Detect when image not found using Compose Coil

Question

I am populating my images using coil in jetpack compose and the issue I face is that I am not able to programmatically identify if the url is no longer valid.

val imageUrl = "www.someinvalidurl.com"
val painter = rememberImagePainter(
    data = imageUrl
)

Image(
    painter = painter
)

The url was previously valid but is not valid anymore. Coil shows the default placeholder url but then I want to identify this failure and attempt to get an image from a different url. I have tried this,

if (painter.state is ImagePainter.State.Error) {
    //failed so try to get an image from a different url
}

But the problem with this is that this block is called even for valid urls.

I am using the following version of coil :

implementation("io.coil-kt:coil-compose:1.4.0")

Is there a different right way of identifying invalid URLs in coil while using jetpack compose

Answer 1

Add a listener that checks for exceptions. In this sample, the file extension should be "jpg" but I removed the "g" to test that the image does not exist:

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

        startActivity(intent)

        setContent {
            val imageUrl = "https://upload.wikimedia.org/wikipedia/commons/thumb/3/3a/Cat03.jpg/1200px-Cat03.jp"
            val painter = rememberImagePainter(
                data = imageUrl,
                builder = {
                    this.listener(
                        onError = {request, ex ->
                            if ((ex as HttpException).response.code() == 400) {
                                // Image not found
                            }
                        }
                    )
                }
            )

            Image(
                painter = painter,
                contentDescription = null
            )
        }
    }
}