Middleware

public protocol Middleware

Middleware protocol that represents a suas store middleware A middleware helps extending the dispatch logic of Suas.

A middleware can be used to implement:

• Logging that logs the state before and after the reducer changes it
• Perform async network calls and dispatches actions representing the result when the network returns.
• Other advanced usages…

Example

Implementing a logging middleware.

class LoggerMiddleware: Middleware {
  var api: MiddlewareAPI?
  var next: DispatchFunction?

  func onAction(action: Action, getState: @escaping GetStateFunction, dispatch: @escaping DispatchFunction, next: @escaping NextFunction) {
    // Read the state before any reducer changes it
    print("The old state is \(getState())")

    // Print the action
    print("The action is \(action)")

    // Continue the dispatching process..until the reducer reduces the action
    // Not calling `next` will prevent the action from reaching the reducer
    next?(action)

    // Read the state after any reducer changes it
    print("The new state is \(api?.state)")
  }
}