X-Git-Url: https://git.pterodactylus.net/?a=blobdiff_plain;f=src%2Fmain%2Fjava%2Fnet%2Fpterodactylus%2Fdemoscenemusic%2Fdata%2FDataManager.java;h=962610029b9fff7b78c79dce986bc03a72f268c3;hb=f6ee754566a160171d611ba8b5151d71fa3ab4dc;hp=c87df731506efa288b689928be11bcd1eac8d485;hpb=2fd39b4383b041559364dce6eaf56c9164dbed82;p=demoscenemusic.git

diff --git a/src/main/java/net/pterodactylus/demoscenemusic/data/DataManager.java b/src/main/java/net/pterodactylus/demoscenemusic/data/DataManager.java
index c87df73..9626100 100644
--- a/src/main/java/net/pterodactylus/demoscenemusic/data/DataManager.java
+++ b/src/main/java/net/pterodactylus/demoscenemusic/data/DataManager.java
@@ -21,10 +21,12 @@ import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.util.Collection;
 import java.util.EnumMap;
+import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
+import java.util.Set;
 import java.util.UUID;
 import java.util.concurrent.Callable;
 
@@ -37,7 +39,9 @@ import net.pterodactylus.util.database.Join;
 import net.pterodactylus.util.database.Join.JoinType;
 import net.pterodactylus.util.database.ObjectCreator;
 import net.pterodactylus.util.database.ObjectCreator.StringCreator;
+import net.pterodactylus.util.database.OrWhereClause;
 import net.pterodactylus.util.database.OrderField;
+import net.pterodactylus.util.database.Parameter.IntegerParameter;
 import net.pterodactylus.util.database.Parameter.StringParameter;
 import net.pterodactylus.util.database.Query;
 import net.pterodactylus.util.database.Query.Type;
@@ -72,6 +76,10 @@ public class DataManager {
 	@SuppressWarnings("synthetic-access")
 	private final ObjectCreator<Style> styleCreator = new StyleCreator();
 
+	/** The party object creator. */
+	@SuppressWarnings("synthetic-access")
+	private final ObjectCreator<Party> partyCreator = new PartyCreator();
+
 	/** The {@link User} object creator. */
 	@SuppressWarnings("synthetic-access")
 	private final ObjectCreator<User> userCreator = new UserCreator();
@@ -185,6 +193,20 @@ public class DataManager {
 		query.addValueField(new ValueField("NAME", new StringParameter(artist.getName())));
 		query.addWhereClause(new ValueFieldWhereClause(new ValueField("ID", new StringParameter(artist.getId()))));
 		database.update(query);
+
+		/* save groups. */
+		Collection<Group> groups = artist.getGroups();
+		query = new Query(Type.DELETE, "GROUP_ARTISTS");
+		query.addWhereClause(new ValueFieldWhereClause(new ValueField("GROUP_ARTISTS.ARTIST", new StringParameter(artist.getId()))));
+		database.update(query);
+		for (Group group : groups) {
+			query = new Query(Type.INSERT, "GROUP_ARTISTS");
+			query.addValueField(new ValueField("GROUP_", new StringParameter(group.getId())));
+			query.addValueField(new ValueField("ARTIST", new StringParameter(artist.getId())));
+			database.insert(query);
+		}
+
+		/* save properties. */
 		saveArtistProperties(artist);
 	}
 
@@ -254,10 +276,7 @@ public class DataManager {
 	 *             if a database error occurs
 	 */
 	public List<Artist> loadArtistProperties(List<Artist> artists) throws DatabaseException {
-		for (Artist artist : artists) {
-			loadArtistProperties(artist);
-		}
-		return artists;
+		return loadProperties(artists, "ARTIST_PROPERTIES", "ARTIST");
 	}
 
 	/**
@@ -328,6 +347,24 @@ public class DataManager {
 	}
 
 	/**
+	 * Returns the track that contains the derivative with the given ID.
+	 *
+	 * @param id
+	 *            The ID of the track derivative
+	 * @return The track the derivative belongs to, or {@code null} if there is
+	 *         no such track
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public Track getTrackByDerivativeId(String id) throws DatabaseException {
+		Query query = new Query(Type.SELECT, "TRACKS");
+		query.addField(new Field("TRACKS.*"));
+		query.addJoin(new Join(JoinType.INNER, "TRACK_DERIVATIVES", new Field("TRACK_DERIVATIVES.TRACK"), new Field("TRACKS.ID")));
+		query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_DERIVATIVES.ID", new StringParameter(id))));
+		return loadTrackProperties(database.getSingle(query, trackCreator));
+	}
+
+	/**
 	 * Returns all tracks by the artist with the given ID.
 	 *
 	 * @param artistId
@@ -345,6 +382,23 @@ public class DataManager {
 	}
 
 	/**
+	 * Returns all tracks that were released at the party with the given ID.
+	 *
+	 * @param partyId
+	 *            The ID of the party
+	 * @return All tracks that were released at the given party
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public Collection<Track> getTracksByParty(String partyId) throws DatabaseException {
+		Query query = new Query(Type.SELECT, "TRACKS");
+		query.addField(new Field("TRACKS.*"));
+		query.addJoin(new Join(JoinType.INNER, "PARTY_TRACKS", new Field("PARTY_TRACKS.TRACK"), new Field("TRACKS.ID")));
+		query.addWhereClause(new ValueFieldWhereClause(new ValueField("PARTY_TRACKS.PARTY", new StringParameter(partyId))));
+		return loadTrackProperties(database.getMultiple(query, trackCreator));
+	}
+
+	/**
 	 * Loads the properties for the given track.
 	 *
 	 * @param track
@@ -367,10 +421,7 @@ public class DataManager {
 	 *             if a database error occurs
 	 */
 	public List<Track> loadTrackProperties(List<Track> tracks) throws DatabaseException {
-		for (Track track : tracks) {
-			loadTrackProperties(track);
-		}
-		return tracks;
+		return loadProperties(tracks, "TRACK_PROPERTIES", "TRACK");
 	}
 
 	/**
@@ -392,6 +443,49 @@ public class DataManager {
 	}
 
 	/**
+	 * Saves the given track. This also saves all relationships of the track.
+	 *
+	 * @param track
+	 *            The track to save
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public void saveTrack(Track track) throws DatabaseException {
+		Query query = new Query(Type.UPDATE, "TRACKS");
+		query.addValueField(new ValueField("TRACKS.NAME", new StringParameter(track.getName())));
+		query.addValueField(new ValueField("TRACKS.REMIX", new StringParameter(track.getRemix())));
+		query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACKS.ID", new StringParameter(track.getId()))));
+		database.update(query);
+		/* store artist information. */
+		track.getArtists(); /* prefetch artists. */
+		query = new Query(Type.DELETE, "TRACK_ARTISTS");
+		query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_ARTISTS.TRACK", new StringParameter(track.getId()))));
+		database.update(query);
+		for (int index = 0; index < track.getArtists().size(); ++index) {
+			query = new Query(Type.INSERT, "TRACK_ARTISTS");
+			query.addValueField(new ValueField("TRACK_ARTISTS.TRACK", new StringParameter(track.getId())));
+			query.addValueField(new ValueField("TRACK_ARTISTS.ARTIST", new StringParameter(track.getArtists().get(index).getId())));
+			query.addValueField(new ValueField("TRACK_ARTISTS.DISPLAY_ORDER", new IntegerParameter(index + 1)));
+			database.insert(query);
+		}
+
+		/* store party links. */
+		Collection<Party> parties = track.getParties(); /* prefetch parties. */
+		query = new Query(Type.DELETE, "PARTY_TRACKS");
+		query.addWhereClause(new ValueFieldWhereClause(new ValueField("PARTY_TRACKS.TRACK", new StringParameter(track.getId()))));
+		database.update(query);
+		for (Party party : parties) {
+			query = new Query(Type.INSERT, "PARTY_TRACKS");
+			query.addValueField(new ValueField("PARTY_TRACKS.TRACK", new StringParameter(track.getId())));
+			query.addValueField(new ValueField("PARTY_TRACKS.PARTY", new StringParameter(party.getId())));
+			database.insert(query);
+		}
+
+		/* store properties. */
+		saveProperties(track.getProperties(), "TRACK_PROPERTIES", "TRACK", track.getId());
+	}
+
+	/**
 	 * Returns the derivative with the given ID.
 	 *
 	 * @param id
@@ -410,16 +504,16 @@ public class DataManager {
 	/**
 	 * Returns the derivatives for the given track.
 	 *
-	 * @param track
-	 *            The track to get the derivatives for
+	 * @param trackId
+	 *            The track ID to get the derivatives for
 	 * @return The derivatives for the given track
 	 * @throws DatabaseException
 	 *             if a database error occurs
 	 */
-	public Collection<TrackDerivative> getTrackDerivativesByTrack(Track track) throws DatabaseException {
+	public Collection<TrackDerivative> getTrackDerivativesByTrack(String trackId) throws DatabaseException {
 		Query query = new Query(Type.SELECT, "TRACK_DERIVATIVES");
 		query.addField(new Field("TRACK_DERIVATIVES.*"));
-		query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_DERIVATIVES.TRACK", new StringParameter(track.getId()))));
+		query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_DERIVATIVES.TRACK", new StringParameter(trackId))));
 		return loadTrackDerivativeProperties(database.getMultiple(query, trackDerivativeCreator));
 	}
 
@@ -464,10 +558,67 @@ public class DataManager {
 	 *             if a database error occurs
 	 */
 	public List<TrackDerivative> loadTrackDerivativeProperties(List<TrackDerivative> trackDerivatives) throws DatabaseException {
-		for (TrackDerivative trackDerivative : trackDerivatives) {
-			loadTrackDerivativeProperties(trackDerivative);
-		}
-		return trackDerivatives;
+		return loadProperties(trackDerivatives, "TRACK_DERIVATIVE_PROPERTIES", "TRACK_DERIVATIVE");
+	}
+
+	/**
+	 * Saves the given track derivative. As a track derivative does not have any
+	 * attributes of its own only its properties are saved.
+	 *
+	 * @param trackDerivative
+	 *            The track derivative to save
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public void saveTrackDerivate(TrackDerivative trackDerivative) throws DatabaseException {
+		saveProperties(trackDerivative.getProperties(), "TRACK_DERIVATIVE_PROPERTIES", "TRACK_DERIVATIVE", trackDerivative.getId());
+	}
+
+	/**
+	 * Removes the given track derivative and all its properties from the
+	 * database.
+	 *
+	 * @param trackDerivative
+	 *            The track derivative to remove
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public void removeTrackDerivative(TrackDerivative trackDerivative) throws DatabaseException {
+		Query query = new Query(Type.DELETE, "TRACK_DERIVATIVES");
+		query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_DERIVATIVES.ID", new StringParameter(trackDerivative.getId()))));
+		database.update(query);
+		/* remove the properties. */
+		saveProperties(new Properties().set("dirty", "true").removeAll(), "TRACK_DERIVATIVE_PROPERTIES", "TRACK_DERIVATIVE", trackDerivative.getId());
+	}
+
+	/**
+	 * Returns all groups.
+	 *
+	 * @return All groups
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public Collection<Group> getAllGroups() throws DatabaseException {
+		Query query = new Query(Type.SELECT, "GROUPS");
+		query.addField(new Field("GROUPS.*"));
+		return loadGroupProperties(database.getMultiple(query, groupCreator));
+	}
+
+	/**
+	 * Returns the group with the given ID.
+	 *
+	 * @param groupId
+	 *            The ID of the group
+	 * @return The group with the given ID, or {@code null} if no such group
+	 *         exists
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public Group getGroupById(String groupId) throws DatabaseException {
+		Query query = new Query(Type.SELECT, "GROUPS");
+		query.addField(new Field("GROUPS.*"));
+		query.addWhereClause(new ValueFieldWhereClause(new ValueField("GROUPS.ID", new StringParameter(groupId))));
+		return loadGroupProperties(database.getSingle(query, groupCreator));
 	}
 
 	/**
@@ -488,6 +639,84 @@ public class DataManager {
 	}
 
 	/**
+	 * Loads the properties of the given group.
+	 *
+	 * @param group
+	 *            The group to load the properties for
+	 * @return The group with its properties loaded
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public Group loadGroupProperties(Group group) throws DatabaseException {
+		return loadProperties(group, "GROUP_PROPERTIES", "GROUP_ID");
+	}
+
+	/**
+	 * Loads the properties of the given groups.
+	 *
+	 * @param groups
+	 *            The groups to load the properties for
+	 * @return The groups with their properties loaded
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public Collection<Group> loadGroupProperties(List<Group> groups) throws DatabaseException {
+		return loadProperties(groups, "GROUP_PROPERTIES", "GROUP_ID");
+	}
+
+	/**
+	 * Creates a group with the given name.
+	 *
+	 * @param name
+	 *            The name of the new group
+	 * @param shortName
+	 *            The short name of the new group, or {@code null} if the group
+	 *            does not have a short name
+	 * @return The new group
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public Group createGroup(String name, String shortName) throws DatabaseException {
+		Query query = new Query(Type.INSERT, "GROUPS");
+		String id = UUID.randomUUID().toString();
+		query.addValueField(new ValueField("ID", new StringParameter(id)));
+		query.addValueField(new ValueField("NAME", new StringParameter(name)));
+		query.addValueField(new ValueField("SHORT_NAME", new StringParameter(shortName)));
+		database.insert(query);
+		return getGroupById(id);
+	}
+
+	/**
+	 * Saves the given group.
+	 *
+	 * @param group
+	 *            The group to save
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public void saveGroup(Group group) throws DatabaseException {
+		Query query = new Query(Type.UPDATE, "GROUPS");
+		query.addValueField(new ValueField("NAME", new StringParameter(group.getName())));
+		query.addValueField(new ValueField("SHORT_NAME", new StringParameter(group.getShortName())));
+		query.addWhereClause(new ValueFieldWhereClause(new ValueField("ID", new StringParameter(group.getId()))));
+		database.update(query);
+		/* save properties. */
+		saveGroupProperties(group);
+	}
+
+	/**
+	 * Saves the properties of the given group.
+	 *
+	 * @param group
+	 *            The group whose properties to save
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public void saveGroupProperties(Group group) throws DatabaseException {
+		saveProperties(group.getProperties(), "GROUP_PROPERTIES", "GROUP_ID", group.getId());
+	}
+
+	/**
 	 * Returns all styles for the track with the given ID.
 	 *
 	 * @param trackId
@@ -505,6 +734,124 @@ public class DataManager {
 	}
 
 	/**
+	 * Returns all parties.
+	 *
+	 * @return All parties
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public Collection<Party> getAllParties() throws DatabaseException {
+		Query query = new Query(Type.SELECT, "PARTIES");
+		query.addField(new Field("PARTIES.*"));
+		return loadPartyProperties(database.getMultiple(query, partyCreator));
+	}
+
+	/**
+	 * Returns all parties that the track with the given ID was released at.
+	 *
+	 * @param trackId
+	 *            The ID of the track
+	 * @return All parties the track was released at
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public Collection<Party> getPartiesByTrackId(String trackId) throws DatabaseException {
+		Query query = new Query(Type.SELECT, "PARTIES");
+		query.addField(new Field("PARTIES.*"));
+		query.addJoin(new Join(JoinType.INNER, "PARTY_TRACKS", new Field("PARTY_TRACKS.PARTY"), new Field("PARTIES.ID")));
+		query.addWhereClause(new ValueFieldWhereClause(new ValueField("PARTY_TRACKS.TRACK", new StringParameter(trackId))));
+		return loadPartyProperties(database.getMultiple(query, partyCreator));
+	}
+
+	/**
+	 * Returns the party with the given ID.
+	 *
+	 * @param partyId
+	 *            The ID of the party
+	 * @return The party with the given ID
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public Party getPartyById(String partyId) throws DatabaseException {
+		Query query = new Query(Type.SELECT, "PARTIES");
+		query.addField(new Field("PARTIES.*"));
+		query.addWhereClause(new ValueFieldWhereClause(new ValueField("PARTIES.ID", new StringParameter(partyId))));
+		return loadPartyProperties(database.getSingle(query, partyCreator));
+	}
+
+	/**
+	 * Loads the properties of the given party.
+	 *
+	 * @param party
+	 *            The party to load the properties for
+	 * @return The party with its properties loaded
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public Party loadPartyProperties(Party party) throws DatabaseException {
+		return loadProperties(party, "PARTY_PROPERTIES", "PARTY");
+	}
+
+	/**
+	 * Loads the properties of the given parties.
+	 *
+	 * @param parties
+	 *            The parties to load the properties for
+	 * @return The parties with their properties loaded
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public List<Party> loadPartyProperties(List<Party> parties) throws DatabaseException {
+		return loadProperties(parties, "PARTY_PROPERTIES", "PARTY");
+	}
+
+	/**
+	 * Saves the given party.
+	 *
+	 * @param party
+	 *            The party to save
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public void saveParty(Party party) throws DatabaseException {
+		Query query = new Query(Type.UPDATE, "PARTIES");
+		query.addValueField(new ValueField("NAME", new StringParameter(party.getName())));
+		query.addWhereClause(new ValueFieldWhereClause(new ValueField("ID", new StringParameter(party.getId()))));
+		database.update(query);
+		savePartyProperties(party);
+	}
+
+	/**
+	 * Saves the properties of the given party.
+	 *
+	 * @param party
+	 *            The party whose properties to save
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public void savePartyProperties(Party party) throws DatabaseException {
+		saveProperties(party.getProperties(), "PARTY_PROPERTIES", "PARTY", party.getId());
+	}
+
+	/**
+	 * Creates a new party with the given name.
+	 *
+	 * @param name
+	 *            The name of the party
+	 * @return The new party
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public Party createParty(String name) throws DatabaseException {
+		Query query = new Query(Type.INSERT, "PARTIES");
+		String id = UUID.randomUUID().toString();
+		query.addValueField(new ValueField("ID", new StringParameter(id)));
+		query.addValueField(new ValueField("NAME", new StringParameter(name)));
+		database.insert(query);
+		return getPartyById(id);
+	}
+
+	/**
 	 * Returns the user with the given name.
 	 *
 	 * @param username
@@ -574,6 +921,9 @@ public class DataManager {
 	 *             if a database error occurs
 	 */
 	private <T extends Base> T loadProperties(final T object, final String table, String type) throws DatabaseException {
+		if (object == null) {
+			return null;
+		}
 		Query query = new Query(Type.SELECT, table);
 		query.addField(new Field(table + ".PROPERTY"));
 		query.addField(new Field(table + ".VALUE"));
@@ -593,6 +943,56 @@ public class DataManager {
 	}
 
 	/**
+	 * Loads the properties for the given objects.
+	 *
+	 * @param <T>
+	 *            The type of the object
+	 * @param objects
+	 *            The objects
+	 * @param table
+	 *            The table to load the properties from
+	 * @param type
+	 *            The type of the object (“ARTIST,” “TRACK,” etc.)
+	 * @return The object with its properties loaded
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	private <T extends Base> List<T> loadProperties(List<T> objects, final String table, final String type) throws DatabaseException {
+		if (objects.isEmpty()) {
+			return objects;
+		}
+		final Map<String, T> objectMap = new HashMap<String, T>();
+		final Set<String> firstObjects = new HashSet<String>();
+		for (T object : objects) {
+			objectMap.put(object.getId(), object);
+			firstObjects.add(object.getId());
+		}
+		Query query = new Query(Type.SELECT, table);
+		query.addField(new Field(table + "." + type));
+		query.addField(new Field(table + ".PROPERTY"));
+		query.addField(new Field(table + ".VALUE"));
+		OrWhereClause whereClause = new OrWhereClause();
+		for (T object : objects) {
+			whereClause.add(new ValueFieldWhereClause(new ValueField(type, new StringParameter(object.getId()))));
+		}
+		query.addWhereClause(whereClause);
+		database.process(query, new ResultProcessor() {
+
+			@Override
+			public void processResult(ResultSet resultSet) throws SQLException {
+				String id = resultSet.getString(table + "." + type);
+				T object = objectMap.get(id);
+				if (firstObjects.remove(id)) {
+					object.getProperties().removeAll();
+				}
+				object.getProperties().set(resultSet.getString(table + ".PROPERTY"), resultSet.getString(table + ".VALUE"));
+			}
+
+		});
+		return objects;
+	}
+
+	/**
 	 * {@link Artist} implementation that retrieves some attributes (such as
 	 * {@link #getGroups()}, and {@link #getTracks()}) from the
 	 * {@link DataManager} on demand.
@@ -603,6 +1003,7 @@ public class DataManager {
 
 		/** Memoizer for the tracks by this artist. */
 		private final Memoizer<Void> tracksMemoizer = new Memoizer<Void>(new Callable<Void>() {
+
 			@Override
 			public Void call() throws DatabaseException {
 				if (!hasValue("tracks")) {
@@ -738,7 +1139,7 @@ public class DataManager {
 		 */
 		@Override
 		public Group createObject(ResultSet resultSet) throws SQLException {
-			return new LazyGroup(resultSet.getString("GROUPS.ID")).setName(resultSet.getString("GROUPS.NAME")).setUrl(resultSet.getString("GROUPS.URL"));
+			return new LazyGroup(resultSet.getString("GROUPS.ID")).setName(resultSet.getString("GROUPS.NAME")).setShortName(resultSet.getString("GROUPS.SHORT_NAME"));
 		}
 
 	}
@@ -797,7 +1198,7 @@ public class DataManager {
 			@Override
 			public Void call() throws Exception {
 				if (!hasValue("derivatives")) {
-					getValue("derivatives", Collection.class).set(getTrackDerivativesByTrack(LazyTrack.this));
+					getValue("derivatives", Collection.class).set(getTrackDerivativesByTrack(getId()));
 				}
 				return null;
 			}
@@ -814,6 +1215,7 @@ public class DataManager {
 				}
 				return null;
 			}
+
 		});
 
 		/**
@@ -875,6 +1277,21 @@ public class DataManager {
 			return super.getRelatedTracks();
 		}
 
+		/**
+		 * {@inheritDoc}
+		 */
+		@Override
+		public Collection<Party> getParties() {
+			if (!hasValue("parties")) {
+				try {
+					getValue("parties", Collection.class).set(getPartiesByTrackId(getId()));
+				} catch (DatabaseException de1) {
+					throw new RuntimeException("Could not load Parties for Track " + getId() + ".", de1);
+				}
+			}
+			return super.getParties();
+		}
+
 	}
 
 	/**
@@ -933,6 +1350,63 @@ public class DataManager {
 	}
 
 	/**
+	 * {@link Party} implementation that loads additional information only on
+	 * demand.
+	 *
+	 * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+	 */
+	private class LazyParty extends DefaultParty {
+
+		/**
+		 * Creates a new party.
+		 *
+		 * @param id
+		 *            The ID of the party
+		 */
+		public LazyParty(String id) {
+			super(id);
+		}
+
+		//
+		// PARTY METHODS
+		//
+
+		/**
+		 * {@inheritDoc}
+		 */
+		@Override
+		public Collection<Track> getReleases() {
+			if (!hasValue("releases")) {
+				try {
+					getValue("releases", Collection.class).set(getTracksByParty(getId()));
+				} catch (DatabaseException de1) {
+					throw new RuntimeException("Could not loaded Tracks for Party " + getId() + ".", de1);
+				}
+			}
+			return super.getReleases();
+		}
+
+	}
+
+	/**
+	 * {@link ObjectCreator} implementation that can create {@link Party}
+	 * objects.
+	 *
+	 * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+	 */
+	private class PartyCreator implements ObjectCreator<Party> {
+
+		/**
+		 * {@inheritDoc}
+		 */
+		@Override
+		public Party createObject(ResultSet resultSet) throws SQLException {
+			return new LazyParty(resultSet.getString("PARTIES.ID")).setName(resultSet.getString("PARTIES.NAME"));
+		}
+
+	}
+
+	/**
 	 * {@link User} implementation that retrieves some attributes (such as
 	 * {@link #getOpenIds()}) from the {@link DataManager} on demand.
 	 *