From d2aa17041f26d47ec3843f789d00fedbb20abef0 Mon Sep 17 00:00:00 2001
From: hns <hannesw@gmail.com>
Date: Wed, 5 Mar 2003 14:33:21 +0000
Subject: [PATCH] Several changes/fixes in DbMapping:

* Relation mappings that are overwritten in sub-prototypes no longer override
the parent prototype's Relation object but creates its own Relation
* Generally enable all things to be overwritten in DbMappings that inherit from
another relational DbMapping. That means it should now be possible to really
change lots of things from a parent DbMapping and a child DbMapping.
* Improved property enumeration which now merges properties defined in the
DbMapping inherit chain
* Cleaned up and improved variable naming.
---
 src/helma/objectmodel/db/DbMapping.java   | 196 +++++++++++++---------
 src/helma/objectmodel/db/Node.java        |  51 +++---
 src/helma/objectmodel/db/NodeManager.java |  10 +-
 src/helma/objectmodel/db/Property.java    |   2 +-
 src/helma/objectmodel/db/Relation.java    |  26 +--
 5 files changed, 158 insertions(+), 127 deletions(-)

diff --git a/src/helma/objectmodel/db/DbMapping.java b/src/helma/objectmodel/db/DbMapping.java
index 14d8af5d..f8995ee8 100644
--- a/src/helma/objectmodel/db/DbMapping.java
+++ b/src/helma/objectmodel/db/DbMapping.java
@@ -7,6 +7,7 @@ import helma.framework.core.Application;
 import helma.util.Updatable;
 import helma.util.SystemProperties;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Enumeration;
 import java.util.Iterator;
 import java.util.StringTokenizer;
@@ -28,15 +29,15 @@ public final class DbMapping implements Updatable {
     // properties from where the mapping is read
     SystemProperties props;
 
-    // name of data source to which this mapping writes
-    DbSource source;
+    // name of data dbSource to which this mapping writes
+    DbSource dbSource;
     // name of datasource
-    String sourceName;
+    String dbSourceName;
     // name of db table
-    String table;
+    String tableName;
 
     // list of properties to try for parent
-    ParentInfo[] parent;
+    ParentInfo[] parentInfo;
 
     // Relations describing subnodes and properties.
     Relation subRelation;
@@ -101,7 +102,7 @@ public final class DbMapping implements Updatable {
 	prop2db = new HashMap ();
 	db2prop = new HashMap ();
 
-	parent = null;
+	parentInfo = null;
 
 	idField = null;
     }
@@ -123,7 +124,7 @@ public final class DbMapping implements Updatable {
 	
 	columnMap = new HashMap ();
 
-	parent = null;
+	parentInfo = null;
 
 	idField = null;
 
@@ -145,7 +146,7 @@ public final class DbMapping implements Updatable {
      */
     public synchronized void update () {
 	// read in properties
-	table = props.getProperty ("_table");
+	tableName = props.getProperty ("_table");
 	idgen = props.getProperty ("_idgen");
 	// see if there is a field which specifies the prototype of objects, if different prototypes
 	// can be stored in this table
@@ -153,17 +154,17 @@ public final class DbMapping implements Updatable {
 	// see if this prototype extends (inherits from) any other prototype
 	extendsProto = props.getProperty ("_extends");
 
-	sourceName = props.getProperty ("_db");
-	if (sourceName != null) {
-	    source = app.getDbSource (sourceName);
-	    if (source == null) {
-	        app.logEvent ("*** Data Source for prototype "+typename+" does not exist: "+sourceName);
+	dbSourceName = props.getProperty ("_db");
+	if (dbSourceName != null) {
+	    dbSource = app.getDbSource (dbSourceName);
+	    if (dbSource == null) {
+	        app.logEvent ("*** Data Source for prototype "+typename+" does not exist: "+dbSourceName);
 	        app.logEvent ("*** accessing or storing a "+typename+" object will cause an error.");
-	    } else if (table == null) {
+	    } else if (tableName == null) {
 	        app.logEvent ("*** No table name specified for prototype "+typename);
 	        app.logEvent ("*** accessing or storing a "+typename+" object will cause an error.");
-	        // mark mapping as invalid by nulling the source field
-	        source = null;
+	        // mark mapping as invalid by nulling the dbSource field
+	        dbSource = null;
 	    }
 	}
 
@@ -179,11 +180,11 @@ public final class DbMapping implements Updatable {
 	if (parentSpec != null) {
 	    // comma-separated list of properties to be used as parent
 	    StringTokenizer st = new StringTokenizer (parentSpec, ",;");
-	    parent = new ParentInfo[st.countTokens()];
-	    for (int i=0; i<parent.length; i++)
-	        parent[i] = new ParentInfo (st.nextToken().trim());
+	    parentInfo = new ParentInfo[st.countTokens()];
+	    for (int i=0; i<parentInfo.length; i++)
+	        parentInfo[i] = new ParentInfo (st.nextToken().trim());
 	} else {
-	    parent = null;
+	    parentInfo = null;
 	}
 
 	lastTypeChange = props.lastModified ();
@@ -197,8 +198,8 @@ public final class DbMapping implements Updatable {
 	    parentMapping = app.getDbMapping (extendsProto);
 	}
 
-	// if (table != null && source != null) {
-	// app.logEvent ("set data source for "+typename+" to "+source);
+	// if (tableName != null && dbSource != null) {
+	// app.logEvent ("set data dbSource for "+typename+" to "+dbSource);
 	HashMap p2d = new HashMap ();
 	HashMap d2p = new HashMap ();
 
@@ -210,10 +211,13 @@ public final class DbMapping implements Updatable {
 	        if (!propName.startsWith ("_") && propName.indexOf (".") < 0) {
 	            String dbField = props.getProperty (propName);
 	            // check if a relation for this propery already exists. If so, reuse it
-	            Relation rel = propertyToRelation (propName);
+	            Relation rel = (Relation) prop2db.get (propName.toLowerCase());
 	            if (rel == null)
 	                rel = new Relation (dbField, propName, this, props);
 	            rel.update (dbField, props);
+	            // key enumerations from SystemProperties are all lower case, which is why
+	            // even though we don't do a toLowerCase() here,
+	            // we have to when we lookup things in p2d later.
 	            p2d.put (propName, rel);
 	            if (rel.columnName != null &&
 	                    (rel.reftype == Relation.PRIMITIVE ||
@@ -238,7 +242,7 @@ public final class DbMapping implements Updatable {
 	        subRelation.update (subnodeMapping, props);
 	        // if subnodes are accessed via access name or group name,
 	        // the subnode relation is also the property relation.
-	        if (subRelation.accessor != null || subRelation.groupby != null)
+	        if (subRelation.accessName != null || subRelation.groupby != null)
 	            propRelation = subRelation;
 	    } catch (Exception x) {
 	        app.logEvent ("Error reading _subnodes relation for "+typename+": "+x.getMessage ());
@@ -266,18 +270,23 @@ public final class DbMapping implements Updatable {
      * Get a JDBC connection for this DbMapping.
      */
     public Connection getConnection () throws ClassNotFoundException, SQLException {
-	// if source was previously not available, check again
-	if (source == null && sourceName != null)
-	    source = app.getDbSource (sourceName);
-	if (sourceName == null && parentMapping != null)
-	    return parentMapping.getConnection ();
-	if (source == null) {
-	    if (sourceName == null)
-	        throw new SQLException ("Tried to get Connection from non-relational embedded data source.");
+	if (dbSourceName == null) {
+	    if (parentMapping != null)
+	        return parentMapping.getConnection ();
 	    else
-	        throw new SQLException ("Datasource is not defined: "+sourceName+".");
+	        throw new SQLException ("Tried to get Connection from non-relational embedded data source.");
 	}
-	return source.getConnection ();
+	if (tableName == null) {
+	    throw new SQLException ("Invalid DbMapping, _table not specified: "+this);
+	}
+	// if dbSource was previously not available, check again
+	if (dbSource == null) {
+	    dbSource = app.getDbSource (dbSourceName);
+	}
+	if (dbSource == null) {
+	    throw new SQLException ("Datasource is not defined: "+dbSourceName+".");
+	}
+	return dbSource.getConnection ();
     }
 
     /**
@@ -285,27 +294,23 @@ public final class DbMapping implements Updatable {
      * data source including URL, JDBC driver, username and password.
      */
     public DbSource getDbSource () {
-	if (source == null && parentMapping != null)
-	    return parentMapping.getDbSource ();
-	return source;
+	if (dbSource == null) {
+	    if (tableName != null && dbSourceName != null)
+	        dbSource = app.getDbSource (dbSourceName);
+	    else if (parentMapping != null)
+	        return parentMapping.getDbSource ();
+	}
+	return dbSource;
     }
 
-    /**
-     * Get the URL of the data source used for this mapping.
-     */
-    public String getSourceID () {
-	if (source == null && parentMapping != null)
-	    return parentMapping.getSourceID ();
-	return source == null ? "" : source.url;
-    }
 
     /**
      * Get the table name used for this type mapping.
      */
     public String getTableName () {
-	if (source == null && parentMapping != null)
+	if (tableName == null && parentMapping != null)
 	    return parentMapping.getTableName ();
-	return table;
+	return tableName;
     }
 
     /**
@@ -349,7 +354,7 @@ public final class DbMapping implements Updatable {
      * Get the column used for (internal) names of objects of this type.
      */
     public String getNameField () {
-    	if (nameField == null && parentMapping != null)
+	if (nameField == null && parentMapping != null)
 	    return parentMapping.getNameField ();
 	return nameField;
     }
@@ -358,7 +363,7 @@ public final class DbMapping implements Updatable {
      * Get the column used for names of prototype.
      */
     public String getPrototypeField () {
-    	if (protoField == null && parentMapping != null)
+	if (protoField == null && parentMapping != null)
 	    return parentMapping.getPrototypeField ();
 	return protoField;
     }
@@ -370,9 +375,13 @@ public final class DbMapping implements Updatable {
     public String columnNameToProperty (String columnName) {
 	if (columnName == null)
 	    return null;
-	if (table == null && parentMapping != null)
-	    return parentMapping.columnNameToProperty (columnName);
-	Relation rel = (Relation) db2prop.get (columnName.toUpperCase ());
+	return _columnNameToProperty (columnName.toUpperCase());
+    }
+    
+    private String _columnNameToProperty (final String columnName) {
+	Relation rel = (Relation) db2prop.get (columnName);
+	if (rel == null && parentMapping != null)
+	    return parentMapping._columnNameToProperty (columnName);
 	if (rel != null  && (rel.reftype == Relation.PRIMITIVE || rel.reftype == Relation.REFERENCE))
 	    return rel.propName;
 	return null;
@@ -384,11 +393,15 @@ public final class DbMapping implements Updatable {
     public String propertyToColumnName (String propName) {
 	if (propName == null)
 	    return null;
-	if (table == null && parentMapping != null)
-	    return parentMapping.propertyToColumnName (propName);
 	// FIXME: prop2db stores keys in lower case, because it gets them
 	// from a SystemProperties object which converts keys to lower case.
-	Relation rel = (Relation) prop2db.get (propName.toLowerCase());
+	return _propertyToColumnName (propName.toLowerCase ());
+    }
+
+    private String _propertyToColumnName (final String propName) {
+	Relation rel = (Relation) prop2db.get (propName);
+	if (rel == null && parentMapping != null)
+	    return parentMapping._propertyToColumnName (propName);
 	if (rel != null  && (rel.reftype == Relation.PRIMITIVE || rel.reftype == Relation.REFERENCE))
 	    return rel.columnName;
 	return null;
@@ -400,9 +413,14 @@ public final class DbMapping implements Updatable {
     public Relation columnNameToRelation (String columnName) {
 	if (columnName == null)
 	    return null;
-	if (table == null && parentMapping != null)
-	    return parentMapping.columnNameToRelation (columnName);
-	return (Relation) db2prop.get (columnName.toUpperCase ());
+	return _columnNameToRelation (columnName.toUpperCase());
+    }
+    
+    private Relation _columnNameToRelation (final String columnName) {
+	Relation rel = (Relation) db2prop.get (columnName);
+	if (rel == null && parentMapping != null)
+	    return parentMapping._columnNameToRelation (columnName);
+	return rel;
     }
 
     /**
@@ -411,11 +429,16 @@ public final class DbMapping implements Updatable {
     public Relation propertyToRelation (String propName) {
 	if (propName == null)
 	    return null;
-	if (table == null && parentMapping != null)
-	    return parentMapping.propertyToRelation (propName);
 	// FIXME: prop2db stores keys in lower case, because it gets them
 	// from a SystemProperties object which converts keys to lower case.
-	return (Relation) prop2db.get (propName.toLowerCase());
+	return _propertyToRelation (propName.toLowerCase());
+    }
+
+    private Relation _propertyToRelation (String propName) {
+	Relation rel = (Relation) prop2db.get (propName);
+	if (rel == null && parentMapping != null)
+	    return parentMapping._propertyToRelation (propName);
+	return rel;
     }
 
 
@@ -424,17 +447,17 @@ public final class DbMapping implements Updatable {
      * determine its parent object.
      */
     public synchronized ParentInfo[] getParentInfo () {
-    	if (parent == null && parentMapping != null)
-    	    return parentMapping.getParentInfo ();
-	return parent;
+	if (parentInfo == null && parentMapping != null)
+	    return parentMapping.getParentInfo ();
+	return parentInfo;
     }
 
 
     public DbMapping getSubnodeMapping () {
 	if (subRelation != null)
 	    return subRelation.otherType;
-    	if (parentMapping != null)
-    	    return parentMapping.getSubnodeMapping ();
+	if (parentMapping != null)
+	    return parentMapping.getSubnodeMapping ();
 	return null;
     }
 
@@ -551,7 +574,7 @@ public final class DbMapping implements Updatable {
      *  not what we want.
      */
     public boolean isRelational () {
-	if (sourceName != null)
+	if (dbSourceName != null)
 	    return true;
 	if (parentMapping != null)
 	    return parentMapping.isRelational ();
@@ -565,7 +588,7 @@ public final class DbMapping implements Updatable {
     public synchronized DbColumn[] getColumns() throws ClassNotFoundException, SQLException {
 	if (!isRelational ())
 	    throw new SQLException ("Can't get columns for non-relational data mapping "+this);
-	if (source == null && parentMapping != null)
+	if (dbSource == null && parentMapping != null)
 	    return parentMapping.getColumns ();
 	// Use local variable cols to avoid synchronization (schema may be nulled elsewhere)
 	if (columns == null) {
@@ -656,7 +679,7 @@ public final class DbMapping implements Updatable {
      *  to be quoted in SQL queries.
      */
     public boolean needsQuotes (String columnName) throws SQLException {
-	if (table == null && parentMapping != null)
+	if (tableName == null && parentMapping != null)
 	    return parentMapping.needsQuotes (columnName);
 	try {
 	    DbColumn col = getColumn (columnName);
@@ -698,27 +721,38 @@ public final class DbMapping implements Updatable {
 
     public void notifyDataChange () {
 	lastDataChange = System.currentTimeMillis ();
-	if (parentMapping != null && source == null)
+	if (parentMapping != null && dbSource == null)
 	    parentMapping.notifyDataChange ();
     }
 
     public synchronized long getNewID (long dbmax) {
-	if (parentMapping != null && source == null)
+	if (parentMapping != null && dbSource == null)
 	    return parentMapping.getNewID (dbmax);
 	lastID = Math.max (dbmax+1, lastID+1);
 	return lastID;
     }
 
-    public HashMap getProp2DB () {
-	if (table == null && parentMapping != null)
-	    return parentMapping.getProp2DB ();
-	return prop2db;
+    
+    public Enumeration getPropertyEnumeration () {
+	HashSet set = new HashSet ();
+	collectPropertyNames (set);
+	final Iterator it = set.iterator();
+	return new Enumeration () {
+	    public boolean hasMoreElements() {
+	        return it.hasNext();
+	    }
+	    public Object nextElement() {
+	       return it.next();
+	    }
+	};
     }
 
-    public Iterator getDBPropertyIterator () {
-	if (table == null && parentMapping != null)
-	    return parentMapping.getDBPropertyIterator ();
-	return db2prop.values ().iterator ();
+    private void collectPropertyNames (HashSet basket) {
+	// fetch propnames from parent mapping first, than add our own.
+	if (parentMapping != null)
+	    parentMapping.collectPropertyNames (basket);
+	if (!prop2db.isEmpty())
+	    basket.addAll (prop2db.keySet());
     }
 
     /**
@@ -727,9 +761,9 @@ public final class DbMapping implements Updatable {
      * db.
      */
     public String getStorageTypeName () {
-	if (table == null && parentMapping != null)
+	if (tableName == null && parentMapping != null)
 	    return parentMapping.getStorageTypeName ();
-	return sourceName == null ? null : typename;
+	return dbSourceName == null ? null : typename;
     }
 
     /**
diff --git a/src/helma/objectmodel/db/Node.java b/src/helma/objectmodel/db/Node.java
index 2b8ca0d4..a7775c68 100644
--- a/src/helma/objectmodel/db/Node.java
+++ b/src/helma/objectmodel/db/Node.java
@@ -502,8 +502,8 @@ public final class Node implements INode, Serializable {
 	        Node p = parentHandle.getNode (nmgr);
 	        DbMapping parentmap = p.getDbMapping ();
 	        Relation prel = parentmap.getPropertyRelation();
-	        if (prel != null && prel.subnodesAreProperties && prel.accessor != null) {
-	            String propname = dbmap.columnNameToProperty (prel.accessor);
+	        if (prel != null && prel.hasAccessName()) {
+	            String propname = dbmap.columnNameToProperty (prel.accessName);
 	            String propvalue = getString (propname);
 	            if (propvalue != null && propvalue.length() > 0) {
 	                setName (propvalue);
@@ -664,9 +664,9 @@ public final class Node implements INode, Serializable {
 	    if (parentmap != null) {
 	        // first try to retrieve name via generic property relation of parent
 	        Relation prel = parentmap.getPropertyRelation ();
-	        if (prel != null && prel.otherType == dbmap && prel.accessor != null) {
+	        if (prel != null && prel.otherType == dbmap && prel.accessName != null) {
 	            // reverse look up property used to access this via parent
-	            Relation proprel = dbmap.columnNameToRelation (prel.accessor);
+	            Relation proprel = dbmap.columnNameToRelation (prel.accessName);
 	            if (proprel != null && proprel.propName != null)
 	                newname = getString (proprel.propName);
 	        }
@@ -773,17 +773,18 @@ public final class Node implements INode, Serializable {
 	        checkWriteLock ();
 	    node.checkWriteLock ();
 	}
-	
+
 	// if subnodes are defined via realation, make sure its constraints are enforced.
-	if (dbmap != null && dbmap.getSubnodeRelation () != null)
+	if (dbmap != null && dbmap.getSubnodeRelation () != null) {
 	    dbmap.getSubnodeRelation ().setConstraints (this, node);
-	
+	}
+
 	// if the new node is marked as TRANSIENT and this node is not, mark new node as NEW
 	if (state != TRANSIENT && node.state == TRANSIENT)
 	    node.makePersistentCapable ();
 
 	String n = node.getName();
-	
+
 	// if (n.indexOf('/') > -1)
 	//     throw new RuntimeException ("\"/\" found in Node name.");
 
@@ -809,7 +810,7 @@ public final class Node implements INode, Serializable {
 	        if (groupbyNode == null)
 	            groupbyNode = getGroupbySubnode (groupbyValue, true);
 	        groupbyNode.addNode (node);
-	
+
 	        return node;
 	    } catch (Exception x) {
 	        System.err.println ("Error adding groupby: "+x);
@@ -836,10 +837,10 @@ public final class Node implements INode, Serializable {
 	    // check if properties are subnodes (_properties.aresubnodes=true)
 	    if (dbmap != null && node.dbmap != null) {
 	        Relation prel = dbmap.getPropertyRelation();
-	        if (prel != null && prel.accessor != null) {
-	            Relation localrel = node.dbmap.columnNameToRelation (prel.accessor);
+	        if (prel != null && prel.accessName != null) {
+	            Relation localrel = node.dbmap.columnNameToRelation (prel.accessName);
 	            // if no relation from db column to prop name is found, assume that both are equal
-	            String propname = localrel == null ? prel.accessor : localrel.propName;
+	            String propname = localrel == null ? prel.accessName : localrel.propName;
 	            String prop = node.getString (propname);
 	            if (prop != null && prop.length() > 0) {
 	                INode old = getNode (prop);
@@ -932,7 +933,7 @@ public final class Node implements INode, Serializable {
 	    if (rel != null)
 	        return (IPathElement) getNode (name);
 	    rel = dbmap.getSubnodeRelation ();
-	    if (rel != null && rel.groupby == null && rel.accessor != null) {
+	    if (rel != null && rel.groupby == null && rel.accessName != null) {
 	        if (rel.otherType != null && rel.otherType.isRelational ())
 	            return (IPathElement) nmgr.getNode (this, name, rel);
 	        else
@@ -1112,10 +1113,10 @@ public final class Node implements INode, Serializable {
 	// check if subnodes are also accessed as properties. If so, also unset the property
 	if (dbmap != null && node.dbmap != null) {
 	    Relation prel = dbmap.getPropertyRelation();
-	    if (prel != null && prel.accessor != null) {
-	        Relation localrel = node.dbmap.columnNameToRelation (prel.accessor);
+	    if (prel != null && prel.accessName != null) {
+	        Relation localrel = node.dbmap.columnNameToRelation (prel.accessName);
 	        // if no relation from db column to prop name is found, assume that both are equal
-	        String propname = localrel == null ? prel.accessor : localrel.propName;
+	        String propname = localrel == null ? prel.accessName : localrel.propName;
 	        String prop = node.getString (propname);
 	        if (prop != null && getNode (prop) == node)
 	            unset (prop);
@@ -1309,17 +1310,13 @@ public final class Node implements INode, Serializable {
      */
     public Enumeration properties () {
 
-	if (dbmap != null && dbmap.isRelational() && dbmap.getProp2DB ().size() > 0)
+	if (dbmap != null && dbmap.isRelational())
 	    // return the properties defined in type.properties, if there are any
-	    return new Enumeration () {
-	        Iterator i = dbmap.getProp2DB().keySet().iterator();
-	        public boolean hasMoreElements() {return i.hasNext();}
-	        public Object nextElement () {return i.next();}
-	    };
+	    return dbmap.getPropertyEnumeration();
 
 	Relation prel = dbmap == null ? null : dbmap.getPropertyRelation ();
-	if (prel != null && prel.accessor != null && !prel.subnodesAreProperties
-			&& prel.otherType != null && prel.otherType.isRelational ())
+	if (prel != null && prel.hasAccessName()
+	                 && prel.otherType != null && prel.otherType.isRelational ())
 	    // return names of objects from a relational db table
 	    return nmgr.getPropertyNames (this, prel).elements ();
 	else if (propMap != null)
@@ -1493,7 +1490,7 @@ public final class Node implements INode, Serializable {
 	    propMap.put (p2, prop);
 	}
 
-	// check if this may have an effect on the node's URL when using subnodesAreProperties
+	// check if this may have an effect on the node's URL when using accessname
 	// but only do this if we already have a parent set, i.e. if we are already stored in the db
 	Node parent = parentHandle == null ? null : (Node) getParent ();
 
@@ -1504,7 +1501,7 @@ public final class Node implements INode, Serializable {
 	    Relation propRel = parentmap.getPropertyRelation ();
 	    String dbcolumn = dbmap.propertyToColumnName (propname);
 
-	    if (propRel != null && propRel.accessor != null && propRel.accessor.equals (dbcolumn)) {
+	    if (propRel != null && propRel.accessName != null && propRel.accessName.equals (dbcolumn)) {
 	        INode n = parent.getNode (value);
 	        if (n != null && n != this) {
 	            parent.unset (value);
@@ -1748,7 +1745,7 @@ public final class Node implements INode, Serializable {
 	    // UPDATE: using n.getKey() instead of manually constructing key. HW 2002/09/13
 	    tx.visitCleanNode (n.getKey(), n);
 	    // if the field is not the primary key of the property, also register it
-	    if (rel != null && rel.accessor != null && state != TRANSIENT) {
+	    if (rel != null && rel.accessName != null && state != TRANSIENT) {
 	        Key secKey = new SyntheticKey (getKey (), propname);
 	        nmgr.evictKey (secKey);
 	        tx.visitCleanNode (secKey, n);
diff --git a/src/helma/objectmodel/db/NodeManager.java b/src/helma/objectmodel/db/NodeManager.java
index e8c88b34..87134589 100644
--- a/src/helma/objectmodel/db/NodeManager.java
+++ b/src/helma/objectmodel/db/NodeManager.java
@@ -1027,8 +1027,8 @@ public final class NodeManager {
 	            }
 
 	            String accessProp = null;
-	            if (rel.accessor != null && !rel.usesPrimaryKey ())
-	                accessProp = dbm.columnNameToProperty (rel.accessor);
+	            if (rel.accessName != null && !rel.usesPrimaryKey ())
+	                accessProp = dbm.columnNameToProperty (rel.accessName);
 
 	            while (rs.next ()) {
 	                // create new Nodes.
@@ -1048,7 +1048,7 @@ public final class NodeManager {
 	                    sn.add (new NodeHandle (primKey));
 	                }
 
-	                // if relation doesn't use primary key as accessor, get accessor value
+	                // if relation doesn't use primary key as accessName, get accessName value
 	                String accessName = null;
 	                if (accessProp != null) {
 	                    accessName = node.getString (accessProp);
@@ -1166,7 +1166,7 @@ public final class NodeManager {
 	    Vector retval = new Vector ();
 	    // if we do a groupby query (creating an intermediate layer of groupby nodes),
 	    // retrieve the value of that field instead of the primary key
-	    String namefield = rel.accessor;
+	    String namefield = rel.accessName;
 	    Connection con = rel.otherType.getConnection ();
 	    String table = rel.otherType.getTableName ();
 
@@ -1296,7 +1296,7 @@ public final class NodeManager {
 	        if (home.getSubnodeRelation () != null) {
 	            // combine our key with the constraints in the manually set subnode relation
 	            q.append ("WHERE ");
-	            q.append (rel.accessor);
+	            q.append (rel.accessName);
 	            q.append (" = '");
 	            q.append (escape(kstr));
 	            q.append ("'");
diff --git a/src/helma/objectmodel/db/Property.java b/src/helma/objectmodel/db/Property.java
index d933c5b2..beabe7fa 100644
--- a/src/helma/objectmodel/db/Property.java
+++ b/src/helma/objectmodel/db/Property.java
@@ -238,7 +238,7 @@ public final class Property implements IProperty, Serializable, Cloneable {
 	// check if the property node is also a subnode
 	// BUG: this doesn't work because properties for subnode/properties are never stored and therefore
 	// never reused.
-	if (nvrel != null && nvrel.subnodesAreProperties) {
+	if (nvrel != null && nvrel.hasAccessName()) {
 	    node.removeNode (nvalue);
 	}
 	// only need to call unregisterPropLink if the value node is not stored in a relational db
diff --git a/src/helma/objectmodel/db/Relation.java b/src/helma/objectmodel/db/Relation.java
index c29a08c1..b744e588 100644
--- a/src/helma/objectmodel/db/Relation.java
+++ b/src/helma/objectmodel/db/Relation.java
@@ -52,10 +52,9 @@ public final class Relation {
     boolean readonly;
     boolean aggressiveLoading;
     boolean aggressiveCaching;
-    boolean subnodesAreProperties;
     boolean isPrivate;
 
-    String accessor; // db column used to access objects through this relation
+    String accessName; // db column used to access objects through this relation
     String order;
     String groupbyOrder;
     String groupby;
@@ -76,9 +75,8 @@ public final class Relation {
 	this.columnName = rel.columnName;
 	this.reftype = rel.reftype;
 	this.constraints = rel.constraints;
-	this.accessor = rel.accessor;
+	this.accessName = rel.accessName;
 	this.maxSize = rel.maxSize;
-	this.subnodesAreProperties = rel.subnodesAreProperties;
     }
 
     /**
@@ -199,10 +197,8 @@ public final class Relation {
 	    aggressiveLoading = aggressiveCaching = false;
 	}
 	// check if subnode condition should be applied for property relations
-	accessor = props.getProperty (propName+".accessname");
-	if (accessor != null)
-	    subnodesAreProperties = true;
-        // parse contstraints
+	accessName = props.getProperty (propName+".accessname");
+	// parse contstraints
 	String local = props.getProperty (propName+".local");
 	String foreign = props.getProperty (propName+".foreign");
 	if (local != null && foreign != null) {
@@ -257,7 +253,7 @@ public final class Relation {
      *  and never stored to a persistent storage.
      */
     public boolean createPropertyOnDemand () {
-	return virtual || accessor != null || groupby != null;
+	return virtual || accessName != null || groupby != null;
     }
 
     /**
@@ -321,13 +317,17 @@ public final class Relation {
 	    if (reftype == REFERENCE)
 	        return constraints.length == 1 && constraints[0].foreignKeyIsPrimary ();
 	    if (reftype == COLLECTION)
-	        return accessor == null || accessor.equalsIgnoreCase (otherType.getIDField ());
+	        return accessName == null || accessName.equalsIgnoreCase (otherType.getIDField ());
 	}
 	return false;
     }
 
-    public String getAccessor () {
-	return accessor;
+    public boolean hasAccessName () {
+	return accessName != null;
+    }
+
+    public String getAccessName () {
+	return accessName;
     }
 
     public Relation getSubnodeRelation () {
@@ -445,7 +445,7 @@ public final class Relation {
 	String prefix = pre;
 	if (kstr != null) {
 	    q.append (prefix);
-	    String accessColumn = accessor == null ? otherType.getIDField () : accessor;
+	    String accessColumn = accessName == null ? otherType.getIDField () : accessName;
 	    q.append (accessColumn);
 	    q.append (" = ");
 	    // check if column is string type and value needs to be quoted