Support external type JsonToNative #148

Author: greenrobot-team

objectbox/CHANGELOG.md

@@ -6,6 +6,8 @@
   sure to update to `io.objectbox:objectbox-android-objectbrowser:4.3.0` in `android/app/build.gradle`.
 * Update ObjectBox database for Flutter iOS/macOS apps to 4.3.0.
   For existing projects, run `pod repo update` and `pod update ObjectBox` in the `ios` or `macos` directories.
+* External property types (via [MongoDB connector](https://sync.objectbox.io/mongodb-sync-connector)):
+  add `jsonToNative` to support sub (embedded/nested) documents/arrays in MongoDB.
 
 ## 4.2.0 (2025-04-15)
 

objectbox/lib/src/annotations.dart

@@ -593,6 +593,19 @@ enum ExternalPropertyType {
   /// Representing type: String
   javaScript,
 
+  /// A JSON string that is converted to a native representation in the external
+  /// system.
+  ///
+  /// For example, a JSON object on the ObjectBox side (string) would be
+  /// converted to an embedded document in MongoDB.
+  ///
+  /// It depends on the external system what kind of JSON structures is
+  /// supported. For MongoDB, this is very flexible and allows (nested) objects,
+  /// arrays, primitives, etc.
+  ///
+  /// Representing type: String
+  jsonToNative,
+
   /// A vector (array) of Int128 values.
   int128Vector,
 

objectbox/lib/src/modelinfo/enums.dart

@@ -258,6 +258,8 @@ int externalTypeToOBXExternalType(ExternalPropertyType type) {
       return OBXExternalPropertyType.Bson;
     case ExternalPropertyType.javaScript:
       return OBXExternalPropertyType.JavaScript;
+    case ExternalPropertyType.jsonToNative:
+      return OBXExternalPropertyType.JsonToNative;
     case ExternalPropertyType.int128Vector:
       return OBXExternalPropertyType.Int128Vector;
     case ExternalPropertyType.uuidVector:

objectbox_test/test/entity.dart

@@ -490,6 +490,9 @@ class EntityWithExternalType {
   @ExternalName(name: 'my-mongo-rel')
   final mongoIdEntities = ToMany<EntityWithExternalType>();
 
+  @ExternalType(type: ExternalPropertyType.jsonToNative)
+  String? externalJsonToNative;
+
   EntityWithExternalType(this.mongoId, this.mongoUuid);
 }
 

objectbox_test/test/objectbox-model.json

@@ -727,7 +727,7 @@
     },
     {
       "id": "16:5931645853908059165",
-      "lastPropertyId": "3:7670802129899081197",
+      "lastPropertyId": "4:6250975810854368520",
       "name": "EntityWithExternalType",
       "externalName": "my-mongo-entity",
       "properties": [
@@ -749,6 +749,12 @@
           "type": 27,
           "externalType": 102,
           "externalName": "my-mongo-uuid"
+        },
+        {
+          "id": "4:6250975810854368520",
+          "name": "externalJsonToNative",
+          "type": 9,
+          "externalType": 112
         }
       ],
       "relations": [