KAction - a port of RxSwiftCommunity/Action

An KAction is a way to say "hey, later I'll need you to subscribe to this thing." It's actually a lot more involved than that.

KActions accept a workFactory: a closure that takes some input and produces an observable. When execute() is called, it passes its parameter to this closure and subscribes to the work.

• Can only be executed while "enabled" (true if unspecified).
• Only execute one thing at a time.
• Aggregates next/error events across individual executions.

Oh, and it has this really nice thing with Button that's pretty cool. It'll manage the button's enabled state, make sure the button is disabled while your work is being done, all that stuff 👍

Works perfectly with RxBinding

Usage

You have to pass a workFactory that takes input and returns an Observable. This represents some work that needs to be accomplished. Whenever you call execute(), you pass in input that's fed to the work factory. The Action will subscribe to the observable and emit the Next events on its elements property. If the observable errors, the error is sent as a Next even on the errors property. Neat.

KActions can only execute one thing at a time. If you try to execute an action that's currently executing, you'll get an error. The executing property sends true and false values as Next events.

val kaction = KAction<String, Boolean>(input, {
    networkLibrary.checkEmailExists(input)
})
...
kaction.execute("ash@ashfurrow.com")

Notice that the first generic parameter is the type of the input, and the second is the type of observable that workFactory creates. You can think of it a bit like the action's "output."

You can also specify an enabledIf parameter to the KAction initializer.

val isEmailValid: Observable<Boolean> = RxTextView.textChanges(emailTextView).map(this::isValidEmail())

val kaction = KAction<String, Boolean>(input, {
    networkLibrary.checkEmailExists(input)
}, isEmailValid)

Now execute() only does the work if the email address is valid. Super cool!

Note that enabledIf isn't the same as the enabled property. You pass in enabledIf and the action uses that, and its current executing state, to determine if it's currently enabled.

What's really cool is the Button can be bound to the enabled state.

// The button executes the action 
button.setOnClickListener { kaction.execute(input) }

// But the enabled state is dependent on the action's state
kaction.enabled.subscribe { button.isEnabled = it }

Now when the button is pressed, the action is executed. The button's enabled state is bound to the action's enabled property. That means you can feed your form-validation logic into the action as a signal, and your button's enabled state is handled for you. Also, the user can't press the button again before the action is done executing, since it only handles one thing at a time. Cool.

Don't forget to check the sample

Download

Add the dependency to your gradle file:

implementation 'com.tonsser:kaction:0.0.2'

Special Thanks

Once again to the guys at RxSwiftCommunity/Action for the inspiration!

Author

Joaquim Ley, Android Engineer @ Tonsser

• joaquimley
• @joaquimley

License

The MIT License

Copyright (c) 2018 Tonsser

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