Type 'State?>' has no method 'getValue(Nothing?, KProperty<*>)' and thus it cannot serve as a delegate

Question

I\'m trying to get a value from LiveData with observeAsState in jetpack compose, but I get a weird error

Type \'State\' has no method \'getValue

Answer 1

To fix the error add the following imports:

// for a 'val' variable
import androidx.compose.runtime.getValue

// for a `var` variable also add
import androidx.compose.runtime.setValue

// or just
import androidx.compose.runtime.*

To use a variable as a property delegate you should provide getValue operator function for read-only val variables and getValue and setValue functions for var variables.

To read more about how property delegates and state are combined in jetpack compose see Use remember to create internal state in a composable documentation section. There's also an explanation in Thinking in Compose video.

Answer 2

If you get a compiler error that observeAsState or getValue are not defined make sure you have the following imports:

import androidx.compose.runtime.getValue

import androidx.compose.runtime.livedata.observeAsState

This information is from Step #4 in the "Using State in Jetpack Compose" codelab.

Answer 3

I think type of items must be nullable since you observing LiveData:

val items: List<User>? by userViewModel.fetchUserList.observeAsState()

Answer 4

In my case, in a compose application it was this missing import that provoc the error

import androidx.compose.getValue