Add FhirEngine interface method 'withTransaction'

engine/src/main/java/com/google/android/fhir/FhirEngine.kt

@@ -58,54 +58,7 @@ import org.hl7.fhir.r4.model.ResourceType
  * val fhirEngine = FhirEngineProvider.getInstance(this)
  * ```
  */
-interface FhirEngine {
-  /**
-   * Creates one or more FHIR [Resource]s in the local storage. FHIR Engine requires all stored
-   * resources to have a logical [Resource.id]. If the `id` is specified in the resource passed to
-   * [create], the resource created in `FhirEngine` will have the same `id`. If no `id` is
-   * specified, `FhirEngine` will generate a UUID as that resource's `id` and include it in the
-   * returned list of IDs.
-   *
-   * @param resource The FHIR resources to create.
-   * @return A list of logical IDs of the newly created resources.
-   */
-  suspend fun create(vararg resource: Resource): List<String>
-
-  /**
-   * Loads a FHIR resource given its [ResourceType] and logical ID.
-   *
-   * @param type The type of the resource to load.
-   * @param id The logical ID of the resource.
-   * @return The requested FHIR resource.
-   * @throws ResourceNotFoundException if the resource is not found.
-   */
-  @Throws(ResourceNotFoundException::class)
-  suspend fun get(type: ResourceType, id: String): Resource
-
-  /**
-   * Updates one or more FHIR [Resource]s in the local storage.
-   *
-   * @param resource The FHIR resources to update.
-   */
-  suspend fun update(vararg resource: Resource)
-
-  /**
-   * Removes a FHIR resource given its [ResourceType] and logical ID.
-   *
-   * @param type The type of the resource to delete.
-   * @param id The logical ID of the resource.
-   */
-  suspend fun delete(type: ResourceType, id: String)
-
-  /**
-   * Searches the database and returns a list of resources matching the [Search] specifications.
-   *
-   * @param search The search criteria to apply.
-   * @return A list of [SearchResult] objects containing the matching resources and any included
-   *   references.
-   */
-  suspend fun <R : Resource> search(search: Search): List<SearchResult<R>>
-
+interface FhirEngine : CrudFhirEngine {
   /**
    * Synchronizes upload results with the database.
    *
@@ -204,6 +157,71 @@ interface FhirEngine {
   suspend fun purge(type: ResourceType, ids: Set<String>, forcePurge: Boolean = false)
 }
 
+interface CrudFhirEngine {
+  /**
+   * Creates one or more FHIR [Resource]s in the local storage. FHIR Engine requires all stored
+   * resources to have a logical [Resource.id]. If the `id` is specified in the resource passed to
+   * [create], the resource created in `FhirEngine` will have the same `id`. If no `id` is
+   * specified, `FhirEngine` will generate a UUID as that resource's `id` and include it in the
+   * returned list of IDs.
+   *
+   * @param resource The FHIR resources to create.
+   * @return A list of logical IDs of the newly created resources.
+   */
+  suspend fun create(vararg resource: Resource): List<String>
+
+  /**
+   * Loads a FHIR resource given its [ResourceType] and logical ID.
+   *
+   * @param type The type of the resource to load.
+   * @param id The logical ID of the resource.
+   * @return The requested FHIR resource.
+   * @throws ResourceNotFoundException if the resource is not found.
+   */
+  @Throws(ResourceNotFoundException::class)
+  suspend fun get(type: ResourceType, id: String): Resource
+
+  /**
+   * Updates one or more FHIR [Resource]s in the local storage.
+   *
+   * @param resource The FHIR resources to update.
+   */
+  suspend fun update(vararg resource: Resource)
+
+  /**
+   * Removes a FHIR resource given its [ResourceType] and logical ID.
+   *
+   * @param type The type of the resource to delete.
+   * @param id The logical ID of the resource.
+   */
+  suspend fun delete(type: ResourceType, id: String)
+
+  /**
+   * Searches the database and returns a list of resources matching the [Search] specifications.
+   *
+   * Example:
+   * ```
+   * fhirEngine.search<Patient> {
+   *  filter(Patient.GIVEN, {
+   *    value = "Kiran"
+   *    modifier = StringFilterModifier.MATCHES_EXACTLY
+   *  })
+   * }
+   * ```
+   *
+   * @param search The search criteria to apply.
+   * @return A list of [SearchResult] objects containing the matching resources and any included
+   *   references.
+   */
+  suspend fun <R : Resource> search(search: Search): List<SearchResult<R>>
+
+  /**
+   * Adds support for performing actions on `FhirEngine` as a single atomic transaction where the
+   * entire set of changes succeed or fail as a single entity
+   */
+  suspend fun withTransaction(block: suspend CrudFhirEngine.() -> Unit)
+}
+
 /**
  * Retrieves a FHIR resource of type [R] with the given [id] from the local storage.
  *

engine/src/main/java/com/google/android/fhir/impl/FhirEngineImpl.kt

@@ -17,6 +17,7 @@
 package com.google.android.fhir.impl
 
 import android.content.Context
+import com.google.android.fhir.CrudFhirEngine
 import com.google.android.fhir.FhirEngine
 import com.google.android.fhir.FhirEngineProvider
 import com.google.android.fhir.LocalChange
@@ -106,6 +107,10 @@ internal class FhirEngineImpl(private val database: Database, private val contex
     }
   }
 
+  override suspend fun withTransaction(block: suspend CrudFhirEngine.() -> Unit) {
+    database.withTransaction { block.invoke(this@FhirEngineImpl) }
+  }
+
   private suspend fun saveResolvedResourcesToDatabase(resolved: List<Resource>?) {
     resolved?.let {
       database.deleteUpdates(it)

engine/src/main/java/com/google/android/fhir/testing/Utilities.kt

@@ -20,6 +20,7 @@ import androidx.work.Data
 import ca.uhn.fhir.context.FhirContext
 import ca.uhn.fhir.context.FhirVersionEnum
 import ca.uhn.fhir.parser.IParser
+import com.google.android.fhir.CrudFhirEngine
 import com.google.android.fhir.FhirEngine
 import com.google.android.fhir.LocalChange
 import com.google.android.fhir.LocalChangeToken
@@ -176,6 +177,8 @@ internal object TestFhirEngineImpl : FhirEngine {
     download().collect()
   }
 
+  override suspend fun withTransaction(block: suspend CrudFhirEngine.() -> Unit) {}
+
   override suspend fun count(search: Search): Long {
     return 0
   }

engine/src/test/java/com/google/android/fhir/impl/FhirEngineImplTest.kt

@@ -22,6 +22,7 @@ import com.google.android.fhir.FhirServices.Companion.builder
 import com.google.android.fhir.LocalChange
 import com.google.android.fhir.LocalChange.Type
 import com.google.android.fhir.db.ResourceNotFoundException
+import com.google.android.fhir.delete
 import com.google.android.fhir.get
 import com.google.android.fhir.lastUpdated
 import com.google.android.fhir.logicalId
@@ -783,6 +784,87 @@ class FhirEngineImplTest {
     assertThat(services.database.getLocalChangesCount()).isEqualTo(0)
   }
 
+  @Test
+  fun `withTransaction saves all changes successfully in order`() = runTest {
+    val patient01ID = "patient-01"
+    val patient01 =
+      Patient().apply {
+        id = patient01ID
+        gender = Enumerations.AdministrativeGender.FEMALE
+      }
+    val patient02ID = "patient-02"
+    val patient02 =
+      Patient().apply {
+        id = patient02ID
+        gender = Enumerations.AdministrativeGender.MALE
+      }
+    val patient03ID = "patient-03"
+    val patient03 =
+      Patient().apply {
+        id = patient03ID
+        gender = Enumerations.AdministrativeGender.FEMALE
+      }
+
+    fhirEngine.create(patient01)
+    assertThat(fhirEngine.get<Patient>(patient01ID).gender)
+      .isEqualTo(Enumerations.AdministrativeGender.FEMALE)
+    fhirEngine.withTransaction {
+      fhirEngine.create(patient02, patient03)
+      patient01.gender = Enumerations.AdministrativeGender.FEMALE
+      fhirEngine.update(patient01)
+      fhirEngine.delete<Patient>(patient01ID)
+    }
+    assertResourceEquals(patient02, fhirEngine.get<Patient>(patient02ID))
+    assertResourceEquals(patient03, fhirEngine.get<Patient>(patient03ID))
+    assertThrows(ResourceNotFoundException::class.java) {
+      runBlocking { fhirEngine.get<Patient>(patient01ID) }
+    }
+  }
+
+  @Test
+  fun `withTransaction reverts all changes when an error occurs`() = runTest {
+    val patient01ID = "patient-01"
+    val patient01 =
+      Patient().apply {
+        id = patient01ID
+        gender = Enumerations.AdministrativeGender.FEMALE
+      }
+    val patient02ID = "patient-02"
+    val patient02 =
+      Patient().apply {
+        id = patient02ID
+        gender = Enumerations.AdministrativeGender.MALE
+      }
+    val patient03ID = "patient-03"
+    val patient03 =
+      Patient().apply {
+        id = patient03ID
+        gender = Enumerations.AdministrativeGender.FEMALE
+      }
+    val patient03Updated =
+      patient03.copy().apply { gender = Enumerations.AdministrativeGender.MALE }
+
+    fhirEngine.create(patient03)
+    try {
+      fhirEngine.withTransaction {
+        this.create(patient01)
+        this.create(patient02)
+        this.update(patient03Updated)
+        this.get(ResourceType.Patient, "non_existent_patient_id")
+          as Patient // Force ResourceNotFoundException
+      }
+    } catch (_: ResourceNotFoundException) {}
+
+    assertThrows(ResourceNotFoundException::class.java) {
+      runBlocking { fhirEngine.get<Patient>(patient01ID) }
+    }
+    assertThrows(ResourceNotFoundException::class.java) {
+      runBlocking { fhirEngine.get<Patient>(patient02ID) }
+    }
+    assertResourceEquals(patient03, fhirEngine.get<Patient>(patient03ID))
+    assertResourceNotEquals(patient03Updated, fhirEngine.get<Patient>(patient03ID))
+  }
+
   companion object {
     private const val TEST_PATIENT_1_ID = "test_patient_1"
     private var TEST_PATIENT_1 =