further cleaned up things around DbMapping and Relation - more to come

src/helma/objectmodel/DbMapping.java

@@ -37,11 +37,14 @@ public class DbMapping implements Updatable {
 
     ParentInfo[] parent;  // list of properties to try for parent
 
-    DbMapping subnodes;
+    // DbMapping subnodes;
-    DbMapping properties;
+    // DbMapping properties;
     Relation subnodesRel;
     Relation propertiesRel;
 
+    // if this defines a subnode mapping with groupby layer, we need a DbMapping for those groupby nodes
+    DbMapping groupbyMapping;
+
      // Map of property names to Relations objects
     Hashtable prop2db;
      // Map of db columns to Relations objects
@@ -88,8 +91,8 @@ public class DbMapping implements Updatable {
 	db2prop = new Hashtable ();
 
 	parent = null;
-	subnodes = null;
+	// subnodes = null;
-	properties = null;
+	// properties = null;
 	idField = "id";
     }
 
@@ -105,8 +108,8 @@ public class DbMapping implements Updatable {
 	db2prop = new Hashtable ();
 
 	parent = null;
-	subnodes = null;
+	// subnodes = null;
-	properties = null;
+	// properties = null;
 	idField = "id";
 
 	this.props = props;
@@ -191,9 +194,16 @@ public class DbMapping implements Updatable {
 	    try {
 	        if (!propName.startsWith ("_") && propName.indexOf (".") < 0) {
 	            String dbField = props.getProperty (propName);
-	            Relation rel = new Relation (dbField, propName, this, props);
+	            // check if a relation for this propery already exists. If so, reuse it
+	            Relation rel = propertyToRelation (propName);
+	            if (rel == null)
+	                rel = new Relation (dbField, propName, this, props);
+	            else
+	                rel.update (dbField, props);
 	            p2d.put (propName, rel);
-	            if (rel.localField != null)
+	            if (rel.localField != null &&
+	            		(rel.direction == Relation.PRIMITIVE ||
+	            		rel.direction == Relation.FORWARD))
 	                d2p.put (rel.localField, rel);
 	            // app.logEvent ("Mapping "+propName+" -> "+dbField);
 	        }
@@ -208,14 +218,18 @@ public class DbMapping implements Updatable {
 	String subnodeMapping = props.getProperty ("_subnodes");
 	if (subnodeMapping != null) {
 	    try {
-	        subnodesRel = new Relation (subnodeMapping, "_subnodes", this, props);
+	        // check if subnode relation already exists. If so, reuse it
-	        if (subnodesRel.isReference ())
+	        if (subnodesRel == null)
-	            subnodes = subnodesRel.other;
+	            subnodesRel = new Relation (subnodeMapping, "_subnodes", this, props);
 	        else
-	            subnodes = (DbMapping) app.getDbMapping (subnodeMapping);
+	            subnodesRel.update (subnodeMapping, props);
+	        // if (subnodesRel.isReference ())
+	            // subnodes = subnodesRel.other;
+	        // else
+	        //     subnodes = (DbMapping) app.getDbMapping (subnodeMapping);
 	    } catch (Exception x) {
-	        app.logEvent ("Error in type.properties: "+x.getMessage ());
+	        app.logEvent ("Error reading _subnodes relation for "+typename+": "+x.getMessage ());
-	        subnodesRel = null;
+	        // subnodesRel = null;
 	    }
 	} else
 	    subnodesRel = null;
@@ -223,22 +237,30 @@ public class DbMapping implements Updatable {
 	String propertiesMapping = props.getProperty ("_properties");
 	if (propertiesMapping != null) {
 	    try {
-	        propertiesRel = new Relation (propertiesMapping, "_properties", this, props);
+	        // check if property relation already exists. If so, reuse it
-	        if (propertiesRel.isReference ())
+	        if (propertiesRel == null)
-	            properties = propertiesRel.other;
+	            propertiesRel = new Relation (propertiesMapping, "_properties", this, props);
 	        else
-	            properties = (DbMapping) app.getDbMapping (propertiesMapping);
+	            propertiesRel.update (propertiesMapping, props);
+	        // if (propertiesRel.isReference ())
+	        //     properties = propertiesRel.other;
+	        // else
+	        //     properties = (DbMapping) app.getDbMapping (propertiesMapping);
 	        // take over groupby flag from subnodes, if properties are subnodes
 	        if (propertiesRel.subnodesAreProperties && subnodesRel != null)
 	            propertiesRel.groupby = subnodesRel.groupby;
 	    } catch (Exception x) {
-	        app.logEvent ("Error in type.properties: "+x.getMessage ());
+	        app.logEvent ("Error reading _properties relation for "+typename+": "+x.getMessage ());
-	        propertiesRel = null;
+	        // propertiesRel = null;
 	    }
 	} else
 	    propertiesRel = null;
 
-	// app.logEvent ("rewiring: "+this);
+	if (groupbyMapping != null) {
+	    groupbyMapping.subnodesRel = subnodesRel == null ? null : subnodesRel.getGroupbySubnodeRelation ();
+	    groupbyMapping.propertiesRel = propertiesRel == null ? null : propertiesRel.getGroupbyPropertyRelation ();
+	    groupbyMapping.lastTypeChange = this.lastTypeChange;
+	}
     }
 
 
@@ -323,21 +345,46 @@ public class DbMapping implements Updatable {
     /**
      * Translate a database column name to an object property name according to this mapping.
      */
-    public Relation columnNameToProperty (String columnName) {
+    public String columnNameToProperty (String columnName) {
 	if (table == null && parentMapping != null)
 	    return parentMapping.columnNameToProperty (columnName);
+	Relation rel = (Relation) db2prop.get (columnName);
+	if (rel != null  && (rel.direction == Relation.PRIMITIVE || rel.direction == Relation.FORWARD))
+	    return rel.propname;
+	return null;
+    }
+
+    /**
+     * Translate an object property name to a database column name according to this mapping.
+     */
+    public String propertyToColumnName (String propName) {
+	if (table == null && parentMapping != null)
+	    return parentMapping.propertyToColumnName (propName);
+	Relation rel = (Relation) prop2db.get (propName);
+	if (rel != null  && (rel.direction == Relation.PRIMITIVE || rel.direction == Relation.FORWARD))
+	    return rel.localField;
+	return null;
+    }
+
+    /**
+     * Translate a database column name to an object property name according to this mapping.
+     */
+    public Relation columnNameToRelation (String columnName) {
+	if (table == null && parentMapping != null)
+	    return parentMapping.columnNameToRelation (columnName);
 	return (Relation) db2prop.get (columnName);
     }
 
     /**
      * Translate an object property name to a database column name according to this mapping.
      */
-    public Relation propertyToColumnName (String propName) {
+    public Relation propertyToRelation (String propName) {
 	if (table == null && parentMapping != null)
-	    return parentMapping.propertyToColumnName (propName);
+	    return parentMapping.propertyToRelation (propName);
 	return (Relation) prop2db.get (propName);
     }
 
+
     public synchronized ParentInfo[] getParentInfo () {
     	if (parent == null && parentMapping != null)
     	    return parentMapping.getParentInfo ();
@@ -346,14 +393,13 @@ public class DbMapping implements Updatable {
 
 
     public DbMapping getSubnodeMapping () {
-    	if (subnodes == null && parentMapping != null)
+	if (subnodesRel != null)
+	    return subnodesRel.other;
+    	if (parentMapping != null)
     	    return parentMapping.getSubnodeMapping ();
-	return subnodes;
+	return null;
     }
 
-    public void setSubnodeMapping (DbMapping sm) {
-	subnodes = sm;
-    }
 
     public DbMapping getExactPropertyMapping (String propname) {
 	if (propname == null)
@@ -365,8 +411,13 @@ public class DbMapping implements Updatable {
     }
 
     public DbMapping getPropertyMapping (String propname) {
-	if (propname == null)
+	if (propname == null) {
-	    return properties;
+	    if (propertiesRel != null)
+	        return propertiesRel.other;
+	    if (parentMapping != null)
+	        return parentMapping.getPropertyMapping (null);
+	}
+	
 	Relation rel = (Relation) prop2db.get (propname.toLowerCase());
 	if (rel != null) {
 	    // if this is a virtual node, it doesn't have a dbmapping
@@ -376,16 +427,32 @@ public class DbMapping implements Updatable {
 	        return rel.other;
 	}
 	
-	if (properties == null && parentMapping != null)
+	if (propertiesRel != null)
+	    return propertiesRel.other;
+	if (parentMapping != null)
 	    return parentMapping.getPropertyMapping (propname);
-	
+	return null;
-	return properties;
     }
 
-    public void setPropertyMapping (DbMapping pm) {
+    public DbMapping getGroupbyMapping () {
-	properties = pm;
+	if (subnodesRel == null || subnodesRel.groupby == null)
+	    return null;
+	if (groupbyMapping == null) {
+	    groupbyMapping = new DbMapping ();
+	    groupbyMapping.subnodesRel = subnodesRel.getGroupbySubnodeRelation ();
+	    if (propertiesRel != null)
+	        groupbyMapping.propertiesRel = propertiesRel.getGroupbyPropertyRelation ();
+	    else
+	        groupbyMapping.propertiesRel = subnodesRel.getGroupbyPropertyRelation ();
+	    groupbyMapping.typename = subnodesRel.prototype;
+	}
+	return groupbyMapping;
     }
 
+    /* public void setPropertyMapping (DbMapping pm) {
+	properties = pm;
+    } */
+
     public void setSubnodeRelation (Relation rel) {
 	subnodesRel = rel;
     }

src/helma/objectmodel/DbSource.java

@@ -44,6 +44,15 @@ public class DbSource {
 	    // false here and make commit/rollback invocations in Transactor methods;
 	    IServer.getLogger().log ("Created new Connection to "+url);
 	    tx.registerConnection (this, con);
+	    //////////////////////////////////////////////
+	   /*  DatabaseMetaData meta = con.getMetaData ();
+	    ResultSet tables = meta.getCatalogs ();
+	    while (tables.next())
+	        System.err.println ("********* TABLE: "+ tables.getObject (1));
+	    ResultSet types = meta.getTypeInfo ();
+	    while (types.next())
+	        System.err.println ("******* TYPE: "+types.getObject(1) +" - "+types.getObject(2)+" - "+types.getObject(6));
+	    */
 	}
 	return con;
     }

src/helma/objectmodel/Node.java

@@ -393,9 +393,7 @@ public class Node implements INode, Serializable {
 	// node.setState (TRANSIENT);
 	// make a db mapping good enough that the virtual node finds its subnodes
 	DbMapping dbm = new DbMapping ();
-	dbm.setSubnodeMapping (rel.other);
 	dbm.setSubnodeRelation (rel);
-	dbm.setPropertyMapping (rel.other);
 	dbm.setPropertyRelation (rel);
 	node.setDbMapping (dbm);
 	setNode (propname, node);

src/helma/objectmodel/Relation.java

@@ -13,15 +13,27 @@ import java.util.Properties;
  */
 public class Relation {
 
-    // TODO: explain hop mapping types
+    // these constants define different type of property-to-db-mappings
+
+    // there is an error in the description of this relation
     public final static int INVALID = -1;
+     // a mapping of a non-object, scalar type
     public final static int PRIMITIVE = 0;
+     // a 1-to-1 relation, i.e. a field in the table is a foreign key to another object
     public final static int FORWARD = 1;
+    // a 1-to-many relation, a field in another table points to objects of this type
     public final static int BACKWARD = 2;
+    // direct mapping is a very powerful feature: objects of some types can be directly accessed
+    // by one of their properties/db fields.
     public final static int DIRECT = 3;
 
+    // the DbMapping of the type we come from
     public DbMapping home;
+    // the DbMapping of the prototype we link to, unless this is a "primitive" (non-object) relation
     public DbMapping other;
+    //  if this relation defines a virtual node, we need a DbMapping for these virtual nodes
+    DbMapping virtualMapping;
+
     public String propname;
     protected String localField, remoteField;
     public int direction;
@@ -34,31 +46,39 @@ public class Relation {
     public String order;
     public String groupbyorder;
     public String groupby;
+    public String dogroupby;
     public String prototype;
     public String groupbyprototype;
     public String filter;
 
-    Relation subnoderelation = null; // additional relation used to filter subnodes
+    Relation subnoderelation = null; // additional relation used to filter subnodes for virtual nodes
 
     /**
-     * This constructor is used to directly construct a Relation, as opposed to reading it from a proerty file
+     * This constructor makes a copy of an existing relation. Not all fields are copied, just those
+     * which are needed in groupby- and virtual nodes defined by this relation.
      */
-    public Relation (DbMapping other, String localField, String remoteField, int direction, boolean subnodesAreProperties) {
+    public Relation (Relation rel) {
-	this.other = other;
+	this.home = rel.home;
-	this.localField = localField;
+	this.other = rel.other;
-	this.remoteField = remoteField;
+	this.localField = rel.localField;
-	this.direction = direction;
+	this.remoteField = rel.remoteField;
-	this.subnodesAreProperties = subnodesAreProperties;
+	this.direction = rel.direction;
+	this.subnodesAreProperties = rel.subnodesAreProperties;
     }
 
     /**
      * Reads a relation entry from a line in a properties file.
      */
     public Relation (String desc, String propname, DbMapping home, Properties props) {
-
 	this.home = home;
 	this.propname = propname;
 	other = null;
+	
+	update (desc, props);
+    }
+
+    public void update (String desc, Properties props) {
+	
 	Application app = home.getApplication ();
 	boolean mountpoint = false;
 
@@ -179,6 +199,12 @@ public class Relation {
 	                subnoderelation.order = order;
 	            }
 	        }
+	        // update virtual mapping, if it already exists
+	        if (virtualMapping != null) {
+	            virtualMapping.subnodesRel = getVirtualSubnodeRelation ();
+	            virtualMapping.propertiesRel = getVirtualPropertyRelation ();
+	            virtualMapping.lastTypeChange = home.lastTypeChange;
+	        }
 	    }
 	}
     }
@@ -200,23 +226,6 @@ public class Relation {
 	return subnoderelation;
     }
 
-    /**
-     * Gets a key string to cache a node with a specific value for this relation. If the
-     * Relation uses the primary key return just the key value, otherwise include info on the
-     * used column or even the base node to avoid collisions.
-     */
-    /* public String getKeyID (INode home, String kval) {
-	// if the column is not the primary key, we add the column name to the key
-	if ((direction == DIRECT || direction == FORWARD) && !usesPrimaryKey ()) {
-	    // check if the subnode relation also has to be considered
-	    if (subnodesAreProperties)
-	        return "["+home.getID()+"]"+remoteField+"="+kval; // HACK
-	    else
-	        return remoteField+"="+kval;
-	} else {
-	    return kval;
-	}
-    } */
 
     /**
      * Get the local column name for this relation to use in where clauses of select statements.
@@ -247,18 +256,29 @@ public class Relation {
 	return remoteField;
     }
 
+    public DbMapping getVirtualMapping () {
+	if (!virtual)
+	    return null;
+	if (virtualMapping == null) {
+	    virtualMapping = new DbMapping ();
+	    virtualMapping.subnodesRel = getVirtualSubnodeRelation ();
+	    virtualMapping.propertiesRel = getVirtualPropertyRelation ();
+	}
+	return virtualMapping;
+    }
+
 
     /**
      * Return a Relation that defines the subnodes of a virtual node.
      */
-    public Relation getVirtualSubnodeRelation () {
+    Relation getVirtualSubnodeRelation () {
 	if (!virtual)
 	    throw new RuntimeException ("getVirtualSubnodeRelation called on non-virtual relation");
 	Relation vr = null;
 	if (subnoderelation != null)
-	    vr = subnoderelation.makeClone ();
+	    vr = new Relation (subnoderelation);
 	else
-	    vr = makeClone ();
+	    vr = new Relation (this);
 	vr.groupby = groupby;
 	vr.groupbyorder = groupbyorder;
 	vr.groupbyprototype = groupbyprototype;
@@ -273,10 +293,10 @@ public class Relation {
     /**
      * Return a Relation that defines the properties of a virtual node.
      */
-    public Relation getVirtualPropertyRelation () {
+    Relation getVirtualPropertyRelation () {
 	if (!virtual)
 	    throw new RuntimeException ("getVirtualPropertyRelation called on non-virtual relation");
-	Relation vr = makeClone ();
+	Relation vr = new Relation (this);
 	vr.groupby = groupby;
 	vr.groupbyorder = groupbyorder;
 	vr.groupbyprototype = groupbyprototype;
@@ -289,37 +309,35 @@ public class Relation {
     /**
      * Return a Relation that defines the subnodes of a group-by node.
      */
-    public Relation getGroupbySubnodeRelation () {
+    Relation getGroupbySubnodeRelation () {
 	if (groupby == null)
 	    throw new RuntimeException ("getGroupbySubnodeRelation called on non-group-by relation");
 	Relation vr = null;
 	if (subnoderelation != null)
-	    vr =  subnoderelation.makeClone ();
+	    vr =  new Relation (subnoderelation);
 	else
-	    vr =  makeClone ();
+	    vr =  new Relation (this);
 	vr.order = order;
 	vr.prototype = groupbyprototype;
 	vr.filter = filter;
+	vr.dogroupby = groupby;
 	return vr;
     }
 
     /**
      * Return a Relation that defines the properties of a group-by node.
      */
-    public Relation getGroupbyPropertyRelation () {
+    Relation getGroupbyPropertyRelation () {
 	if (groupby == null)
 	    throw new RuntimeException ("getGroupbyPropertyRelation called on non-group-by relation");
-	Relation vr = makeClone ();
+	Relation vr = new Relation (this);
 	vr.order = order;
 	vr.prototype = groupbyprototype;
 	vr.filter = filter;
+	vr.dogroupby = groupby;
 	return vr;
     }
 
-    public Relation makeClone () {
-	return new Relation (other, localField, remoteField, direction, subnodesAreProperties);
-    }
-
 
     public String toString () {
 	return "Relation["+home+">"+other+"]";