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database-ktx: add callbackFlow for eventlisteners (firebase#4012)
* add callbackFlow for RTDB's ValueEventListener * add callbackFlow for RTDB's ChildEventListener * delegate trySendBlocking to DefaultRunLoop * add group to ktx.gradle * update api.txt file
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‎firebase-database/ktx/api.txt‎

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// Signature format: 2.0
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package com.google.firebase.database.ktx {
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public abstract sealed class ChildEvent {
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}
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public static final class ChildEvent.Added extends com.google.firebase.database.ktx.ChildEvent {
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ctor public ChildEvent.Added(@NonNull com.google.firebase.database.DataSnapshot snapshot, @Nullable String previousChildName);
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method @NonNull public com.google.firebase.database.DataSnapshot component1();
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method @Nullable public String component2();
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method @NonNull public com.google.firebase.database.ktx.ChildEvent.Added copy(@NonNull com.google.firebase.database.DataSnapshot snapshot, @Nullable String previousChildName);
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method @Nullable public String getPreviousChildName();
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method @NonNull public com.google.firebase.database.DataSnapshot getSnapshot();
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property @Nullable public final String previousChildName;
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property @NonNull public final com.google.firebase.database.DataSnapshot snapshot;
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}
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public static final class ChildEvent.Changed extends com.google.firebase.database.ktx.ChildEvent {
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ctor public ChildEvent.Changed(@NonNull com.google.firebase.database.DataSnapshot snapshot, @Nullable String previousChildName);
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method @NonNull public com.google.firebase.database.DataSnapshot component1();
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method @Nullable public String component2();
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method @NonNull public com.google.firebase.database.ktx.ChildEvent.Changed copy(@NonNull com.google.firebase.database.DataSnapshot snapshot, @Nullable String previousChildName);
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method @Nullable public String getPreviousChildName();
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method @NonNull public com.google.firebase.database.DataSnapshot getSnapshot();
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property @Nullable public final String previousChildName;
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property @NonNull public final com.google.firebase.database.DataSnapshot snapshot;
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}
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public static final class ChildEvent.Moved extends com.google.firebase.database.ktx.ChildEvent {
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ctor public ChildEvent.Moved(@NonNull com.google.firebase.database.DataSnapshot snapshot, @Nullable String previousChildName);
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method @NonNull public com.google.firebase.database.DataSnapshot component1();
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method @Nullable public String component2();
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method @NonNull public com.google.firebase.database.ktx.ChildEvent.Moved copy(@NonNull com.google.firebase.database.DataSnapshot snapshot, @Nullable String previousChildName);
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method @Nullable public String getPreviousChildName();
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method @NonNull public com.google.firebase.database.DataSnapshot getSnapshot();
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property @Nullable public final String previousChildName;
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property @NonNull public final com.google.firebase.database.DataSnapshot snapshot;
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}
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public static final class ChildEvent.Removed extends com.google.firebase.database.ktx.ChildEvent {
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ctor public ChildEvent.Removed(@NonNull com.google.firebase.database.DataSnapshot snapshot);
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method @NonNull public com.google.firebase.database.DataSnapshot component1();
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method @NonNull public com.google.firebase.database.ktx.ChildEvent.Removed copy(@NonNull com.google.firebase.database.DataSnapshot snapshot);
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method @NonNull public com.google.firebase.database.DataSnapshot getSnapshot();
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property @NonNull public final com.google.firebase.database.DataSnapshot snapshot;
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}
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public final class DatabaseKt {
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method @NonNull public static com.google.firebase.database.FirebaseDatabase database(@NonNull com.google.firebase.ktx.Firebase, @NonNull String url);
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method @NonNull public static com.google.firebase.database.FirebaseDatabase database(@NonNull com.google.firebase.ktx.Firebase, @NonNull com.google.firebase.FirebaseApp app);
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method @NonNull public static com.google.firebase.database.FirebaseDatabase database(@NonNull com.google.firebase.ktx.Firebase, @NonNull com.google.firebase.FirebaseApp app, @NonNull String url);
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method @NonNull public static kotlinx.coroutines.flow.Flow<com.google.firebase.database.ktx.ChildEvent> getChildEvents(@NonNull com.google.firebase.database.Query);
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method @NonNull public static com.google.firebase.database.FirebaseDatabase getDatabase(@NonNull com.google.firebase.ktx.Firebase);
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method @NonNull public static kotlinx.coroutines.flow.Flow<com.google.firebase.database.DataSnapshot> getSnapshots(@NonNull com.google.firebase.database.Query);
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method public static inline <reified T> T getValue(@NonNull com.google.firebase.database.DataSnapshot);
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method public static inline <reified T> T getValue(@NonNull com.google.firebase.database.MutableData);
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}

‎firebase-database/ktx/ktx.gradle‎

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id 'kotlin-android'
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}
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group = "com.google.firebase"
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firebaseLibrary {
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releaseWith project(':firebase-database')
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publishJavadoc = true
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implementation project(':firebase-database')
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implementation 'androidx.annotation:annotation:1.1.0'
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implementation 'com.google.android.gms:play-services-tasks:18.0.1'
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implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:$coroutinesVersion"
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androidTestImplementation 'junit:junit:4.12'
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androidTestImplementation "com.google.truth:truth:$googleTruthVersion"

‎firebase-database/ktx/src/main/kotlin/com/google/firebase/database/ktx/ChildEvent.kt‎

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package com.google.firebase.database.ktx
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import com.google.firebase.database.DataSnapshot
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/**
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* Used to emit events about changes in the child locations of a given
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* [Query] when using the [childEvents] Flow.
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*/
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sealed class ChildEvent {
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/**
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* Emitted when a new child is added to the location.
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*
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* @param snapshot An immutable snapshot of the data at the new child location
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* @param previousChildName The key name of sibling location ordered before the new child. This
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* will be null for the first child node of a location.
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*/
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data class Added(val snapshot: DataSnapshot, val previousChildName: String?) : ChildEvent()
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/**
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* Emitted when the data at a child location has changed.
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*
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* @param snapshot An immutable snapshot of the data at the new data at the child location
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* @param previousChildName The key name of sibling location ordered before the child. This will
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* be null for the first child node of a location.
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*/
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data class Changed(val snapshot: DataSnapshot, val previousChildName: String?) : ChildEvent()
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/**
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* Emitted when a child is removed from the location.
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*
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* @param snapshot An immutable snapshot of the data at the child that was removed.
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*/
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data class Removed(val snapshot: DataSnapshot) : ChildEvent()
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/**
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* Emitted when a child location's priority changes.
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*
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* @param snapshot An immutable snapshot of the data at the location that moved.
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* @param previousChildName The key name of the sibling location ordered before the child
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* location. This will be null if this location is ordered first.
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*/
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data class Moved(val snapshot: DataSnapshot, val previousChildName: String?) : ChildEvent()
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}

‎firebase-database/ktx/src/main/kotlin/com/google/firebase/database/ktx/Database.kt‎

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import com.google.firebase.FirebaseApp
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import com.google.firebase.components.Component
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import com.google.firebase.components.ComponentRegistrar
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import com.google.firebase.database.ChildEventListener
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import com.google.firebase.database.DataSnapshot
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import com.google.firebase.database.DatabaseError
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import com.google.firebase.database.FirebaseDatabase
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import com.google.firebase.database.GenericTypeIndicator
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import com.google.firebase.database.MutableData
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import com.google.firebase.database.Query
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import com.google.firebase.database.ValueEventListener
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import com.google.firebase.ktx.Firebase
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import com.google.firebase.platforminfo.LibraryVersionComponent
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import kotlinx.coroutines.cancel
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import kotlinx.coroutines.channels.awaitClose
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import kotlinx.coroutines.channels.trySendBlocking
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import kotlinx.coroutines.flow.callbackFlow
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/** Returns the [FirebaseDatabase] instance of the default [FirebaseApp]. */
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val Firebase.database: FirebaseDatabase
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return getValue(object : GenericTypeIndicator<T>() {})
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}
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/**
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* Starts listening to this query and emits its values via a [Flow].
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*
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* - When the returned flow starts being collected, a [ValueEventListener] will be attached.
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* - When the flow completes, the listener will be removed.
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*/
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val Query.snapshots
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get() = callbackFlow<DataSnapshot> {
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val listener = addValueEventListener(object : ValueEventListener {
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override fun onDataChange(snapshot: DataSnapshot) {
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repo.scheduleNow {
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trySendBlocking(snapshot)
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}
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}
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override fun onCancelled(error: DatabaseError) {
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cancel(message = "Error getting Query snapshot", cause = error.toException())
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}
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})
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awaitClose { removeEventListener(listener) }
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}
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/**
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* Starts listening to this query's child events and emits its values via a [Flow].
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*
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* - When the returned flow starts being collected, a [ChildEventListener] will be attached.
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* - When the flow completes, the listener will be removed.
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*/
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val Query.childEvents
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get() = callbackFlow<ChildEvent> {
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val listener = addChildEventListener(object : ChildEventListener {
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override fun onChildAdded(snapshot: DataSnapshot, previousChildName: String?) {
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repo.scheduleNow {
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trySendBlocking(ChildEvent.Added(snapshot, previousChildName))
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}
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}
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override fun onChildChanged(snapshot: DataSnapshot, previousChildName: String?) {
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repo.scheduleNow {
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trySendBlocking(ChildEvent.Changed(snapshot, previousChildName))
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}
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}
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override fun onChildRemoved(snapshot: DataSnapshot) {
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repo.scheduleNow {
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trySendBlocking(ChildEvent.Removed(snapshot))
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}
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}
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override fun onChildMoved(snapshot: DataSnapshot, previousChildName: String?) {
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repo.scheduleNow {
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trySendBlocking(ChildEvent.Moved(snapshot, previousChildName))
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}
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}
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override fun onCancelled(error: DatabaseError) {
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cancel(message = "Error getting Query childEvent", cause = error.toException())
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}
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})
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awaitClose { removeEventListener(listener) }
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}
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internal const val LIBRARY_NAME: String = "fire-db-ktx"
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/** @suppress */

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