diff --git a/src/main/java/li/strolch/agent/impl/TransactionalElementMap.java b/src/main/java/li/strolch/agent/impl/TransactionalElementMap.java
index e1c0fce66..bc3f64a36 100644
--- a/src/main/java/li/strolch/agent/impl/TransactionalElementMap.java
+++ b/src/main/java/li/strolch/agent/impl/TransactionalElementMap.java
@@ -25,8 +25,7 @@ public abstract class TransactionalElementMap<T extends StrolchElement> implemen
 
 	@Override
 	public boolean hasElement(StrolchTransaction tx, String type, String id) {
-		// TODO change to dao.hasElement(type, id)
-		return getDao(tx).queryKeySet(type).contains(id);
+		return getDao(tx).hasElement(type, id);
 	}
 
 	@Override
diff --git a/src/main/java/li/strolch/persistence/api/StrolchDao.java b/src/main/java/li/strolch/persistence/api/StrolchDao.java
index cefb8e458..c4676ba05 100644
--- a/src/main/java/li/strolch/persistence/api/StrolchDao.java
+++ b/src/main/java/li/strolch/persistence/api/StrolchDao.java
@@ -27,7 +27,7 @@ public interface StrolchDao<T extends StrolchElement> {
 
 	public Set<String> queryKeySet();
 
-	// TODO add method hasElement(String type, String id)
+	public boolean hasElement(String type, String id);
 
 	public long querySize();
 
diff --git a/src/main/java/li/strolch/persistence/inmemory/InMemoryDao.java b/src/main/java/li/strolch/persistence/inmemory/InMemoryDao.java
index c7a96a702..ae7277cbe 100644
--- a/src/main/java/li/strolch/persistence/inmemory/InMemoryDao.java
+++ b/src/main/java/li/strolch/persistence/inmemory/InMemoryDao.java
@@ -2,7 +2,6 @@ package li.strolch.persistence.inmemory;
 
 import java.text.MessageFormat;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
@@ -21,6 +20,14 @@ public class InMemoryDao<T extends StrolchElement> implements StrolchDao<T> {
 		this.elementMap = new HashMap<>();
 	}
 
+	@Override
+	public boolean hasElement(String type, String id) {
+		Map<String, T> byType = this.elementMap.get(type);
+		if (byType == null)
+			return false;
+		return byType.containsKey(id);
+	}
+
 	@Override
 	public long querySize() {
 		long size = 0;
@@ -57,7 +64,7 @@ public class InMemoryDao<T extends StrolchElement> implements StrolchDao<T> {
 	public Set<String> queryKeySet(String type) {
 		Map<String, T> byType = this.elementMap.get(type);
 		if (byType == null)
-			return Collections.emptySet();
+			return new HashSet<>(0);
 		return new HashSet<>(byType.keySet());
 	}
 
@@ -91,7 +98,7 @@ public class InMemoryDao<T extends StrolchElement> implements StrolchDao<T> {
 	public List<T> queryAll(String type) {
 		Map<String, T> byType = this.elementMap.get(type);
 		if (byType == null)
-			return Collections.emptyList();
+			return new ArrayList<>(0);
 		return new ArrayList<>(byType.values());
 	}