I am trying to use Room with compose and kotlin. I...

# compose

[amar_1995]

I am trying to use Room with compose and kotlin.
I know there is compability issue with kapt and compose and so that it throws backend IR error.
But now in build gradle file i removed below line and it worked.

buildFeatures {
        compose true
}

Now even removing this line I am able to call compose function and load ui.
So, what does this line means and its purpose.

[Mark Murphy]

IIRC, I believe that you will find that you cannot recompose your UI. It renders initially, but changes in the states of models and stuff will not cause the UI to change.

[sindrenm]

I believe what Mark says is correct. Keep in mind that it should be possible to put your Room (or rather, kapt-dependent) code in a module that does not enable Compose, but enables kapt, and your Compose code in a different module that depends on that module.

Per this comment on the YouTrack issue:

https://youtrack.jetbrains.com/issue/KT-34583#focus=streamItem-27-3901882.0-0

I haven't tried this myself, but it sounds likely to work.

[Ian Warwick]

I managed to use Room in my playground app by putting room in a different module, it seems to work in this respect https://github.com/fluxtah/memset

[sindrenm]

Nice. 👍

[amar_1995]

@Mark Murphy I wrote this piece of code in mainActivity.

MaterialTheme {
    val value = +state { 0 }
    Column {
        Greeting(value.value.toString())
        Button(text = "Click", onClick = {
            value.value += 1
        })
    }
}

And on every click value is changing

[Mark Murphy]

try moving that logic into a @Composable function and see what happens (or is it in a @Composable function already?)

[amar_1995]

It is already in setContent

[Mark Murphy]

no, I mean pulling it out into a separate function:

MaterialTheme {
  renderGoodStuff()
}

@Composable
fun renderGoodStuff() {
    val value = +state { 0 }
    Column {
        Greeting(value.value.toString())
        Button(text = "Click", onClick = {
            value.value += 1
        })
    }
}

[amar_1995]

Yeah, write now I tried this also and it is working

[amar_1995]

setContent {
            MaterialTheme {
                TestBind()
//                val value = +state { 0 }
//                Column {
//                    Greeting(value.value.toString())
//                    Button(text = "Click", onClick = {
//                        value.value += 1
//                    })
//                }
            }
        }

[amar_1995]

@Composable
fun TestBind() {
    val value = +state { 0 }
    Column {
        Greeting(value.value.toString())
        Button(text = "Click", onClick = {
            value.value += 1
        })
    }
}

[Mark Murphy]

🤷 OK, then I guess I do not know what that buildFeatures is enabling -- sorry!

[Manuel Wrage]

Your example works because on every change the whole tree will be recomposed. You will notice heavy performance issues if you keep the compiler disabled.

It's also not possible to conditionally call composables without the compiler.

[amar_1995]

@Manuel Wrage Yes, you are right. I got this error java.lang.IllegalStateException: Expected a group start when disabled the compose feature.

[amar_1995]

@Ian Warwick First thanks for suggestion to keep in separate module.
Can you please tell me if I want to add retrofit api network call and models where should I add it.
I think adding it in data module will be good. Because I want to use same entities class for gson parser also.

[sindrenm]

Yeah, depends on how much you wanna modularize, too. Ground rule (for now, while they're working on fixing the incompatibility), as long as you don't have kapt and Compose enabled in the same module, you should be good. In a larger project, I'd probably try to make sure JSON models (e.g. Moshi or kotlinx.serialization or whatnot) aren't exposed out of any kind of repository layer, and so to keep them in their own module would make some sense to me. But if you wanna modularize by feature more, then you'd maybe have repositories as part of a feature (a UserRepository in the users module, for instance), so … I guess it just depends on preference. 😛

[Ian Warwick]

@amar_1995 personally I would add them in a separate module, if you want to use the same model you could put that model also in its own module so it can be shared with data and maybe :net module but again this is personal, @sindrenm makes some great points about modularisation, at my company we tend to modularise by feature so often we have an api counterpart such as feature-search could have a search-api when we want to share its API functionality with other feature modules

[Klaas Kabini]

Mark is right. I had an issue before where the UI did not recompose on state change just to find out that i missed enabling compose under buildFeatures.