Add BoxStore.awaitCallInTx suspend function.

Author: greenrobot-team

objectbox-kotlin/src/main/kotlin/io/objectbox/kotlin/BoxStore.kt

@@ -18,6 +18,10 @@ package io.objectbox.kotlin
 
 import io.objectbox.Box
 import io.objectbox.BoxStore
+import java.util.concurrent.Callable
+import kotlin.coroutines.resume
+import kotlin.coroutines.resumeWithException
+import kotlin.coroutines.suspendCoroutine
 import kotlin.reflect.KClass
 
 
@@ -27,3 +31,23 @@ inline fun <reified T> BoxStore.boxFor(): Box<T> = boxFor(T::class.java)
 /** Shortcut for `BoxStore.boxFor(Entity::class.java)`. */
 @Suppress("NOTHING_TO_INLINE")
 inline fun <T : Any> BoxStore.boxFor(clazz: KClass<T>): Box<T> = boxFor(clazz.java)
+
+/**
+ * Wraps [BoxStore.callInTxAsync] in a coroutine that suspends until the transaction has completed.
+ * Likewise, on success the return value of the given [callable] is returned, on failure an exception is thrown.
+ *
+ * Note that even if the coroutine is cancelled the callable is always executed.
+ *
+ * The callable (and transaction) is submitted to the ObjectBox internal thread pool.
+ */
+suspend fun <V : Any> BoxStore.awaitCallInTx(callable: Callable<V?>): V? {
+    return suspendCoroutine { continuation ->
+        callInTxAsync(callable) { result, error ->
+            if (error != null) {
+                continuation.resumeWithException(error)
+            } else {
+                continuation.resume(result)
+            }
+        }
+    }
+}

tests/objectbox-java-test/build.gradle

@@ -54,6 +54,8 @@ dependencies {
     }
 
     testImplementation "junit:junit:$junit_version"
+    // To test Coroutines
+    testImplementation("org.jetbrains.kotlinx:kotlinx-coroutines-test:$coroutines_version")
     // To test Kotlin Flow
     testImplementation 'app.cash.turbine:turbine:0.5.2'
 }

tests/objectbox-java-test/src/test/java/io/objectbox/BoxStoreTestK.kt

@@ -1,11 +1,14 @@
 package io.objectbox
 
+import io.objectbox.kotlin.awaitCallInTx
 import io.objectbox.kotlin.boxFor
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.test.runTest
 import org.junit.Assert.assertEquals
 import org.junit.Test
 
 
-class BoxStoreTestK: AbstractObjectBoxTest() {
+class BoxStoreTestK : AbstractObjectBoxTest() {
 
     /**
      * This is mostly to test the expected syntax works without errors or warnings.
@@ -20,4 +23,23 @@ class BoxStoreTestK: AbstractObjectBoxTest() {
         val box2 = store.boxFor(TestEntity::class)
         assertEquals(boxJavaApi, box2)
     }
+
+    @ExperimentalCoroutinesApi
+    @Test
+    fun awaitCallInTx() {
+        val box = store.boxFor<TestEntity>()
+        runTest {
+            // put
+            val id = store.awaitCallInTx {
+                box.put(createTestEntity("Hello", 1))
+            }
+            assertEquals(1, id!!)
+
+            // get
+            val note = store.awaitCallInTx {
+                box.get(id)
+            }
+            assertEquals("Hello", note!!.simpleString)
+        }
+    }
 }