add TypedMiddlewareBase abstraction

CHANGELOG.md

@@ -1,8 +1,12 @@
-5.0.0
+# 5.1.0
+
+  * Added option to create typed middelware class by extending `TypedMiddlewareBase<State, Action>`
+
+# 5.0.0
 
   * Preview version, same as 5.0.0-nullsafety
 
-5.0.0-nullsafety
+# 5.0.0-nullsafety
 
   * Update to null safety
   * Drop package:coverage

README.md

@@ -100,12 +100,22 @@ loggingMiddleware(Store<int> store, action, NextDispatcher next) {
   next(action);
 }
 
+// You can also create a middleware class bound to exact action type.
+class CallMiddleware extends TypedMiddlewareBase<State, CallAction> {
+  @override
+  dynamic dispatch(
+      Store<String> store, CallAction action, NextDispatcher next) {
+    service.call(action.phone);
+    next(action);
+  }
+}
+
 main() {
   // Create the store with our Reducer and Middleware
   final store = new Store<int>(
     counterReducer, 
     initialState: 0, 
-    middleware: [loggingMiddleware],
+    middleware: [loggingMiddleware, CallMiddleware()],
   );
 
   // Render our State right away

lib/src/utils.dart

@@ -115,6 +115,50 @@ class TypedReducer<State, Action> implements ReducerClass<State> {
   }
 }
 
+/// A convenience type to build a Middleware to an Action
+/// of a specific type. Allows for Type Safe Middleware.
+///
+/// ### Example
+/// ```
+/// class CustomMiddleware extends TypedMiddlewareBase<AppState, CustomAction> {
+///   @override
+///   dynamic dispatch(
+///     Store<AppState> store,
+///     CustomAction action,
+///     NextDispatcher next,
+///   ) {
+///     next(action);
+///   }
+/// }
+/// ```
+/// We will then wire up specific types of actions to a List of Middleware
+/// that handle those actions.
+/// ```
+/// final List<Middleware<AppState>> middleware = [
+///   CallMiddleware(),
+///   LoginMiddleware(),
+///   LogoutMiddleware(),
+/// ];
+/// ```
+abstract class TypedMiddlewareBase<State, Action>
+    implements MiddlewareClass<State> {
+  /// A [Middleware] function that only works on actions of a specific type.
+  dynamic dispatch(
+    Store<State> store,
+    Action action,
+    NextDispatcher next,
+  );
+
+  @override
+  dynamic call(Store<State> store, dynamic action, NextDispatcher next) {
+    if (action is Action) {
+      return dispatch(store, action, next);
+    } else {
+      return next(action);
+    }
+  }
+}
+
 /// A convenience type for binding a piece of Middleware to an Action
 /// of a specific type. Allows for Type Safe Middleware and reduces boilerplate.
 ///
@@ -211,7 +255,8 @@ class TypedReducer<State, Action> implements ReducerClass<State> {
 ///   new TypedMiddleware<AppState, TodosLoadedAction>(saveItemsMiddleware),
 /// ];
 /// ```
-class TypedMiddleware<State, Action> implements MiddlewareClass<State> {
+class TypedMiddleware<State, Action>
+    extends TypedMiddlewareBase<State, Action> {
   /// A [Middleware] function that only works on actions of a specific type.
   final dynamic Function(
     Store<State> store,
@@ -224,13 +269,8 @@ class TypedMiddleware<State, Action> implements MiddlewareClass<State> {
   TypedMiddleware(this.middleware);
 
   @override
-  dynamic call(Store<State> store, dynamic action, NextDispatcher next) {
-    if (action is Action) {
-      return middleware(store, action, next);
-    } else {
-      return next(action);
-    }
-  }
+  dynamic dispatch(Store<State> store, Action action, NextDispatcher next) =>
+      middleware(store, action, next);
 }
 
 /// Defines a utility function that combines several reducers.

test/test_data.dart

@@ -89,8 +89,18 @@ class ThunkMiddleware<State> implements MiddlewareClass<State> {
   }
 }
 
+class TypedTestMiddleware extends TypedMiddlewareBase<String, TypedTestAction> {
+  @override
+  dynamic dispatch(
+      Store<String> store, TypedTestAction action, NextDispatcher next) {
+    next('TypedTestMiddleware called');
+  }
+}
+
 class TestAction1 {}
 
 class TestAction2 {}
 
 class TestAction3 {}
+
+class TypedTestAction {}

test/utils_test.dart

@@ -108,6 +108,7 @@ void main() {
         middleware: [
           TypedMiddleware<String, TestAction1>(testAction1Middleware),
           TypedMiddleware<String, TestAction2>(testAction2Middleware),
+          TypedTestMiddleware(),
         ],
       );
 
@@ -116,6 +117,9 @@ void main() {
 
       store.dispatch(TestAction2());
       expect(store.state, 'testAction2Middleware called');
+
+      store.dispatch(TypedTestAction());
+      expect(store.state, 'TypedTestMiddleware called');
     });
 
     test(
@@ -127,6 +131,7 @@ void main() {
         initialState: initialState,
         middleware: [
           TypedMiddleware<String, TestAction1>(testAction1Middleware),
+          TypedTestMiddleware(),
         ],
       );