[New][Devel] Work in progress of implementing ActivityMap

- Implemented PostgreSQL persistence

Still missing is the xml persistence implementation and fixing
the tests. Currently no tests were run, just trying to fix compile
errors

li.strolch.model/src/main/java/li/strolch/model/xml/ActivityToSaxVisitor.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2015 Robert von Burg <eitch@eitchnet.ch>
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package li.strolch.model.xml;
+
+import java.text.MessageFormat;
+
+import li.strolch.model.ActivityVisitor;
+import li.strolch.model.Tags;
+import li.strolch.model.activity.Activity;
+
+import org.xml.sax.ContentHandler;
+
+/**
+ * @author Robert von Burg <eitch@eitchnet.ch>
+ */
+public class ActivityToSaxVisitor extends StrolchElementToSaxVisitor implements ActivityVisitor<Void> {
+
+	public ActivityToSaxVisitor(ContentHandler contentHandler) {
+		super(contentHandler);
+	}
+
+	@Override
+	public Void visit(Activity activity) {
+		try {
+
+			this.contentHandler.startElement(null, null, Tags.ACTIVITY, attributesFor(activity));
+			toSax(activity);
+			this.contentHandler.endElement(null, null, Tags.ACTIVITY);
+
+		} catch (Exception e) {
+			String msg = "Failed to transform Activity {0} to XML due to {1}"; //$NON-NLS-1$
+			msg = MessageFormat.format(msg, activity.getLocator(), e.getMessage());
+			throw new RuntimeException(msg, e);
+		}
+
+		return null;
+	}
+}

li.strolch.persistence.postgresql/src/main/java/li/strolch/persistence/postgresql/PostgreSqlActivityDao.java

@@ -0,0 +1,179 @@
+/*
+ * Copyright 2015 Robert von Burg <eitch@eitchnet.ch>
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package li.strolch.persistence.postgresql;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.SQLXML;
+import java.text.MessageFormat;
+import java.util.ArrayList;
+import java.util.List;
+
+import javax.xml.parsers.ParserConfigurationException;
+import javax.xml.parsers.SAXParser;
+import javax.xml.parsers.SAXParserFactory;
+import javax.xml.transform.sax.SAXResult;
+
+import li.strolch.model.ActivityVisitor;
+import li.strolch.model.Tags;
+import li.strolch.model.activity.Activity;
+import li.strolch.model.query.ActivityQuery;
+import li.strolch.model.xml.ActivityToSaxVisitor;
+import li.strolch.model.xml.SimpleStrolchElementListener;
+import li.strolch.model.xml.XmlModelSaxReader;
+import li.strolch.persistence.api.ActivityDao;
+import li.strolch.persistence.api.StrolchPersistenceException;
+
+import org.xml.sax.ContentHandler;
+import org.xml.sax.SAXException;
+
+@SuppressWarnings("nls")
+public class PostgreSqlActivityDao extends PostgresqlDao<Activity> implements ActivityDao {
+
+	public static final String ACTIVITIES = "activities";
+
+	protected PostgreSqlActivityDao(PostgreSqlStrolchTransaction tx) {
+		super(tx);
+	}
+
+	@Override
+	protected String getClassName() {
+		return Tags.ACTIVITY;
+	}
+
+	@Override
+	protected String getTableName() {
+		return ACTIVITIES;
+	}
+
+	@Override
+	protected Activity parseFromXml(String id, String type, SQLXML sqlxml) {
+		SimpleStrolchElementListener listener = new SimpleStrolchElementListener();
+		try (InputStream binaryStream = sqlxml.getBinaryStream()) {
+			SAXParser parser = SAXParserFactory.newInstance().newSAXParser();
+			parser.parse(binaryStream, new XmlModelSaxReader(listener));
+		} catch (SQLException | IOException | SAXException | ParserConfigurationException e) {
+			throw new StrolchPersistenceException(MessageFormat.format(
+					"Failed to extract Activity from sqlxml value for {0} / {1}", id, type), e);
+		}
+
+		if (listener.getActivities().size() == 0)
+			throw new StrolchPersistenceException(MessageFormat.format(
+					"No Activity parsed from sqlxml value for {0} / {1}", id, type));
+		if (listener.getActivities().size() > 1)
+			throw new StrolchPersistenceException(MessageFormat.format(
+					"Multiple Activities parsed from sqlxml value for {0} / {1}", id, type));
+
+		return listener.getActivities().get(0);
+	}
+
+	protected SQLXML createSqlXml(Activity activity, PreparedStatement preparedStatement) throws SQLException,
+			SAXException {
+		SQLXML sqlxml = tx().getConnection().createSQLXML();
+		SAXResult saxResult = sqlxml.setResult(SAXResult.class);
+		ContentHandler contentHandler = saxResult.getHandler();
+		contentHandler.startDocument();
+		new ActivityToSaxVisitor(contentHandler).visit(activity);
+		contentHandler.endDocument();
+		return sqlxml;
+	}
+
+	@Override
+	protected void internalSave(final Activity activity) {
+		String sql = "insert into " + getTableName() + " (id, name, type, asxml) values (?, ?, ?, ?)";
+		try (PreparedStatement preparedStatement = tx().getConnection().prepareStatement(sql)) {
+			preparedStatement.setString(1, activity.getId());
+			preparedStatement.setString(2, activity.getName());
+			preparedStatement.setString(3, activity.getType());
+
+			SQLXML sqlxml = createSqlXml(activity, preparedStatement);
+			preparedStatement.setSQLXML(4, sqlxml);
+			try {
+				int modCount = preparedStatement.executeUpdate();
+				if (modCount != 1) {
+					String msg = "Expected to save 1 element with id {0} but SQL statement modified {1} elements!";
+					msg = MessageFormat.format(msg, activity.getId(), modCount);
+					throw new StrolchPersistenceException(msg);
+				}
+			} finally {
+				sqlxml.free();
+			}
+
+		} catch (SQLException | SAXException e) {
+			throw new StrolchPersistenceException(MessageFormat.format("Failed to insert Activity {0} due to {1}",
+					activity.getLocator(), e.getLocalizedMessage()), e);
+		}
+	}
+
+	@Override
+	protected void internalUpdate(final Activity activity) {
+		String sql = "update " + getTableName() + " set name = ?, type = ?, asxml = ? where id = ? ";
+		try (PreparedStatement preparedStatement = tx().getConnection().prepareStatement(sql)) {
+
+			preparedStatement.setString(1, activity.getName());
+			preparedStatement.setString(2, activity.getType());
+			preparedStatement.setString(4, activity.getId());
+
+			SQLXML sqlxml = createSqlXml(activity, preparedStatement);
+			preparedStatement.setSQLXML(3, sqlxml);
+			try {
+				int modCount = preparedStatement.executeUpdate();
+				if (modCount != 1) {
+					String msg = "Expected to update 1 element with id {0} but SQL statement modified {1} elements!";
+					msg = MessageFormat.format(msg, activity.getId(), modCount);
+					throw new StrolchPersistenceException(msg);
+				}
+			} finally {
+				sqlxml.free();
+			}
+
+		} catch (SQLException | SAXException e) {
+			throw new StrolchPersistenceException(MessageFormat.format("Failed to update Activity {0} due to {1}",
+					activity.getLocator(), e.getLocalizedMessage()), e);
+		}
+	}
+
+	@Override
+	public <U> List<U> doQuery(ActivityQuery query, ActivityVisitor<U> activityVisitor) {
+
+		PostgreSqlActivityQueryVisitor queryVisitor = new PostgreSqlActivityQueryVisitor("id, asxml");
+		query.accept(queryVisitor);
+		queryVisitor.validate();
+
+		List<U> list = new ArrayList<>();
+
+		String sql = queryVisitor.getSql();
+		try (PreparedStatement ps = tx().getConnection().prepareStatement(sql)) {
+			queryVisitor.setValues(ps);
+
+			try (ResultSet result = ps.executeQuery()) {
+				while (result.next()) {
+					String id = result.getString("id");
+					SQLXML sqlxml = result.getSQLXML("asxml");
+					Activity t = parseFromXml(id, queryVisitor.getType(), sqlxml);
+					list.add(activityVisitor.visit(t));
+				}
+			}
+		} catch (SQLException e) {
+			throw new StrolchPersistenceException("Failed to perform query due to: " + e.getMessage(), e);
+		}
+
+		return list;
+	}
+}

li.strolch.persistence.postgresql/src/main/java/li/strolch/persistence/postgresql/PostgreSqlActivityQueryVisitor.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2015 Robert von Burg <eitch@eitchnet.ch>
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package li.strolch.persistence.postgresql;
+
+import li.strolch.model.Tags;
+import li.strolch.model.query.ActivityQueryVisitor;
+
+/**
+ * @author Robert von Burg <eitch@eitchnet.ch>
+ */
+public class PostgreSqlActivityQueryVisitor extends PostgreSqlQueryVisitor implements ActivityQueryVisitor {
+
+	/**
+	 * @param fields
+	 */
+	public PostgreSqlActivityQueryVisitor(String fields) {
+		super(fields);
+	}
+
+	@Override
+	protected String getClassName() {
+		return Tags.ACTIVITY;
+	}
+
+	@Override
+	protected String getTableName() {
+		return PostgreSqlActivityDao.ACTIVITIES;
+	}
+}

li.strolch.persistence.postgresql/src/main/java/li/strolch/persistence/postgresql/PostgreSqlOrderDao.java

@@ -50,9 +50,6 @@ public class PostgreSqlOrderDao extends PostgresqlDao<Order> implements OrderDao
 
 	public static final String ORDERS = "orders";
 
-	/**
-	 * @param tx
-	 */
 	public PostgreSqlOrderDao(PostgreSqlStrolchTransaction tx) {
 		super(tx);
 	}
@@ -89,7 +86,7 @@ public class PostgreSqlOrderDao extends PostgresqlDao<Order> implements OrderDao
 	}
 
 	protected SQLXML createSqlXml(Order order, PreparedStatement preparedStatement) throws SQLException, SAXException {
-		SQLXML sqlxml = this.tx.getConnection().createSQLXML();
+		SQLXML sqlxml = tx().getConnection().createSQLXML();
 		SAXResult saxResult = sqlxml.setResult(SAXResult.class);
 		ContentHandler contentHandler = saxResult.getHandler();
 		contentHandler.startDocument();
@@ -102,7 +99,7 @@ public class PostgreSqlOrderDao extends PostgresqlDao<Order> implements OrderDao
 	protected void internalSave(final Order order) {
 		String sql = "insert into " + getTableName()
 				+ " (id, name, type, state, date, asxml) values (?, ?, ?, ?::order_state, ?, ?)";
-		try (PreparedStatement preparedStatement = PostgreSqlOrderDao.this.tx.getConnection().prepareStatement(sql)) {
+		try (PreparedStatement preparedStatement = tx().getConnection().prepareStatement(sql)) {
 			preparedStatement.setString(1, order.getId());
 			preparedStatement.setString(2, order.getName());
 			preparedStatement.setString(3, order.getType());
@@ -132,7 +129,7 @@ public class PostgreSqlOrderDao extends PostgresqlDao<Order> implements OrderDao
 	protected void internalUpdate(final Order order) {
 		String sql = "update " + getTableName()
 				+ " set name = ?, type = ?, state = ?::order_state, date = ?, asxml = ? where id = ? ";
-		try (PreparedStatement preparedStatement = PostgreSqlOrderDao.this.tx.getConnection().prepareStatement(sql)) {
+		try (PreparedStatement preparedStatement = tx().getConnection().prepareStatement(sql)) {
 
 			preparedStatement.setString(1, order.getName());
 			preparedStatement.setString(2, order.getType());
@@ -169,7 +166,7 @@ public class PostgreSqlOrderDao extends PostgresqlDao<Order> implements OrderDao
 		List<U> list = new ArrayList<>();
 
 		String sql = queryVisitor.getSql();
-		try (PreparedStatement ps = PostgreSqlOrderDao.this.tx.getConnection().prepareStatement(sql)) {
+		try (PreparedStatement ps = tx().getConnection().prepareStatement(sql)) {
 			queryVisitor.setValues(ps);
 
 			try (ResultSet result = ps.executeQuery()) {

li.strolch.persistence.postgresql/src/main/java/li/strolch/persistence/postgresql/PostgreSqlPersistenceHandler.java

@@ -33,6 +33,7 @@ import li.strolch.agent.api.RealmHandler;
 import li.strolch.agent.api.StrolchAgent;
 import li.strolch.agent.api.StrolchComponent;
 import li.strolch.agent.api.StrolchRealm;
+import li.strolch.persistence.api.ActivityDao;
 import li.strolch.persistence.api.AuditDao;
 import li.strolch.persistence.api.OrderDao;
 import li.strolch.persistence.api.PersistenceHandler;
@@ -155,6 +156,11 @@ public class PostgreSqlPersistenceHandler extends StrolchComponent implements Pe
 		return ((PostgreSqlStrolchTransaction) tx).getResourceDao();
 	}
 
+	@Override
+	public ActivityDao getActivityDao(StrolchTransaction tx) {
+		return ((PostgreSqlStrolchTransaction) tx).getActivityDao();
+	}
+	
 	@Override
 	public AuditDao getAuditDao(StrolchTransaction tx) {
 		return ((PostgreSqlStrolchTransaction) tx).getAuditDao();

li.strolch.persistence.postgresql/src/main/java/li/strolch/persistence/postgresql/PostgreSqlResourceDao.java

@@ -84,7 +84,7 @@ public class PostgreSqlResourceDao extends PostgresqlDao<Resource> implements Re
 	}
 
 	protected SQLXML createSqlXml(Resource res, PreparedStatement preparedStatement) throws SQLException, SAXException {
-		SQLXML sqlxml = this.tx.getConnection().createSQLXML();
+		SQLXML sqlxml = tx().getConnection().createSQLXML();
 		SAXResult saxResult = sqlxml.setResult(SAXResult.class);
 		ContentHandler contentHandler = saxResult.getHandler();
 		contentHandler.startDocument();
@@ -96,7 +96,7 @@ public class PostgreSqlResourceDao extends PostgresqlDao<Resource> implements Re
 	@Override
 	protected void internalSave(final Resource res) {
 		String sql = "insert into " + getTableName() + " (id, name, type, asxml) values (?, ?, ?, ?)";
-		try (PreparedStatement preparedStatement = PostgreSqlResourceDao.this.tx.getConnection().prepareStatement(sql)) {
+		try (PreparedStatement preparedStatement = tx().getConnection().prepareStatement(sql)) {
 			preparedStatement.setString(1, res.getId());
 			preparedStatement.setString(2, res.getName());
 			preparedStatement.setString(3, res.getType());
@@ -123,7 +123,7 @@ public class PostgreSqlResourceDao extends PostgresqlDao<Resource> implements Re
 	@Override
 	protected void internalUpdate(final Resource resource) {
 		String sql = "update " + getTableName() + " set name = ?, type = ?, asxml = ? where id = ? ";
-		try (PreparedStatement preparedStatement = PostgreSqlResourceDao.this.tx.getConnection().prepareStatement(sql)) {
+		try (PreparedStatement preparedStatement = tx().getConnection().prepareStatement(sql)) {
 
 			preparedStatement.setString(1, resource.getName());
 			preparedStatement.setString(2, resource.getType());
@@ -158,7 +158,7 @@ public class PostgreSqlResourceDao extends PostgresqlDao<Resource> implements Re
 		List<U> list = new ArrayList<>();
 
 		String sql = queryVisitor.getSql();
-		try (PreparedStatement ps = PostgreSqlResourceDao.this.tx.getConnection().prepareStatement(sql)) {
+		try (PreparedStatement ps = tx().getConnection().prepareStatement(sql)) {
 			queryVisitor.setValues(ps);
 
 			try (ResultSet result = ps.executeQuery()) {

li.strolch.persistence.postgresql/src/main/java/li/strolch/persistence/postgresql/PostgreSqlStrolchTransaction.java

@@ -19,6 +19,7 @@ import java.sql.Connection;
 
 import li.strolch.agent.api.StrolchRealm;
 import li.strolch.persistence.api.AbstractTransaction;
+import li.strolch.persistence.api.ActivityDao;
 import li.strolch.persistence.api.AuditDao;
 import li.strolch.persistence.api.OrderDao;
 import li.strolch.persistence.api.PersistenceHandler;
@@ -36,8 +37,9 @@ public class PostgreSqlStrolchTransaction extends AbstractTransaction {
 	private static final Logger logger = LoggerFactory.getLogger(PostgreSqlStrolchTransaction.class);
 	private PostgreSqlPersistenceHandler persistenceHandler;
 
-	private PostgresqlDao<?> orderDao;
-	private PostgresqlDao<?> resourceDao;
+	private PostgreSqlOrderDao orderDao;
+	private PostgreSqlResourceDao resourceDao;
+	private PostgreSqlActivityDao activityDao;
 	private AuditDao auditDao;
 	private Connection connection;
 
@@ -94,9 +96,12 @@ public class PostgreSqlStrolchTransaction extends AbstractTransaction {
 		return (ResourceDao) this.resourceDao;
 	}
 
-	/**
-	 * @return
-	 */
+	ActivityDao getActivityDao() {
+		if (this.activityDao == null)
+			this.activityDao = new PostgreSqlActivityDao(this);
+		return (ActivityDao) this.activityDao;
+	}
+
 	public AuditDao getAuditDao() {
 		if (this.auditDao == null)
 			this.auditDao = new PostgreSqlAuditDao(this);
@@ -114,5 +119,4 @@ public class PostgreSqlStrolchTransaction extends AbstractTransaction {
 	public PersistenceHandler getPersistenceHandler() {
 		return this.persistenceHandler;
 	}
-
 }

li.strolch.persistence.postgresql/src/main/java/li/strolch/persistence/postgresql/PostgresqlDao.java

@@ -41,6 +41,10 @@ public abstract class PostgresqlDao<T extends StrolchElement> implements Strolch
 		this.commands = new ArrayList<>();
 	}
 
+	protected PostgreSqlStrolchTransaction tx() {
+		return this.tx;
+	}
+
 	protected abstract String getClassName();
 
 	protected abstract String getTableName();
@@ -50,7 +54,7 @@ public abstract class PostgresqlDao<T extends StrolchElement> implements Strolch
 	@Override
 	public boolean hasElement(String type, String id) {
 		String sql = "select count(*) from " + getTableName() + " where type = ? and id = ?";
-		try (PreparedStatement statement = this.tx.getConnection().prepareStatement(sql)) {
+		try (PreparedStatement statement = tx().getConnection().prepareStatement(sql)) {
 			statement.setString(1, type);
 			statement.setString(2, id);
 			try (ResultSet result = statement.executeQuery()) {
@@ -72,7 +76,7 @@ public abstract class PostgresqlDao<T extends StrolchElement> implements Strolch
 	@Override
 	public long querySize() {
 		String sql = "select count(*) from " + getTableName();
-		try (PreparedStatement statement = this.tx.getConnection().prepareStatement(sql)) {
+		try (PreparedStatement statement = tx().getConnection().prepareStatement(sql)) {
 			try (ResultSet result = statement.executeQuery()) {
 				result.next();
 				return result.getLong(1);
@@ -85,7 +89,7 @@ public abstract class PostgresqlDao<T extends StrolchElement> implements Strolch
 	@Override
 	public long querySize(String type) {
 		String sql = "select count(*) from " + getTableName() + " where type = ?";
-		try (PreparedStatement statement = this.tx.getConnection().prepareStatement(sql)) {
+		try (PreparedStatement statement = tx().getConnection().prepareStatement(sql)) {
 			statement.setString(1, type);
 			try (ResultSet result = statement.executeQuery()) {
 				result.next();
@@ -102,7 +106,7 @@ public abstract class PostgresqlDao<T extends StrolchElement> implements Strolch
 		Set<String> keySet = new HashSet<>();
 
 		String sql = "select id from " + getTableName();
-		try (PreparedStatement statement = this.tx.getConnection().prepareStatement(sql)) {
+		try (PreparedStatement statement = tx().getConnection().prepareStatement(sql)) {
 			try (ResultSet result = statement.executeQuery()) {
 				while (result.next()) {
 					keySet.add(result.getString("id"));
@@ -120,7 +124,7 @@ public abstract class PostgresqlDao<T extends StrolchElement> implements Strolch
 		Set<String> keySet = new HashSet<>();
 
 		String sql = "select id from " + getTableName() + " where type = ?";
-		try (PreparedStatement statement = this.tx.getConnection().prepareStatement(sql)) {
+		try (PreparedStatement statement = tx().getConnection().prepareStatement(sql)) {
 			statement.setString(1, type);
 			try (ResultSet result = statement.executeQuery()) {
 				while (result.next()) {
@@ -139,7 +143,7 @@ public abstract class PostgresqlDao<T extends StrolchElement> implements Strolch
 		Set<String> keySet = new HashSet<>();
 
 		String sql = "select distinct type from " + getTableName();
-		try (PreparedStatement statement = this.tx.getConnection().prepareStatement(sql)) {
+		try (PreparedStatement statement = tx().getConnection().prepareStatement(sql)) {
 			try (ResultSet result = statement.executeQuery()) {
 				while (result.next()) {
 					keySet.add(result.getString("type"));
@@ -156,7 +160,7 @@ public abstract class PostgresqlDao<T extends StrolchElement> implements Strolch
 	public T queryBy(String type, String id) {
 
 		String sql = "select id, name, type, asxml from " + getTableName() + " where id = ? and type = ?";
-		try (PreparedStatement statement = this.tx.getConnection().prepareStatement(sql)) {
+		try (PreparedStatement statement = tx().getConnection().prepareStatement(sql)) {
 			statement.setString(1, id);
 			statement.setString(2, type);
 			try (ResultSet result = statement.executeQuery()) {
@@ -180,7 +184,7 @@ public abstract class PostgresqlDao<T extends StrolchElement> implements Strolch
 
 		List<T> list = new ArrayList<>();
 		String sql = "select id, name, type, asxml from " + getTableName();
-		try (PreparedStatement statement = this.tx.getConnection().prepareStatement(sql)) {
+		try (PreparedStatement statement = tx().getConnection().prepareStatement(sql)) {
 			try (ResultSet result = statement.executeQuery()) {
 				while (result.next()) {
 					String id = result.getString("id");
@@ -202,7 +206,7 @@ public abstract class PostgresqlDao<T extends StrolchElement> implements Strolch
 
 		List<T> list = new ArrayList<>();
 		String sql = "select id, name, type, asxml from " + getTableName() + " where type = ?";
-		try (PreparedStatement statement = this.tx.getConnection().prepareStatement(sql)) {
+		try (PreparedStatement statement = tx().getConnection().prepareStatement(sql)) {
 			statement.setString(1, type);
 			try (ResultSet result = statement.executeQuery()) {
 				while (result.next()) {
@@ -335,7 +339,7 @@ public abstract class PostgresqlDao<T extends StrolchElement> implements Strolch
 
 	protected void internalRemove(final T element) {
 		String sql = "delete from " + getTableName() + " where id = ?";
-		try (PreparedStatement preparedStatement = this.tx.getConnection().prepareStatement(sql)) {
+		try (PreparedStatement preparedStatement = tx().getConnection().prepareStatement(sql)) {
 
 			preparedStatement.setString(1, element.getId());
 			int modCount = preparedStatement.executeUpdate();
@@ -353,7 +357,7 @@ public abstract class PostgresqlDao<T extends StrolchElement> implements Strolch
 
 	protected void internalRemoveAll(final long toRemove) {
 		String sql = "delete from " + getTableName();
-		try (PreparedStatement preparedStatement = this.tx.getConnection().prepareStatement(sql)) {
+		try (PreparedStatement preparedStatement = tx().getConnection().prepareStatement(sql)) {
 			int modCount = preparedStatement.executeUpdate();
 			if (modCount != toRemove) {
 				String msg = "Expected to delete {0} elements but SQL statement removed {1} elements!";
@@ -369,7 +373,7 @@ public abstract class PostgresqlDao<T extends StrolchElement> implements Strolch
 
 	protected void internalRemoveAllBy(final long toRemove, String type) {
 		String sql = "delete from " + getTableName() + " where type = ?";
-		try (PreparedStatement preparedStatement = this.tx.getConnection().prepareStatement(sql)) {
+		try (PreparedStatement preparedStatement = tx().getConnection().prepareStatement(sql)) {
 			preparedStatement.setString(1, type);
 			int modCount = preparedStatement.executeUpdate();
 			if (modCount != toRemove) {