Overload FhirEngine.get() to Allow Fetching Multiple Resources by their IDs

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

@@ -83,6 +83,17 @@ interface FhirEngine {
   @Throws(ResourceNotFoundException::class)
   suspend fun get(type: ResourceType, id: String): Resource
 
+  /**
+   * Loads multiple FHIR resources given [ResourceType] and logical IDs.
+   *
+   * @param type The type of the resource to load.
+   * @param ids The logical IDs of the resources.
+   * @return The list of requested FHIR resources.
+   * @throws ResourceNotFoundException if the resources are not found.
+   */
+  @Throws(ResourceNotFoundException::class)
+  suspend fun get(type: ResourceType, vararg ids: String): List<Resource>
+
   /**
    * Updates one or more FHIR [Resource]s in the local storage.
    *
@@ -227,6 +238,19 @@ suspend inline fun <reified R : Resource> FhirEngine.get(id: String): R {
   return get(getResourceType(R::class.java), id) as R
 }
 
+/**
+ * Retrieves FHIR resources of type [R] with the given [ids] from the local storage.
+ *
+ * @param R The type of the FHIR resource to retrieve.
+ * @param ids The logical IDs of the resources to retrieve.
+ * @return The list of requested FHIR resources.
+ * @throws ResourceNotFoundException if the resource is not found.
+ */
+@Throws(ResourceNotFoundException::class)
+suspend inline fun <reified R : Resource> FhirEngine.get(vararg ids: String): List<R> {
+  return get(getResourceType(R::class.java), *ids).map { it as R }
+}
+
 /**
  * Deletes a FHIR resource of type [R] with the given [id] from the local storage.
  *

engine/src/main/java/com/google/android/fhir/db/Database.kt

@@ -84,6 +84,15 @@ internal interface Database {
   @Throws(ResourceNotFoundException::class)
   suspend fun select(type: ResourceType, id: String): Resource
 
+  /**
+   * Selects the FHIR resources of type `clazz` with `ids`.
+   *
+   * @param <R> The resource type
+   * @throws ResourceNotFoundException if the resources are not found in the database
+   */
+  @Throws(ResourceNotFoundException::class)
+  suspend fun selectResources(type: ResourceType, vararg ids: String): List<Resource>
+
   /**
    * Selects the saved `ResourceEntity` of type `clazz` with `id`.
    *

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

@@ -206,6 +206,14 @@ internal class DatabaseImpl(
       ?: throw ResourceNotFoundException(type.name, id)
   }
 
+  override suspend fun selectResources(type: ResourceType, vararg ids: String): List<Resource> {
+    val resources =
+      resourceDao.getResources(resourceIds = ids, resourceType = type)
+        ?: throw ResourceNotFoundException(type.name, ids.joinToString(","))
+
+    return resources.map { iParser.parseResource(it) as Resource }
+  }
+
   override suspend fun insertSyncedResources(resources: List<Resource>) {
     db.withTransaction { insertRemote(*resources.toTypedArray()) }
   }

engine/src/main/java/com/google/android/fhir/db/impl/dao/ResourceDao.kt

@@ -200,6 +200,17 @@ internal abstract class ResourceDao {
   )
   abstract suspend fun getResource(resourceId: String, resourceType: ResourceType): String?
 
+  @Query(
+    """
+        SELECT serializedResource
+        FROM ResourceEntity
+        WHERE resourceId IN (:resourceIds) AND resourceType = :resourceType""",
+  )
+  abstract suspend fun getResources(
+    vararg resourceIds: String,
+    resourceType: ResourceType,
+  ): List<String>?
+
   @Query(
     """
         SELECT *

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

@@ -52,6 +52,9 @@ internal class FhirEngineImpl(private val database: Database, private val contex
   override suspend fun get(type: ResourceType, id: String) =
     withContext(Dispatchers.IO) { database.select(type, id) }
 
+  override suspend fun get(type: ResourceType, vararg ids: String) =
+    withContext(Dispatchers.IO) { database.selectResources(type, *ids) }
+
   override suspend fun update(vararg resource: Resource) =
     withContext(Dispatchers.IO) { database.update(*resource) }
 

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

@@ -151,6 +151,10 @@ internal object TestFhirEngineImpl : FhirEngine {
     return Patient()
   }
 
+  override suspend fun get(type: ResourceType, vararg ids: String): List<Resource> {
+    return ids.map { Patient() }
+  }
+
   override suspend fun delete(type: ResourceType, id: String) {}
 
   override suspend fun <R : Resource> search(search: Search): List<SearchResult<R>> {