CODEWITHSUNDEEP
androidmvpandroid-mvvmandroid-mvp
matip
matip

Reputation: 890

Does every view have to have presenter in MVP pattern?

I am working on a small application using MVP pattern. My home activity has viewpager with multiple fragments in it and each fragment has its own presenter. Fragments aren't communicating with each other so the activity doesn't have any logic, it is just initializing fragments on start. So if I would like to implement the pattern by the book and stay true to its principals should I implement presenter also for the activity? And if so what should be its role?

Upvotes: 0

Views: 1203

Answers (2)

Costa
Costa

Reputation: 492

For using the fragments with their own presenters, I try to use the presenter-contract classes duo to manage the UI events in the fragments.

For example, Consider a click event to show a toast message in case of two possible outcomes: 1. Save and 2. Delete

Then, I will declare two view contract methods like this:

interface View{
     fun showSaveMessage()
     fun showDeleteMessage()
}

And then, in the fragment, I will use an instance of my presenter class to display the messages at appropriate times like: presenter.doSaveAction(), the presenter in turn will cause the view to show the toast message.

Also, when I come to the actual logic of the fragment, like for fetching some data from a remote server, I use Interactor class along with the Presenter-View classes to perform it.

I believe staying true to all the principles is virtually dependent on what kind of application you are building. Sometimes, it is more feasible to use MVVM with MVP than only MVP pattern for the app architecture too.

I hope this answers your question, kind of?

Upvotes: 0

Luis Alonso Paulino Flores
Luis Alonso Paulino Flores

Reputation: 590

If you want to implement MVP by the book and stay true to its principals, every UI that has user interaction should have a presenter. In this case, if your activity is not interacting with the user, there is no need to have a presenter, and your fragments can have their own. If your activity needs, let's say show a loading to the user because of some data loading prior to show the fragments (this is a user interaction because you are interacting with the user to let them know that something is happening so they should wait), then might be good to consider having a presenter for the activity.

MVP doesn't care at all about whether is an Activity/Fragment/View, it just knows View which is considered as an abstraction of whatever can be shown to the user :)

That is at least, from the 'rules' perspective. My 2 cents is, be flexible, if you see that it actually ends up adding value to you and your project, do it, otherwise, sometimes you have to 'break' the rules or create your own.

Upvotes: 2

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