diff --git a/db/src/main/java/de/muehlencord/shared/db/AbstractController.java b/db/src/main/java/de/muehlencord/shared/db/AbstractController.java
index 0821833..1112d53 100644
--- a/db/src/main/java/de/muehlencord/shared/db/AbstractController.java
+++ b/db/src/main/java/de/muehlencord/shared/db/AbstractController.java
@@ -15,6 +15,7 @@
  */
 package de.muehlencord.shared.db;
 
+import de.muehlencord.shared.util.DateUtil;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Date;
@@ -89,9 +90,8 @@ public abstract class AbstractController<T> {
      * @param cb the criteria builder to use
      * @param root the root of the object to search for
      * @param filters the filters to apply
-     * @param include if set to true, the filter is used as include filter
-     * (equals, in). If set to false, the filter is inverted and used as exclude
-     * filter (not equals, not in etc)
+     * @param include if set to true, the filter is used as include filter (equals, in). If set to false, the filter is
+     * inverted and used as exclude filter (not equals, not in etc)
      * @return
      */
     protected Predicate getFilterCondition(Predicate filterCondition, CriteriaBuilder cb, Root<T> root, Map<String, Object> filters, boolean include) {
@@ -103,7 +103,15 @@ public abstract class AbstractController<T> {
 
                     // check for differnt types 
                     // 1st String, either from Enum Status or from other free text string
-                    if (String.class.equals(filter.getValue().getClass())) {
+                    if (filter.getValue() == null) {
+                        Predicate predicate;
+                        if (include) {
+                            predicate = cb.isNull(path);
+                        } else {
+                            predicate = cb.isNotNull(path);
+                        }
+                        filterCondition = addFilterCondition(cb, filterCondition, predicate);
+                    } else if (String.class.equals(filter.getValue().getClass())) {
                         switch (filter.getKey()) {
                             default:
                                 String filterValue = filter.getValue().toString();
@@ -204,6 +212,10 @@ public abstract class AbstractController<T> {
             Updateable updateable = (Updateable) entity;
             applyUpdateableChanges(updateable, true, createdBy);
         }
+        if (EndDateable.class.isAssignableFrom(entity.getClass())) {
+            EndDateable endDateable = (EndDateable) entity;
+            endDateable.setValidFrom(DateUtil.getCurrentTimeInUTC());
+        }
         em.persist(entity);
         return entity;
     }
@@ -223,7 +235,14 @@ public abstract class AbstractController<T> {
     @Transactional
     @Lock(LockType.WRITE)
     public void delete(T entity, String deletedBy) throws ControllerException {
-        em.remove(attach(entity));
+        // if the entity is endDateable just set the validToDate to now intead of executing the deletion
+        if (EndDateable.class.isAssignableFrom(entity.getClass())) {
+            EndDateable endDateable = (EndDateable) entity;
+            endDateable.setValidTo(DateUtil.getCurrentTimeInUTC());
+            update(entity, deletedBy);
+        } else {
+            em.remove(attach(entity));
+        }
     }
 
     @Lock(LockType.READ)
@@ -233,18 +252,18 @@ public abstract class AbstractController<T> {
 
     @Lock(LockType.READ)
     public T find(Object id, String... subGraphItems) {
-        EntityGraph graph = this.em.createEntityGraph(entityClass);        
+        EntityGraph graph = this.em.createEntityGraph(entityClass);
         for (String subGraphItem : subGraphItems) {
-            graph.addSubgraph(subGraphItem);                        
+            graph.addSubgraph(subGraphItem);
         }
-        
-        Map hints = new HashMap<>();        
+
+        Map hints = new HashMap<>();
         hints.put("javax.persistence.loadgraph", graph);
 
         T entity = (T) em.find(entityClass, id, hints);
         return entity;
     }
-    
+
     @Lock(LockType.READ)
     public List<T> findAll() {
         return findAll(new ArrayList<>());
@@ -287,9 +306,8 @@ public abstract class AbstractController<T> {
     }
 
     /**
-     * returns null, if the list is empty or null itself. Returns the one
-     * element if there is exactly one element in the list. Otherwise an
-     * exception is thrown
+     * returns null, if the list is empty or null itself. Returns the one element if there is exactly one element in the
+     * list. Otherwise an exception is thrown
      *
      * @param resultList
      * @return