference get reference {
    return UserDocumentReference(
      snapshot.reference,
    );
  }

  @override
  final User? data;
}

abstract class UserQuery implements QueryReference<User, UserQuerySnapshot> {
  @override
  UserQuery limit(int limit);

  @override
  UserQuery limitToLast(int limit);

  /// Perform an order query based on a [FieldPath].
  ///
  /// This method is considered unsafe as it does check that the field path
  /// maps to a valid property or that parameters such as [isEqualTo] receive
  /// a value of the correct type.
  ///
  /// If possible, instead use the more explicit variant of order queries:
  ///
  /// **AVOID**:
  /// ```dart
  /// collection.orderByFieldPath(
  ///   FieldPath.fromString('title'),
  ///   startAt: 'title',
  /// );
  /// ```
  ///
  /// **PREFER**:
  /// ```dart
  /// collection.orderByTitle(startAt: 'title');
  /// ```
  UserQuery orderByFieldPath(
    FieldPath fieldPath, {
    bool descending = false,
    Object? startAt,
    Object? startAfter,
    Object? endAt,
    Object? endBefore,
    UserDocumentSnapshot? startAtDocument,
    UserDocumentSnapshot? endAtDocument,
    UserDocumentSnapshot? endBeforeDocument,
    UserDocumentSnapshot? startAfterDocument,
  });

  /// Perform a where query based on a [FieldPath].
  ///
  /// This method is considered unsafe as it does check that the field path
  /// maps to a valid property or that parameters such as [isEqualTo] receive
  /// a value of the correct type.
  ///
  /// If possible, instead use the more explicit variant of where queries:
  ///
  /// **AVOID**:
  /// ```dart
  /// collection.whereFieldPath(FieldPath.fromString('title'), isEqualTo: 'title');
  /// ```
  ///
  /// **PREFER**:
  /// ```dart
  /// collection.whereTitle(isEqualTo: 'title');
  /// ```
  UserQuery whereFieldPath(
    FieldPath fieldPath, {
    Object? isEqualTo,
    Object? isNotEqualTo,
    Object? isLessThan,
    Object? isLessThanOrEqualTo,
    Object? isGreaterThan,
    Object? isGreaterThanOrEqualTo,
    Object? arrayContains,
    List<Object?>? arrayContainsAny,
    List<Object?>? whereIn,
    List<Object?>? whereNotIn,
    bool? isNull,
  });

  UserQuery whereDocumentId({
    String? isEqualTo,
    String? isNotEqualTo,
    String? isLessThan,
    String? isLessThanOrEqualTo,
    String? isGreaterThan,
    String? isGreaterThanOrEqualTo,
    bool? isNull,
    List<String>? whereIn,
    List<String>? whereNotIn,
  });
  UserQuery whereName({
    String? isEqualTo,
    String? isNotEqualTo,
    String? isLessThan,
    String? isLessThanOrEqualTo,
    String? isGreaterThan,
    String? isGreaterThanOrEqualTo,
    bool? isNull,
    List<String>? whereIn,
    List<String>? whereNotIn,
  });
  UserQuery whereAge({
    int? isEqualTo,
    int? isNotEqualTo,
    int? isLessThan,
    int? isLessThanOrEqualTo,
    int? isGreaterThan,
    int? isGreaterThanOrEqualTo,
    bool? isNull,
    List<int>? whereIn,
    List<int>? whereNotIn,
  });
  UserQuery whereEmail({
    String? isEqualTo,
    String? isNotEqualTo,
    String? isLessThan,
    String? isLessThanOrEqualTo,
    String? isGreaterThan,
    String? isGreaterThanOrEqualTo,
    bool? isNull,
    List<String>? whereIn,
    List<String>? whereNotIn,
  });
  UserQuery whereCreatedAt({
    Timestamp? isEqualTo,
    Timestamp? isNotEqualTo,
    Timestamp? isLessThan,
    Timestamp? isLessThanOrEqualTo,
    Timestamp? isGreaterThan,
    Timestamp? isGreaterThanOrEqualTo,
    bool? isNull,
    List<Timestamp?>? whereIn,
    List<Timestamp?>? whereNotIn,
  });

  UserQuery orderByDocumentId({
    bool descending = false,
    String startAt,
    String startAfter,
    String endAt,
    String endBefore,
    UserDocumentSnapshot? startAtDocument,
    UserDocumentSnapshot? endAtDocument,
    UserDocumentSnapshot? endBeforeDocument,
    UserDocumentSnapshot? startAfterDocument,
  });

  UserQuery orderByName({
    bool descending = false,
    String startAt,
    String startAfter,
    String endAt,
    String endBefore,
    UserDocumentSnapshot? startAtDocument,
    UserDocumentSnapshot? endAtDocument,
    UserDocumentSnapshot? endBeforeDocument,
    UserDocumentSnapshot? startAfterDocument,
  });

  UserQuery orderByAge({
    bool descending = false,
    int startAt,
    int startAfter,
    int endAt,
    int endBefore,
    UserDocumentSnapshot? startAtDocument,
    UserDocumentSnapshot? endAtDocument,
    UserDocumentSnapshot? endBeforeDocument,
    UserDocumentSnapshot? startAfterDocument,
  });

  UserQuery orderByEmail({
    bool descending = false,
    String startAt,
    String startAfter,
    String endAt,
    String endBefore,
    UserDocumentSnapshot? startAtDocument,
    UserDocumentSnapshot? endAtDocument,
    UserDocumentSnapshot? endBeforeDocument,
    UserDocumentSnapshot? startAfterDocument,
  });

  UserQuery orderByCreatedAt({
    bool descending = false,
    Timestamp? startAt,
    Timestamp? startAfter,
    Timestamp? endAt,
    Timestamp? endBefore,
    UserDocumentSnapshot? startAtDocument,
    UserDocumentSnapshot? endAtDocument,
    UserDocumentSnapshot? endBeforeDocument,
    UserDocumentSnapshot? startAfterDocument,
  });
}

class _$UserQuery extends QueryReference<User, UserQuerySnapshot>
    implements UserQuery {
  _$UserQuery(
    this.reference,
    this._collection,
  );

  final CollectionReference<Object?> _collection;

  @override
  final Query<User> reference;

  get _$UserFieldMap => null;

  UserQuerySnapshot _decodeSnapshot(
    QuerySnapshot<User> snapshot,
  ) {
    final docs = snapshot.docs.map((e) {
      return UserQueryDocumentSnapshot._(e, e.data());
    }).toList();

    final docChanges = snapshot.docChanges.map((change) {
      return FirestoreDocumentChange<UserDocumentSnapshot>(
        type: change.type,
        oldIndex: change.oldIndex,
        newIndex: change.newIndex,
        doc: UserDocumentSnapshot._(change.doc, change.doc.data()),
      );
    }).toList();

    return UserQuerySnapshot._(
      snapshot,
      docs,
      docChanges,
    );
  }

  @override
  Stream<UserQuerySnapshot> snapshots([SnapshotOptions? options]) {
    return reference.snapshots().map(_decodeSnapshot);
  }

  @override
  Future<UserQuerySnapshot> get([GetOptions? options]) {
    return reference.get(options).then(_decodeSnapshot);
  }

  @override
  UserQuery limit(int limit) {
    return _$UserQuery(
      reference.limit(limit),
      _collection,
    );
  }

  @override
  UserQuery limitToLast(int limit) {
    return _$UserQuery(
      reference.limitToLast(limit),
      _collection,
    );
  }

  UserQuery orderByFieldPath(
    FieldPath fieldPath, {
    bool descending = false,
    Object? startAt = _sentinel,
    Object? startAfter = _sentinel,
    Object? endAt = _sentinel,
    Object? endBefore = _sentinel,
    UserDocumentSnapshot? startAtDocument,
    UserDocumentSnapshot? endAtDocument,
    UserDocumentSnapshot? endBeforeDocument,
    UserDocumentSnapshot? startAfterDocument,
  }) {
    var query = reference.orderBy(fieldPath, descending: descending);

    if (startAtDocument != null) {
      query = query.startAtDocument(startAtDocument.snapshot);
    }
    if (startAfterDocument != null) {
      query = query.startAfterDocument(startAfterDocument.snapshot);
    }
    if (endAtDocument != null) {
      query = query.endAtDocument(endAtDocument.snapshot);
    }
    if (endBeforeDocument != null) {
      query = query.endBeforeDocument(endBeforeDocument.snapshot);
    }

    if (startAt != _sentinel) {
      query = query.startAt([startAt]);
    }
    if (startAfter != _sentinel) {
      query = query.startAfter([startAfter]);
    }
    if (endAt != _sentinel) {
      query = query.endAt([endAt]);
    }
    if (endBefore != _sentinel) {
      query = query.endBefore([endBefore]);
    }

    return _$UserQuery(query, _collection);
  }

  UserQuery whereFieldPath(
    FieldPath fieldPath, {
    Object? isEqualTo,
    Object? isNotEqualTo,
    Object? isLessThan,
    Object? isLessThanOrEqualTo,
    Object? isGreaterThan,
    Object? isGreaterThanOrEqualTo,
    Object? arrayContains,
    List<Object?>? arrayContainsAny,
    List<Object?>? whereIn,
    List<Object?>? whereNotIn,
    bool? isNull,
  }) {
    return _$UserQuery(
      reference.where(
        fieldPath,
        isEqualTo: isEqualTo,
        isNotEqualTo: isNotEqualTo,
        isLessThan: isLessThan,
        isLessThanOrEqualTo: isLessThanOrEqualTo,
        isGreaterThan: isGreaterThan,
        isGreaterThanOrEqualTo: isGreaterThanOrEqualTo,
        arrayContains: arrayContains,
        arrayContainsAny: arrayContainsAny,
        whereIn: whereIn,
        whereNotIn: whereNotIn,
        isNull: isNull,
      ),
      _collection,
    );
  }

  UserQuery whereDocumentId({
    String? isEqualTo,
    String? isNotEqualTo,
    String? isLessThan,
    String? isLessThanOrEqualTo,
    String? isGreaterThan,
    String? isGreaterThanOrEqualTo,
    bool? isNull,
    List<String>? whereIn,
    List<String>? whereNotIn,
  }) {
    return _$UserQuery(
      reference.where(
        FieldPath.documentId,
        isEqualTo: isEqualTo,
        isNotEqualTo: isNotEqualTo,
        isLessThan: isLessThan,
        isLessThanOrEqualTo: isLessThanOrEqualTo,
        isGreaterThan: isGreaterThan,
        isGreaterThanOrEqualTo: isGreaterThanOrEqualTo,
        isNull: isNull,
        whereIn: whereIn,
        whereNotIn: whereNotIn,
      ),
      _collection,
    );
  }

  UserQuery whereName({
    String? isEqualTo,
    String? isNotEqualTo,
    String? isLessThan,
    String? isLessThanOrEqualTo,
    String? isGreaterThan,
    String? isGreaterThanOrEqualTo,
    bool? isNull,
    List<String>? whereIn,
    List<String>? whereNotIn,
  }) {
    return _$UserQuery(
      reference.where(
        _$UserFieldMap["name"]!,
        isEqualTo: isEqualTo,
        isNotEqualTo: isNotEqualTo,
        isLessThan: isLessThan,
        isLessThanOrEqualTo: isLessThanOrEqualTo,
        isGreaterThan: isGreaterThan,
        isGreaterThanOrEqualTo: isGreaterThanOrEqualTo,
        isNull: isNull,
        whereIn: whereIn,
        whereNotIn: whereNotIn,
      ),
      _collection,
    );
  }

  UserQuery whereAge({
    int? isEqualTo,
    int? isNotEqualTo,
    int? isLessThan,
    int? isLessThanOrEqualTo,
    int? isGreaterThan,
    int? isGreaterThanOrEqualTo,
    bool? isNull,
    List<int>? whereIn,
    List<int>? whereNotIn,
  }) {
    return _$UserQuery(
      reference.where(
        _$UserFieldMap["age"]!,
        isEqualTo: isEqualTo,
        isNotEqualTo: isNotEqualTo,
        isLessThan: isLessThan,
        isLessThanOrEqualTo: isLessThanOrEqualTo,
        isGreaterThan: isGreaterThan,
        isGreaterThanOrEqualTo: isGreaterThanOrEqualTo,
        isNull: isNull,
        whereIn: whereIn,
        whereNotIn: whereNotIn,
      ),
      _collection,
    );
  }

  UserQuery whereEmail({
    String? isEqualTo,
    String? isNotEqualTo,
    String? isLessThan,
    String? isLessThanOrEqualTo,
    String? isGreaterThan,
    String? isGreaterThanOrEqualTo,
    bool? isNull,
    List<String>? whereIn,
    List<String>? whereNotIn,
  }) {
    return _$UserQuery(
      reference.where(
        _$UserFieldMap["email"]!,
        isEqualTo: isEqualTo,
        isNotEqualTo: isNotEqualTo,
        isLessThan: isLessThan,
        isLessThanOrEqualTo: isLessThanOrEqualTo,
        isGreaterThan: isGreaterThan,
        isGreaterThanOrEqualTo: isGreaterThanOrEqualTo,
        isNull: isNull,
        whereIn: whereIn,
        whereNotIn: whereNotIn,
      ),
      _collection,
    );
  }

  UserQuery whereCreatedAt({
    Timestamp? isEqualTo,
    Timestamp? isNotEqualTo,
    Timestamp? isLessThan,
    Timestamp? isLessThanOrEqualTo,
    Timestamp? isGreaterThan,
    Timestamp? isGreaterThanOrEqualTo,
    bool? isNull,
    List<Timestamp?>? whereIn,
    List<Timestamp?>? whereNotIn,
  }) {
    return _$UserQuery(
      reference.where(
        _$UserFieldMap["createdAt"]!,
        isEqualTo: isEqualTo,
        isNotEqualTo: isNotEqualTo,
        isLessThan: isLessThan,
        isLessThanOrEqualTo: isLessThanOrEqualTo,
        isGreaterThan: isGreaterThan,
        isGreaterThanOrEqualTo: isGreaterThanOrEqualTo,
        isNull: isNull,
        whereIn: whereIn,
        whereNotIn: whereNotIn,
      ),
      _collection,
    );
  }

  UserQuery orderByDocumentId({
    bool descending = false,
    Object? startAt = _sentinel,
    Object? startAfter = _sentinel,
    Object? endAt = _sentinel,
    Object? endBefore = _sentinel,
    UserDocumentSnapshot? startAtDocument,
    UserDocumentSnapshot? endAtDocument,
    UserDocumentSnapshot? endBeforeDocument,
    UserDocumentSnapshot? startAfterDocument,
  }) {
    var query = reference.orderBy(FieldPath.documentId, descending: descending);

    if (startAtDocument != null) {
      query = query.startAtDocument(startAtDocument.snapshot);
    }
    if (startAfterDocument != null) {
      query = query.startAfterDocument(startAfterDocument.snapshot);
    }
    if (endAtDocument != null) {
      query = query.endAtDocument(endAtDocument.snapshot);
    }
    if (endBeforeDocument != null) {
      query = query.endBeforeDocument(endBeforeDocument.snapshot);
    }

    if (startAt != _sentinel) {
      query = query.startAt([startAt]);
    }
    if (startAfter != _sentinel) {
      query = query.startAfter([startAfter]);
    }
    if (endAt != _sentinel) {
      query = query.endAt([endAt]);
    }
    if (endBefore != _sentinel) {
      query = query.endBefore([endBefore]);
    }

    return _$UserQuery(query, _collection);
  }

  UserQuery orderByName({
    bool descending = false,
    Object? startAt = _sentinel,
    Object? startAfter = _sentinel,
    Object? endAt = _sentinel,
    Object? endBefore = _sentinel,
    UserDocumentSnapshot? startAtDocument,
    UserDocumentSnapshot? endAtDocument,
    UserDocumentSnapshot? endBeforeDocument,
    UserDocumentSnapshot? startAfterDocument,
  }) {
    var query =
        reference.orderBy(_$UserFieldMap["name"]!, descending: descending);

    if (startAtDocument != null) {
      query = query.startAtDocument(startAtDocument.snapshot);
    }
    if (startAfterDocument != null) {
      query = query.startAfterDocument(startAfterDocument.snapshot);
    }
    if (endAtDocument != null) {
      query = query.endAtDocument(endAtDocument.snapshot);
    }
    if (endBeforeDocument != null) {
      query = query.endBeforeDocument(endBeforeDocument.snapshot);
    }

    if (startAt != _sentinel) {
      query = query.startAt([startAt]);
    }
    if (startAfter != _sentinel) {
      query = query.startAfter([startAfter]);
    }
    if (endAt != _sentinel) {
      query = query.endAt([endAt]);
    }
    if (endBefore != _sentinel) {
      query = query.endBefore([endBefore]);
    }

    return _$UserQuery(query, _collection);
  }

  UserQuery orderByAge({
    bool descending = false,
    Object? startAt = _sentinel,
    Object? startAfter = _sentinel,
    Object? endAt = _sentinel,
    Object? endBefore = _sentinel,
    UserDocumentSnapshot? startAtDocument,
    UserDocumentSnapshot? endAtDocument,
    UserDocumentSnapshot? endBeforeDocument,
    UserDocumentSnapshot? startAfterDocument,
  }) {
    var query =
        reference.orderBy(_$UserFieldMap["age"]!, descending: descending);

    if (startAtDocument != null) {
      query = query.startAtDocument(startAtDocument.snapshot);
    }
    if (startAfterDocument != null) {
      query = query.startAfterDocument(startAfterDocument.snapshot);
    }
    if (endAtDocument != null) {
      query = query.endAtDocument(endAtDocument.snapshot);
    }
    if (endBeforeDocument != null) {
      query = query.endBeforeDocument(endBeforeDocument.snapshot);
    }

    if (startAt != _sentinel) {
      query = query.startAt([startAt]);
    }
    if (startAfter != _sentinel) {
      query = query.startAfter([startAfter]);
    }
    if (endAt != _sentinel) {
      query = query.endAt([endAt]);
    }
    if (endBefore != _sentinel) {
      query = query.endBefore([endBefore]);
    }

    return _$UserQuery(query, _collection);
  }

  UserQuery orderByEmail({
    bool descending = false,
    Object? startAt = _sentinel,
    Object? startAfter = _sentinel,
    Object? endAt = _sentinel,
    Object? endBefore = _sentinel,
    UserDocumentSnapshot? startAtDocument,
    UserDocumentSnapshot? endAtDocument,
    UserDocumentSnapshot? endBeforeDocument,
    UserDocumentSnapshot? startAfterDocument,
  }) {
    var query =
        reference.orderBy(_$UserFieldMap["email"]!, descending: descending);

    if (startAtDocument != null) {
      query = query.startAtDocument(startAtDocument.snapshot);
    }
    if (startAfterDocument != null) {
      query = query.startAfterDocument(startAfterDocument.snapshot);
    }
    if (endAtDocument != null) {
      query = query.endAtDocument(endAtDocument.snapshot);
    }
    if (endBeforeDocument != null) {
      query = query.endBeforeDocument(endBeforeDocument.snapshot);
    }

    if (startAt != _sentinel) {
      query = query.startAt([startAt]);
    }
    if (startAfter != _sentinel) {
      query = query.startAfter([startAfter]);
    }
    if (endAt != _sentinel) {
      query = query.endAt([endAt]);
    }
    if (endBefore != _sentinel) {
      query = query.endBefore([endBefore]);
    }

    return _$UserQuery(query, _collection);
  }

  UserQuery orderByCreatedAt({
    bool descending = false,
    Object? startAt = _sentinel,
    Object? startAfter = _sentinel,
    Object? endAt = _sentinel,
    Object? endBefore = _sentinel,
    UserDocumentSnapshot? startAtDocument,
    UserDocumentSnapshot? endAtDocument,
    UserDocumentSnapshot? endBeforeDocument,
    UserDocumentSnapshot? startAfterDocument,
  }) {
    var query =
        reference.orderBy(_$UserFieldMap["createdAt"]!, descending: descending);

    if (startAtDocument != null) {
      query = query.startAtDocument(startAtDocument.snapshot);
    }
    if (startAfterDocument != null) {
      query = query.startAfterDocument(startAfterDocument.snapshot);
    }
    if (endAtDocument != null) {
      query = query.endAtDocument(endAtDocument.snapshot);
    }
    if (endBeforeDocument != null) {
      query = query.endBeforeDocument(endBeforeDocument.snapshot);
    }

    if (startAt != _sentinel) {
      query = query.startAt([startAt]);
    }
    if (startAfter != _sentinel) {
      query = query.startAfter([startAfter]);
    }
    if (endAt != _sentinel) {
      query = query.endAt([endAt]);
    }
    if (endBefore != _sentinel) {
      query = query.endBefore([endBefore]);
    }

    return _$UserQuery(query, _collection);
  }

  @override
  bool operator ==(Object other) {
    return other is _$UserQuery &&
        other.runtimeType == runtimeType &&
        other.reference == reference;
  }

  @override
  int get hashCode => Object.hash(runtimeType, reference);
}

class UserQuerySnapshot
    extends FirestoreQuerySnapshot<User, UserQueryDocumentSnapshot> {
  UserQuerySnapshot._(
    this.snapshot,
    this.docs,
    this.docChanges,
  );

  final QuerySnapshot<User> snapshot;

  @override
  final List<UserQueryDocumentSnapshot> docs;

  @override
  final List<FirestoreDocumentChange<UserDocumentSnapshot>> docChanges;
}

class UserQueryDocumentSnapshot extends FirestoreQueryDocumentSnapshot<User>
    implements UserDocumentSnapshot {
  UserQueryDocumentSnapshot._(this.snapshot, this.data);

  @override
  final QueryDocumentSnapshot<User> snapshot;

  @override
  UserDocumentReference get reference {
    return UserDocumentReference(snapshot.reference);
  }

  @override
  final User data;
}

// **************************************************************************
// JsonSerializableGenerator
// **************************************************************************

User _$UserFromJson(Map<String, dynamic> json) => User(
      name: json['name'] as String,
      age: json['age'] as int,
      email: json['email'] as String,
      createdAt: _$JsonConverterFromJson<Timestamp, Timestamp>(
          json['createdAt'], const FirestoreTimestampConverter().fromJson),
    );

Map<String, dynamic> _$UserToJson(User instance) => <String, dynamic>{
      'name': instance.name,
      'age': instance.age,
      'email': instance.email,
      'createdAt': _$JsonConverterToJson<Timestamp, Timestamp>(
          instance.createdAt, const FirestoreTimestampConverter().toJson),
    };

Value? _$JsonConverterFromJson<Json, Value>(
  Object? json,
  Value? Function(Json json) fromJson,
) =>
    json == null ? null : fromJson(json as Json);

Json? _$JsonConverterToJson<Json, Value>(
  Value? value,
  Json? Function(Value value) toJson,
) =>
    value == null ? null : toJson(value);

エディタやIDEの機能を使ってgetterを追加しないとエラーが消えないので、追加します。
これでいいのか疑問😅

アプリ側のプログラムはこのようになっております
main.dart

import 'package:cloud_firestore_odm/cloud_firestore_odm.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:flutter/material.dart';
import 'package:odm_app/firebase_options.dart';
import 'package:odm_app/user.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp(
    options: DefaultFirebaseOptions.currentPlatform,
  );
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: UsersList(),
    );
  }
}

class UsersList extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Cloud FireStore ODM'),
      ),
      body: Center(
        child: FirestoreBuilder<UserQuerySnapshot>(
            ref: usersRef,
            builder: (context, AsyncSnapshot<UserQuerySnapshot> snapshot,
                Widget? child) {
              if (snapshot.hasError) return Text('Something went wrong!');
              if (!snapshot.hasData) return Text('Loading users...');

              // Access the QuerySnapshot
              UserQuerySnapshot querySnapshot = snapshot.requireData;

              return ListView.builder(
                itemCount: querySnapshot.docs.length,
                itemBuilder: (context, index) {
                  // Access the User instance
                  User user = querySnapshot.docs[index].data;
                  // createdAtの後に?.toDate()をつけてDateTimeへ変換する
                  // DateTimeへ変換するに変換しないと、人間の目には見ずらい時間が表示される!
                  return Text('User name: ${user.email}, age ${user.createdAt?.toDate()}');
                },
              );
            }),
      ),
    );
  }
}

Flutter WebでビルドするとFireStroeの値を取得できているのを確認できました。
こちらは修正前の画面。時間が見ずらい!

こちらが修正後の画面。見やすくなりました。

表示する情報を増やしたいので、TextWidgetをWrapして、レイアウト変更してみます。最初これやってた時に何故か途中で表示できなくなった?
私物のintelのMacでは問題ない?、やり方が良くなかった🤔
データも追加してみた。最初使って見た時何故かwarningなんとかってエラーが、画面に表示される?
今はない。なぜだ....

main.dart

import 'package:cloud_firestore_odm/cloud_firestore_odm.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:flutter/material.dart';
import 'package:odm_app/firebase_options.dart';
import 'package:odm_app/user.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp(
    options: DefaultFirebaseOptions.currentPlatform,
  );
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: UsersList(),
    );
  }
}

class UsersList extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Cloud FireStore ODM'),
      ),
      body: Center(
        child: FirestoreBuilder<UserQuerySnapshot>(
            ref: usersRef,
            builder: (context, AsyncSnapshot<UserQuerySnapshot> snapshot,
                Widget? child) {
              if (snapshot.hasError) return Text('Something went wrong!');
              if (!snapshot.hasData) return Text('Loading users...');

              // Access the QuerySnapshot
              UserQuerySnapshot querySnapshot = snapshot.requireData;

              return ListView.builder(
                itemCount: querySnapshot.docs.length,
                itemBuilder: (context, index) {
                  // Access the User instance
                  User user = querySnapshot.docs[index].data;
                  // createdAtの後に?.toDate()をつけてDateTimeへ変換する
                  // DateTimeへ変換するに変換しないと、人間の目には見ずらい時間が表示される!
                  return Column(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: [
                      SizedBox(height: 40),
                      Text('User name: ${user.name}, age ${user.age}'),
                      Text('User name: ${user.email}, age ${user.createdAt?.toDate()}'),
                      SizedBox(height: 20),
                    ],
                  );
                },
              );
            }),
      ),
    );
  }
}

iOSでbuildする。見た目が崩れるので、文字を減らして日本語の表示に変えました。

使って見た感想

Freezedと違ってTimestmpConverterなるクラスを作らなくてもよくて、@の後に決まったコードを書くといい感じでやってくれるみたいです。以前はTimestmp型への対応がされていなかったそうです。
まだ、試作品らしく不具合が多いかもしれないですね🤔
でも、人気があるみたいでこれから流行っていくのだろうと思います。私も積極的に使っていきたいですね。
toMapとかtoJSONと毎回かくの大変でして、できれば自動化したいです😇