Adding Modifiers Conditionally in Jetpack Compose

Simplifying conditional modification with extension functions.

April 24, 2022

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 itʼs 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 declared 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, youʼll 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) }

© 2018–2022 Patryk Michalik

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