ktalanda/ReduxAndroid

State management library for Presentation Layer in Android application. Inspired by JS implementation of Redux.

This library is heavily inspired by Javascript implementation of Redux: https://github.com/reactjs/redux.

The library is intended to be used in Presentation layer of the application. Presenters shouldn't be talking to the IO devices such as Database or Network directly, but should use abstract interfaces to access data. Any change to the State will be accessible form any part of the app.

1. Description.

Library is based on unidirectional data flow. All the visual State of the application is stored in the Store. State can be modified only via Actions. State is an immutable object, so any time we make change to it we need to create new one by reducing it.

1.1. Elements of the library.

• Store - contains the visual State of the application represented by ViewModels. Via Reducer it reduces the actions and triggers the update event via reactive streams to any Presenter binded.
• Reducer - responsible for creating new state based on current state and passed action.
• Action - simple object which contains type of action and state to be updated.
• Presenter - creates the actions and dispatches them in the Store. It interacts with the View receiving interactions and updating it based on current application State. This is the place where the layer below should be called to interact with IO devices such as database, network etc.

2. Usage.

Sample usage can be found in the app module. It is an Android app using Dagger as a Dependency Injection framework. https://github.com/ktalanda/ReduxAndroid/tree/master/app/src/main/java/pl/k2net/ktalanda/maroubrascanner.

• Define ViewModels for your visual state. It should be a Data Class in Kotlin and has to implement ViewModel interface from redux library. https://github.com/ktalanda/ReduxAndroid/blob/master/app/src/main/java/pl/k2net/ktalanda/maroubrascanner/main/details/DetailsViewModel.kt

• Define Actions which represent every change that could happen in your UI. It has to implement Action interface from redux library and can contain extra information about the the state change. https://github.com/ktalanda/ReduxAndroid/blob/master/app/src/main/java/pl/k2net/ktalanda/maroubrascanner/main/details/UpdateDetailsListAction.kt

• Define Reducer which is responsible for changing the State based on passed Action. It has to extend Reducer class from redux library. https://github.com/ktalanda/ReduxAndroid/blob/master/app/src/main/java/pl/k2net/ktalanda/maroubrascanner/MaroubraReducer.kt

• Define Logger which is responsible for logs inside of the redux library. https://github.com/ktalanda/ReduxAndroid/blob/master/app/src/main/java/pl/k2net/ktalanda/maroubrascanner/AppLogger.kt

• Define Store as a Singleton somewhere in your application. Pass the Reducer, Logger and State via constructor. State is a simple Map where key has to be ViewModel class name, and value has to be the ViewModel itself. When creating the State object you are defining the default state of the application. In the sample app it is provided by dagger. https://github.com/ktalanda/ReduxAndroid/blob/master/app/src/main/java/pl/k2net/ktalanda/maroubrascanner/AppModule.kt#L24

• For every View create a Presenter which has to extend Presenter class from redux library. Store singleton instance has to be passed to the Presenter via constructor. It contains addToUpdateList method which allows to invoke list of actions on the update event. Each time update event arises it iterates over action list and clear invoked actions.

https://github.com/ktalanda/ReduxAndroid/blob/master/app/src/main/java/pl/k2net/ktalanda/maroubrascanner/main/MainPresenter.kt

License

MIT