``` val resp = webservicesAPI fetchLatest resp let repositor kotlinlang #getting-started

val resp = webservicesAPI.fetchLatest()
        resp?.let {
            repository.name = resp.name   
            repository.lastUpdate = resp.lastUpdate   
        }

diesieben07

08/10/2020, 2:07 PM

The

let

lambda takes a param:

fetchlatest()?.let { resp -> 
    repository.lastUpdate = resp.lastUpdate
    // etc
}

Daniele B

08/10/2020, 2:08 PM

@diesieben07 thanks! what about if there are 2 lines in the let block, as I just amended ?

diesieben07

08/10/2020, 2:09 PM

You can as many lines in the let block as you want, hence why I put "etc" there 😉

👍 1

Daniele B

08/10/2020, 2:09 PM

ok, I see! thanks!

marstran

08/10/2020, 2:21 PM

This might be just stylistic, but I think

apply

is better here:

webservicesAPI.fetchLatest()
  ?.apply {
      repository.name = name   
      repository.lastUpdate = lastUpdate   
  }

✔️ 3

🙅‍♀️🏻 1

Daniele B

08/10/2020, 2:25 PM

@marstran thanks! so is

.apply

running only if

fetchLatest()

returns not null ?

marstran

08/10/2020, 2:26 PM

Ah, didn't see the

. You still need that. I fixed the code.

Daniele B

08/10/2020, 2:26 PM

ok, I see, thanks!

diesieben07

08/10/2020, 2:26 PM

No,

apply

is like

let

, except that it uses a lambda wiht receiver instead of a lambda with parameter.

marstran

08/10/2020, 2:27 PM

Yes, and it returns the input rather than the return value of the lambda.

Daniele B

08/10/2020, 2:27 PM

if (remoteData.lastUpdate == null) {
    fetchWeeklyCasesList()
}

do you also have a suggestion to simplify this code?

diesieben07

08/10/2020, 2:27 PM

Not sure what you want to simplify about an if statement 🙂 I would say that code is perfectly fine the way it is.

Daniele B

08/10/2020, 2:28 PM

maybe writing

instead of

null

or maybe it can stay like this 🙂

marstran

08/10/2020, 2:29 PM

Yes, I think it should stay. The intention is clearer with the explicit null-check.

👍 1

Joost Klitsie

08/11/2020, 6:45 AM

Also you can think about creating a mapper, This is a great article on the why and mapping from dto's to domain objects is highly recommended, as, in short, it will make your code better testable. In that case your code could be in the likes of:

val repository = webservicesAPI.fetchLatest()?.let { mapper.map(it) }

So I highly recommend reading this: https://proandroiddev.com/the-real-repository-pattern-in-android-efba8662b754

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