selector example

Author: hoc081098

example/selector.dart

@@ -0,0 +1,198 @@
+import 'package:built_collection/built_collection.dart';
+import 'package:distinct_value_connectable_stream/distinct_value_connectable_stream.dart';
+import 'package:rx_redux/rx_redux.dart';
+
+//
+// [BEGIN] STATE
+//
+
+class Book {
+  final String id;
+  final String userId;
+  final String name;
+
+  Book(this.id, this.userId, this.name);
+
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+      other is Book &&
+          runtimeType == other.runtimeType &&
+          id == other.id &&
+          userId == other.userId &&
+          name == other.name;
+
+  @override
+  int get hashCode => id.hashCode ^ userId.hashCode ^ name.hashCode;
+
+  @override
+  String toString() => 'Book{id: $id, userId: $userId, name: $name}';
+}
+
+class User {
+  final String id;
+  final String name;
+
+  User(this.id, this.name);
+
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+      other is User &&
+          runtimeType == other.runtimeType &&
+          id == other.id &&
+          name == other.name;
+
+  @override
+  int get hashCode => id.hashCode ^ name.hashCode;
+
+  @override
+  String toString() => 'User{id: $id, name: $name}';
+}
+
+class State {
+  final User? selectedUser;
+  final BuiltList<Book> allBooks;
+  final Object? error;
+
+  State(this.selectedUser, this.allBooks, this.error);
+
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+      other is State &&
+          runtimeType == other.runtimeType &&
+          selectedUser == other.selectedUser &&
+          allBooks == other.allBooks &&
+          error == other.error;
+
+  @override
+  int get hashCode =>
+      selectedUser.hashCode ^ allBooks.hashCode ^ error.hashCode;
+
+  @override
+  String toString() =>
+      'State{selectedUser: $selectedUser, allBooks: $allBooks, error: $error}';
+}
+
+//
+// [END] STATE
+//
+
+//
+// [BEGIN] ACTION
+//
+
+abstract class Action {}
+
+class ChangeSelectedUserAction implements Action {
+  final User? user;
+
+  ChangeSelectedUserAction(this.user);
+}
+
+class AddBookAction implements Action {
+  final Book book;
+
+  AddBookAction(this.book);
+}
+
+class ErrorAction implements Action {
+  final Object error;
+
+  ErrorAction(this.error);
+}
+
+//
+// [END] ACTION
+//
+
+//
+// [BEGIN] DEMO
+//
+
+State reducer(State state, Action action) {
+  if (action is ChangeSelectedUserAction) {
+    return State(
+      action.user,
+      state.allBooks,
+      state.error,
+    );
+  }
+  if (action is AddBookAction) {
+    return State(
+      state.selectedUser,
+      state.allBooks.rebuild((b) => b.add(action.book)),
+      state.error,
+    );
+  }
+  if (action is ErrorAction) {
+    return State(
+      state.selectedUser,
+      state.allBooks,
+      action.error,
+    );
+  }
+
+  return state;
+}
+
+void main() async {
+  final store = RxReduxStore<Action, State>(
+      initialState: State(null, <Book>[].build(), null),
+      sideEffects: [],
+      reducer: reducer);
+
+  // select 2 pieces of state and combine them.
+  final visibleBooks$ = store.select2(
+    (s) => s.selectedUser?.id,
+    (s) => s.allBooks,
+    (String? userId, BuiltList<Book> books) {
+      print(
+          '<> Call projector with userId=${userId} and books=${books.length}');
+
+      return userId != null && books.isNotEmpty
+          ? books.where((b) => b.userId == userId).toBuiltList()
+          : books;
+    },
+  );
+
+  // logging state.
+  print('~> ${visibleBooks$.value}');
+  visibleBooks$.listen((s) => print('~> $s'));
+
+  // dispatch actions.
+  [
+    ChangeSelectedUserAction(User('0', 'Petrus')),
+    AddBookAction(Book('0', '0', 'Book 0')),
+    AddBookAction(Book('1', '0', 'Book 1')),
+    AddBookAction(Book('2', '0', 'Book 2')),
+    AddBookAction(Book('3', '0', 'Book 3')),
+  ].forEach(store.dispatch);
+  await Future<void>.delayed(const Duration(seconds: 1));
+  print('---------------------------------------------------');
+
+  [
+    ErrorAction('Error 1') /* has no effect */,
+    ChangeSelectedUserAction(
+        User('0', 'Hoc')) /* same user id -> has no effect */,
+    ChangeSelectedUserAction(
+        User('0', 'Nguyen')) /* same user id -> has no effect */,
+    ChangeSelectedUserAction(User('1', 'Hello')),
+    ErrorAction('Error 2') /* has no effect */,
+    AddBookAction(Book('4', '1', 'Book 4')),
+    ChangeSelectedUserAction(User('0', 'Rx redux 1')),
+    ChangeSelectedUserAction(
+        User('0', 'Rx redux 2')) /* same user id -> has no effect */,
+    ErrorAction('Error 3') /* has no effect */,
+  ].forEach(store.dispatch);
+  await Future<void>.delayed(const Duration(seconds: 1));
+  print('---------------------------------------------------');
+
+  // end by disposing store.
+  await store.dispose();
+}
+
+//
+// [END] DEMO
+//