[hibernate-dev] [Fwd: Re: no support for retrieving a native generated identifier using a custom user type]

From: Steve Ebersole <steve(a)hibernate.org&gt; To: Chris Webb <chris(a)hullomail.com&gt; Subject: Re: no support for retrieving a native generated identifier using a custom user type Date: Thu, 04 Dec 2008 16:30:12 -0600 The "more correct" solution is along the lines a contract to allow the type to handle this like you said. I'm thinking something like an optional interface for the type to publish that fact: public interface ResultSetIdentifierConsumer { public Serializable consumeIdentifier(ResultSet resultSet); } now IdentifierGeneratorFactory (called IdentifierGeneratorHelper now btw) can say: public static Serializable get(ResultSet rs, Type type) ... { if ( type instanceof ResultSetIdentifierConsumer ) { return ( ( ResultSetIdentifierConsumer ) type ).consumeIdentifier( rs ); } Class clazz = type.getReturnedClass(); if ( clazz == Long.class ) { return new Long( rs.getLong( 1 ) ); } else if ( clazz == Integer.class ) { return new Integer( rs.getInt( 1 ) ); } else if ( clazz == Short.class ) { return new Short( rs.getShort( 1 ) ); } else if ( clazz == String.class ) { return rs.getString( 1 ); } else { throw ... } } and you can define a type : public class VxsContactIdLongType ... implements ResultSetIdentifierConsumer ... { public Serializable consumeIdentifier(ResultSet resultSet) { return new VxsContactIdLong( resultSet.getLong( 1 ) ); } ... } -- Steve Ebersole Project Lead http://hibernate.org steve(a)hibernate.org Principal Software Engineer JBoss, a division of Red Hat http://jboss.com http://redhat.com steve.ebersole(a)jboss.com steve.ebersole(a)redhat.com On Thu, 2008-11-27 at 01:42 +0000, Chris Webb wrote: > Steve, > > I've come up with a generic solution that makes the slight assumption > that any custom user type identifier that supports native generation > provides an appropriate constructor to take in the returned result set > field. The constructor is called using reflection in > org.hibernate.id.IdentifierGeneratorFactory.get(ResultSet rs, Type > type) as follows: > > public static Serializable get(ResultSet rs, Type type) throws > SQLException, IdentifierGenerationException { > Class clazz = type.getReturnedClass(); > if ( clazz == Long.class ) { > return new Long( rs.getLong( 1 ) ); > } > else if ( clazz == Integer.class ) { > return new Integer( rs.getInt( 1 ) ); > } > else if ( clazz == Short.class ) { > return new Short( rs.getShort( 1 ) ); > } > else if ( clazz == String.class ) { > return rs.getString( 1 ); > } > else { > // >>>>>> START NEW LOGIC > > // Now check to see if the returned class wraps the > returned result > // set field. Assumes the returned class defines an > appropriate > // public constructor. > // TODO: Rather then assuming an appropriate constructor > and using > // reflection maybe the type should define a method that > takes a > // result set and returns the appropriate identifier type. > > Object identifierValue = null; > > try { > try { > Constructor<Serializable> constructor = > clazz.getConstructor(new Class[] { long.class}); > identifierValue = new Long(rs.getLong(1)); > return constructor.newInstance(new Object[] > { identifierValue }); > } catch (NoSuchMethodException e) { > try { > Constructor<Serializable> constructor = > clazz.getConstructor(new Class[] { int.class}); > identifierValue = new Integer(rs.getInt(1)); > return constructor.newInstance(new Object[] > { identifierValue }); > } catch (NoSuchMethodException e1) { > try { > Constructor<Serializable> constructor = > clazz.getConstructor(new Class[] { short.class}); > identifierValue = new > Short(rs.getShort(1)); > return constructor.newInstance(new > Object[] { identifierValue }); > } catch (NoSuchMethodException e2) { > try { > Constructor<Serializable> constructor > = clazz.getConstructor(new Class[] { String.class}); > identifierValue = rs.getString(1); > return constructor.newInstance(new > Object[] { identifierValue }); > } catch (NoSuchMethodException e3) { > // Do nothing. > } > } > } > } > } catch (SecurityException e) { > throw new IdentifierGenerationException("Failed to > instantiate identifier class '" + clazz + "' with identifier value '" > + identifierValue + "'", e); > } catch (IllegalArgumentException e) { > throw new IdentifierGenerationException("Failed to > instantiate identifier class '" + clazz + "' with identifier value '" > + identifierValue + "'", e); > } catch (InstantiationException e) { > throw new IdentifierGenerationException("Failed to > instantiate identifier class '" + clazz + "' with identifier value '" > + identifierValue + "'", e); > } catch (IllegalAccessException e) { > throw new IdentifierGenerationException("Failed to > instantiate identifier class '" + clazz + "' with identifier value '" > + identifierValue + "'", e); > } catch (InvocationTargetException e) { > throw new IdentifierGenerationException("Failed to > instantiate identifier class '" + clazz + "' with identifier value '" > + identifierValue + "'", e); > } > > // <<<<<< END NEW LOGIC > > throw new IdentifierGenerationException( "this id > generator generates long, integer, short or string or classes that > wrap those types" ); > } > > } > > I've left a comment in HB-92 to request the issue to be reopened and > the change described applied. Is the assumption I'm making acceptable? > Looking forward to hearing your comments. > > cheers, > chris > > > On Tue, Nov 11, 2008 at 3:52 PM, Chris Webb <chris(a)hullomail.com&gt; > wrote: > Steve, > > I hope you don't mind me approaching you directly with regard > to an issue I have. Please direct me to a more appropriate > channel if necessary. > > Back on the 21/05/03 I raised an issue (HB-92) to do with no > support for retrieving a native generated identifier using a > custom user type identifier. In a nutshell I had a custom user > type that wrapped a long and for all intensive acted like a > long but would not work with retrieving the native > auto-increment identifier because it wasn't exactly the Long > class. In Feb 2005 Gavin provided a solution regarding using a > PostInsertIdentifierGenerator but I didn't quite understand > how to utilise this. Now in 2008 I am revisiting this problem > and the issue seems to still exist with the original config. > > <class name="VxsContact" table="VXS_CONTACT"> > > <id name="id" column="CONTACT_ID" > type="com.voxsurf.pim.contacts.persistence.hibernate.VxsContactIdLongType"> > <generator class="native"/> > </id> > . > . > . > </class> > > The Hibernate code has moved on quite a bit since 2003 but > looking at the current GA release (v3.3.1) the problem seems > to be in > org.hibernate.id.IdentifierGeneratorFactory.get(ResultSet rs, > Type type). Despite the 'type' being passed into this method > the fact it may be a custom type is ignored and only types > that return Long, Integer, Short or String classes are > accepted. > > I have managed to hack the code to hardcode creating my custom > type if the relevant type is passed in to this method and this > appears to work. > > // unhappy about this being public ... is there a better > way? > public static Serializable get(ResultSet rs, Type type) > throws SQLException, IdentifierGenerationException { > // NOTE: This is a hack to return a specifc custom > type identifier. > if > (type.getReturnedClass().equals(VxsContactIdLong.class)) { > return new VxsContactIdLong(rs.getLong( 1 )); > } > > Class clazz = type.getReturnedClass(); > if ( clazz == Long.class ) { > return new Long( rs.getLong( 1 ) ); > } > else if ( clazz == Integer.class ) { > return new Integer( rs.getInt( 1 ) ); > } > else if ( clazz == Short.class ) { > return new Short( rs.getShort( 1 ) ); > } > else if ( clazz == String.class ) { > return rs.getString( 1 ); > } > else { > throw new IdentifierGenerationException( "this id > generator generates long, integer, short or string" ); > } > > } > > So the question is, could the 'type' passed in be used to > create the appropriate identifer type rather than only > supporting a fixed set of basic types. Looking at the TRUNK it > appears you have been making further changes to this area and > maybe this functionality has already been enabled. > > I have attached relevant classes. Let me know if you need any > further information. > > Look forward to hearing from you. > > Best regards, > Chris > > -- > Voicemail that's yours to keep! > Sign up @ www.hullomail.com > > Chris Webb > CTO > HulloMail Ltd > e) chris.webb(a)hullomail.com > m) +44 77 8639 2359