How to show a toast msg on coroutine in composable fun?

First of all, My english is bad. sorry about that

I wanna show a toast msg like below

but it not working.

'this' should be context but it always CoroutineScope

LocalContext.current not also working

is it bad practice? if yes plz explain and give me good answer!

@Composable
fun DogButton() {

    androidx.compose.material.Button(onClick = {

        CoroutineScope(Dispatchers.Main).launch {

            try {

                val response = ApiAdapter.apiClient.getRandomDogImage()

                if (response.isSuccessful && response.body() != null) {

                } else {

                    Toast.makeText(this, "Error", Toast.LENGTH_SHORT) // it occur compile error. 


                }

            } catch (exception : Exception) {


            }
        }

    /*TODO*/ }) {

        Text(text = "Get a Dog Image")
    }
}

I hope it will be good

You can't get the LocalContext from your coroutine, since a coroutine launch block is not a Composable. Use it before declaring your Button, and get the application Context to be safe, since you're using the context in a coroutine that might outlive the composable.

@Composable
fun DogButton() {
    val appContext = LocalContext.applicationContext

    androidx.compose.material.Button(onClick = {
        //...
        Toast.makeText(appContext, ...

It is probably more appropriate to do this kind of work in a ViewModel or other similar class for code-organization purposes. You could use an AndroidViewModel and use its Application reference to get a Context. Then this click listener only needs to call the ViewModel function.

This code:

CoroutineScope(Dispatchers.Main).launch {

is usually an antipattern, regardless of whether you're in a Composable. It means you are creating an unconfined coroutine--it will live until completion regardless of whether the associated part of your app is already gone and destroyed, and therefore it is a source of memory leaks and other wasted resources.

Usually, you always start a coroutine using an appropriate CoroutineScope that has a an appropriate lifetime. One that will be cancelled when the work you're launching from it is obsolete.

Possibly, your code is an exception because it isn't interacting with the composable or Activity UI at all. It only launches a Toast, which is a UI at the scope of the application. So if you really want to show this Toast even if the Activity is closed, then it would be OK to launch your coroutine this way.

It is my opinion that in this case, you should use GlobalScope to clearly indicate that this is a coroutine that is not part of a lifecycle that might cancel it. It is effectively the same but you won't be creating a redundant CoroutineScope.

Composable functions should not be used to call APIs or do any processing intensive work. (Source) Your requirement of calling an API and showing a Toast on failure can be handled inside a ViewModel and the respective onClick of that button.