diff --git a/ccm-core/src/main/java/org/libreccm/exchange/exporter/ObjectExporter.java b/ccm-core/src/main/java/org/libreccm/exchange/exporter/ObjectExporter.java
index b6dc2a927..42852fd39 100644
--- a/ccm-core/src/main/java/org/libreccm/exchange/exporter/ObjectExporter.java
+++ b/ccm-core/src/main/java/org/libreccm/exchange/exporter/ObjectExporter.java
@@ -25,7 +25,9 @@ import org.libreccm.security.User;
 
 import java.io.FileWriter;
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.List;
+import java.util.stream.Collectors;
 
 /**
  * Main class for exporting database objects as .csv-textfiles. Subclasses
@@ -101,15 +103,43 @@ public abstract class ObjectExporter<T> {
      * @return  A list of strings containing all database information of the
      *          wanted object class.
      */
-    public abstract List<String[]> asList(List<T> exportObjects);
+    private List<String[]> asList(List<T> exportObjects) {
+        List<String[]> exportList = new ArrayList<>();
+
+        exportList.add(getClassName());
+        exportList.add(getAttributeNames());
+        exportList.addAll(exportObjects.stream().map(
+                this::reduceToStrings).collect(Collectors.toList()));
+
+        return exportList;
+    }
+
+    /**
+     * Abstract method to get the class name for the first line in the
+     * .csv-textfile.
+     *
+     * @return A list containing just one string, the class name
+     */
+    protected abstract String[] getClassName();
+
+    /**
+     * Abstract method to get the class header for the secfirstond line in the
+     * .csv-textfile.
+     *
+     * @return A list of strings representing the object attributes
+     */
+    protected abstract String[] getAttributeNames();
 
     /**
      * Abstract method to reduce the types of a single export object to
-     * strings.
+     * strings. Implementing subclass has to pay attention to attribute
+     * fields containing null values. Null values are not always forbidden,
+     * but when reducing to strings it will cause a NullPointerException, if
+     * not handled accurately.
      *
      * @param exportObject A single exportObject
      * @return  A list of strings representing the parameters of the
      *          export object
      */
-    protected abstract String[] reduceToString(T exportObject);
+    protected abstract String[] reduceToStrings(T exportObject);
 }
diff --git a/ccm-core/src/main/java/org/libreccm/exchange/exporter/docrepo/exchange/exporter/ResourceExporter.java b/ccm-core/src/main/java/org/libreccm/exchange/exporter/docrepo/exchange/exporter/ResourceExporter.java
index aaaea7f5e..970408e7b 100644
--- a/ccm-core/src/main/java/org/libreccm/exchange/exporter/docrepo/exchange/exporter/ResourceExporter.java
+++ b/ccm-core/src/main/java/org/libreccm/exchange/exporter/docrepo/exchange/exporter/ResourceExporter.java
@@ -11,19 +11,17 @@
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
- * You should have received a copy of the GNU Lesser General Public
+ * You should have received list copy of the GNU Lesser General Public
  * License along with this library; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  * MA 02110-1301  USA
  */
-package org.libreccm.exchange.exporter.docrepo.exchange;
+package org.libreccm.exchange.exporter.docrepo.exchange.exporter;
 
 import org.libreccm.exchange.exporter.ObjectExporter;
 import org.libreccm.exchange.exporter.docrepo.Resource;
 
 import java.util.ArrayList;
-import java.util.List;
-import java.util.stream.Collectors;
 
 /**
  * Exporter class for resources. Implements the abstract method of its super.
@@ -33,11 +31,13 @@ import java.util.stream.Collectors;
  */
 public class ResourceExporter extends ObjectExporter<Resource> {
     @Override
-    public List<String[]> asList(List<Resource> exportObjects) {
-        List<String[]> exportList = new ArrayList<>();
+    protected String[] getClassName() {
+        return new String[] {Resource.class.getName()};
+    }
 
-        exportList.add(new String[]{Resource.class.getName()});
-        exportList.add(new String[]{
+    @Override
+    protected String[] getAttributeNames() {
+        return new String[] {
                 "name",
                 "description",
                 "isFolder",
@@ -53,46 +53,31 @@ public class ResourceExporter extends ObjectExporter<Resource> {
                 "modifier_ID",
                 "parent_ID",
                 "repo_ID"
-        });
-
-        return exportList.addAll(exportObjects.stream().map(
-                this::reduceToString).collect(Collectors.toList()))
-                ? exportList : exportList;
+        };
     }
 
     @Override
-    protected String[] reduceToString(Resource exportObject) {
-        return new String[] {
-                // name
-                exportObject.getName(),
-                // description
-                exportObject.getDescription(),
-                // isFolder
-                String.valueOf(exportObject.isFolder()),
-                // path
-                exportObject.getPath(),
-                // mimeType
-                exportObject.getMimeType().toString(),
-                // size
-                String.valueOf(exportObject.getSize()),
-                // blobObject_ID
-                String.valueOf(exportObject.getContent().getBlobObjectId()),
-                // creationDate
-                exportObject.getCreationDate().toString(),
-                // lastModifiedDate
-                exportObject.getLastModifiedDate().toString(),
-                // creationIp
-                exportObject.getCreationIp(),
-                // lastModifiedIp
-                exportObject.getLastModifiedIp(),
-                // creator_ID
-                exportObject.getCreationUser().getName(),
-                // modifier_ID
-                exportObject.getLastModifiedUser().getName(),
-                // parent_ID
-                String.valueOf(exportObject.getParent().getObjectId()),
-                // repo_ID
-                String.valueOf(exportObject.getRepository().getObjectId()),
-        };
+    protected String[] reduceToStrings(Resource exportObject) {
+        ArrayList<String> list = new ArrayList<>();
+        list.add(exportObject.getName());
+        list.add(exportObject.getDescription());
+        list.add(String.valueOf(exportObject.isFolder()));
+        list.add(exportObject.getPath());
+        list.add(exportObject.getMimeType() != null ?
+                 exportObject.getMimeType().toString() : "");
+        list.add(String.valueOf(exportObject.getSize()));
+        list.add(String.valueOf(exportObject.getContent().getBlobObjectId()));
+        list.add(exportObject.getCreationDate() != null ?
+                 exportObject.getCreationDate().toString() : "");
+        list.add(exportObject.getLastModifiedDate() != null ?
+                 exportObject.getLastModifiedDate().toString() : "");
+        list.add(exportObject.getCreationIp());
+        list.add(exportObject.getLastModifiedIp());
+        list.add(exportObject.getCreationUser().getName());
+        list.add(exportObject.getLastModifiedUser().getName());
+        list.add(String.valueOf(exportObject.getParent().getObjectId()));
+        list.add(String.valueOf(exportObject.getRepository().getObjectId()));
+
+        return (String[]) list.toArray();
     }
 }