DO RELEASE

crud-base/src/main/java/info/textgrid/namespaces/middleware/tgcrud/services/tgcrudservice/TGCrudServiceAdaptorManager.java

@@ -274,6 +274,9 @@ public class TGCrudServiceAdaptorManager {
     // NOTE We do omit all existing RDF relations here FOR IMAGES ONLY, because for images there is
     // no need for using more RDF metadata at the moment. We may change this in the future!
     //
+    // NOTE TWO: We MUST keep the TextGrid relations such as isDerivedFrom and
+    // isAlternativeFormatOf!
+    //
     // --------------------------------------------------------------------------------------------
     //
     else if (TextGridMimetypes.IMAGE_SET.contains(format)) {
@@ -297,10 +300,14 @@ public class TGCrudServiceAdaptorManager {
         model.setNsPrefix(EXIF_NAMESPACE_PREFIX, RELATION_EXIF_NAMESPACE);
         model.setNsPrefix(DC_NAMESPACE_PREFIX, RELATION_DC_NAMESPACE);
 
-        // Add empty relation RDF part to metadata, omit old RDF metadata here!
-        // TODO All existing relations are deleted here! Do we really want that? Yes, for the time
-        // being and only for images!
-        theObject.getMetadata().getObject().setRelations(new RelationType());
+        // Add relation type to metadata, if not yet existing. All existing RDF relations are
+        // deleted here, because we see them as internal relations for TextGrid processing. Custom
+        // RDF data must be located elsewhere...
+        RelationType relations = theObject.getMetadata().getObject().getRelations();
+        if (relations == null) {
+          relations = new RelationType();
+        }
+        theObject.getMetadata().getObject().setRelations(relations);
 
         CrudServiceUtilities.serviceLog(CrudService.INFO, METH,
             "Omit existing RDF relations metadata, re-creating EXIT metadata");
@@ -325,10 +332,10 @@ public class TGCrudServiceAdaptorManager {
           String rdfWriterString = rdfWriter.toString();
           rdfWriter.close();
 
-          // Unmarshal and set RDFType again.
           CrudServiceUtilities.serviceLog(CrudService.INFO, METH,
               "Adding EXIF information to metadata");
 
+          // Unmarshal and (re-)set RDFType!
           RdfType rdf = JAXB.unmarshal(new StringReader(rdfWriterString), RdfType.class);
           theObject.getMetadata().getObject().getRelations().setRDF(rdf);
         }