Adding Modifiers Conditionally in Jetpack Compose

While using Jetpack Compose, you may have run into an instance where you needed to add a modifier only if a certain condition was true. You may have used a solution similar to this one:

Modifier.then(
    if (clickable) Modifier.clickable(onClick) else Modifier,
)

This is certainly a valid way of adding a modifier conditionally, but it’s not particularly concise. To make the task at hand easier, you can instead create a helper modifier for conditional modification, which is possible because modifiers are defined as extension functions.

inline fun Modifier.thenIf(
    condition: Boolean,
    crossinline other: Modifier.() -> Modifier,
) = if (condition) other() else this

This modifier can be used as follows.

Modifier.thenIf(clickable) { clickable(onClick) }

If you need to add multiple modifiers, remember to chain them:

Modifier.thenIf(clickable) {
    clickable(onClick).color(Color.Blue)
}

Besides adding a modifier under a certain condition, you may need to add a modifier if a value is not null. In such a case, you’ll typically also want to use the not-null value in the modifier. In order to avoid using not-null assertion, you can once again create a helper modifier:

inline fun <T> Modifier.thenIfNotNull(
    value: T?,
    crossinline other: Modifier.(T) -> Modifier,
) = if (value != null) other(value) else this

This modifier can be used as follows.

Modifier.thenIfNotNull(onClick) { clickable(it) }