---
title: "ObserverModifierNode"
description: "[Modifier.Node]s that implement ObserverNode can provide their own implementation of
[onObservedReadsChanged] that will be called in response to changes to snapshot objects read
within an [observeReads] block."
type: "interface"
---

<div class='type'>Interface</div>


<a id='references'></a>

<div class='sourceset sourceset-common'>Common</div>



```kotlin
interface ObserverModifierNode : DelegatableNode
```


`Modifier.Node`s that implement ObserverNode can provide their own implementation of
`onObservedReadsChanged` that will be called in response to changes to snapshot objects read
within an `observeReads` block.


## Functions

```kotlin
fun onObservedReadsChanged()
```


This callback is called when any values that are read within the `observeReads` block change.
It is called after the snapshot is committed. `onObservedReadsChanged` is called on the UI
thread, and only called once in response to snapshot observation. To continue observing
further updates, you need to call `observeReads` again.