How to handle retry request?

[fjr619]

with this pattern, it is really easy to use, but i have a problem to retry call API when got error, because we already have livedata in repository and calling api in datasource, how we can get retry request with this pattern?

[mfsi-prateeksharma]

Hi @fjr619
For that, you need to change the approach of initializing the live data in viewmodel from lazy to var or val,
var example: () -> LiveData<Result<SampleResponse>> = { repository.sample(createRequest()) }

[fjr619]

var example: () -> LiveData<Result<SampleResponse>> = { repository.sample(createRequest()) }

with this approach how we trigger that from button in activity or fragment?
i'm new in kotlin can you explain about this part
var example: () -> LiveData<Result<SampleResponse>> what is that ?

[mfsi-prateeksharma]

@fjr619 no problem,

viewModel.example().observe(viewLifecycleOwner, Observer { result ->
            when (result) {
                is Result.Success -> {
                    progressBar.visibility = View.GONE
                    Timber.d("response === %s", result.data.email)
                     }
                is Result.Loading -> {
                    progressBar.visibility = View.VISIBLE
                }
                is Result.Error -> {
                    progressBar.visibility = View.GONE
                }
            }
        })

Let me know if it works for you.

[fjr619]

so i create a function for observe in activity

private fun subscribeUI() {
viewModel.example().observe(viewLifecycleOwner, Observer { result ->
            when (result) {
                is Result.Success -> {
                    progressBar.visibility = View.GONE
                    Timber.d("response === %s", result.data.email)
                     }
                is Result.Loading -> {
                    progressBar.visibility = View.VISIBLE
                }
                is Result.Error -> {
                    progressBar.visibility = View.GONE
                }
            }
        })
}

then in my activity will become

override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

       subscribeUI() //this is for first time request
       btnRetry.setOnClickListener {
           subscribeUI() //this is for retry request
      }
}

is it correct?

[mfsi-prateeksharma]

@fjr619 yes, I assume you have everything initialized and injected as per the project.
In case you still get the issue, you can provide me your sample project at [email protected] or create a private repo

[fjr619]

my other question, i assume with MVVM it will resolve change orientation problem, but when i rotate my phone, it will trigger calling API again, how to solved it? I read that in ViewModel we can use

init {
   callAPI()
}

to solve the problem, it doesn't with LEGO-Catalog example pattern