X-Git-Url: https://git.pterodactylus.net/?a=blobdiff_plain;f=src%2Fmain%2Fjava%2Fnet%2Fpterodactylus%2Fdemoscenemusic%2Fdata%2FDataManager.java;h=5972bd882de240e4c4387b0a26f97fa1420dac19;hb=b2b9708445bf8b67def72383a63da3285c026339;hp=f936ff213b64034c7048dc92a87e8a69f8289478;hpb=552a91b0c8a42edf5e9288f333af9c2d1bbb8ec6;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 f936ff2..5972bd8 100644
--- a/src/main/java/net/pterodactylus/demoscenemusic/data/DataManager.java
+++ b/src/main/java/net/pterodactylus/demoscenemusic/data/DataManager.java
@@ -21,9 +21,13 @@ 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;
 
 import net.pterodactylus.demoscenemusic.data.Track.Relationship;
@@ -35,7 +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;
@@ -62,10 +68,18 @@ public class DataManager {
 	@SuppressWarnings("synthetic-access")
 	private final ObjectCreator<Track> trackCreator = new TrackCreator();
 
+	/** The track object creator. */
+	@SuppressWarnings("synthetic-access")
+	private final ObjectCreator<TrackDerivative> trackDerivativeCreator = new TrackDerivativeCreator();
+
 	/** The style object creator. */
 	@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();
@@ -93,7 +107,7 @@ public class DataManager {
 	public Collection<Artist> getAllArtists() throws DatabaseException {
 		Query query = new Query(Type.SELECT, "ARTISTS");
 		query.addField(new Field("ARTISTS.*"));
-		return database.getMultiple(query, artistCreator);
+		return loadArtistProperties(database.getMultiple(query, artistCreator));
 	}
 
 	/**
@@ -110,7 +124,7 @@ public class DataManager {
 		Query query = new Query(Type.SELECT, "ARTISTS");
 		query.addField(new Field("ARTISTS.*"));
 		query.addWhereClause(new ValueFieldWhereClause(new ValueField("ARTISTS.ID", new StringParameter(id))));
-		return database.getSingle(query, artistCreator);
+		return loadArtistProperties(database.getSingle(query, artistCreator));
 	}
 
 	/**
@@ -127,7 +141,7 @@ public class DataManager {
 		query.addField(new Field("ARTISTS.*"));
 		query.addJoin(new Join(JoinType.INNER, "GROUP_ARTISTS", new Field("ARTISTS.ID"), new Field("GROUP_ARTISTS.ARTIST")));
 		query.addWhereClause(new ValueFieldWhereClause(new ValueField("GROUP_ARTISTS.GROUP_", new StringParameter(groupId))));
-		return database.getMultiple(query, artistCreator);
+		return loadArtistProperties(database.getMultiple(query, artistCreator));
 	}
 
 	/**
@@ -145,7 +159,127 @@ public class DataManager {
 		query.addJoin(new Join(JoinType.INNER, "TRACK_ARTISTS", new Field("TRACK_ARTISTS.ARTIST"), new Field("ARTISTS.ID")));
 		query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_ARTISTS.TRACK", new StringParameter(trackId))));
 		query.addOrderField(new OrderField(new Field("TRACK_ARTISTS.DISPLAY_ORDER")));
-		return database.getMultiple(query, artistCreator);
+		return loadArtistProperties(database.getMultiple(query, artistCreator));
+	}
+
+	/**
+	 * Creates a new artist with the given name.
+	 *
+	 * @param name
+	 *            The name of the artist
+	 * @return The created artist
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public Artist createArtist(String name) throws DatabaseException {
+		Query query = new Query(Type.INSERT, "ARTISTS");
+		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 loadArtistProperties(getArtistById(id));
+	}
+
+	/**
+	 * Saves the given artist.
+	 *
+	 * @param artist
+	 *            The artist to save
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public void saveArtist(Artist artist) throws DatabaseException {
+		Query query = new Query(Type.UPDATE, "ARTISTS");
+		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);
+	}
+
+	/**
+	 * Saves the properties of the given artist.
+	 *
+	 * @param artist
+	 *            The artist whose properties to save
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public void saveArtistProperties(Artist artist) throws DatabaseException {
+		saveProperties(artist.getProperties(), "ARTIST_PROPERTIES", "ARTIST", artist.getId());
+	}
+
+	/**
+	 * Saves the given properties to the given table for the given principal.
+	 *
+	 * @param properties
+	 *            The properties to save
+	 * @param table
+	 *            The table in which to save the properties
+	 * @param type
+	 *            The type of the principal (e. g. “ARTIST” or “TRACK”)
+	 * @param id
+	 *            The ID of the principial
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public void saveProperties(Properties properties, String table, String type, String id) throws DatabaseException {
+		if (!properties.isDirty()) {
+			return;
+		}
+		Query query = new Query(Type.DELETE, table);
+		query.addWhereClause(new ValueFieldWhereClause(new ValueField(type, new StringParameter(id))));
+		database.update(query);
+		for (Entry<String, String> property : properties) {
+			Query insertQuery = new Query(Type.INSERT, table);
+			insertQuery.addValueField(new ValueField(type, new StringParameter(id)));
+			insertQuery.addValueField(new ValueField("PROPERTY", new StringParameter(property.getKey())));
+			insertQuery.addValueField(new ValueField("VALUE", new StringParameter(property.getValue())));
+			database.insert(insertQuery);
+		}
+		properties.resetDirty();
+	}
+
+	/**
+	 * Loads the properties for an artist.
+	 *
+	 * @param artist
+	 *            The artist to load the properties for
+	 * @return The artist
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public Artist loadArtistProperties(final Artist artist) throws DatabaseException {
+		return loadProperties(artist, "ARTIST_PROPERTIES", "ARTIST");
+	}
+
+	/**
+	 * Loads the properties of all given artists.
+	 *
+	 * @param artists
+	 *            The artists to load the properties for
+	 * @return The list of artists
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public List<Artist> loadArtistProperties(List<Artist> artists) throws DatabaseException {
+		for (Artist artist : artists) {
+			loadArtistProperties(artist);
+		}
+		return artists;
 	}
 
 	/**
@@ -212,7 +346,25 @@ public class DataManager {
 		Query query = new Query(Type.SELECT, "TRACKS");
 		query.addField(new Field("TRACKS.*"));
 		query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACKS.ID", new StringParameter(id))));
-		return database.getSingle(query, trackCreator);
+		return loadTrackProperties(database.getSingle(query, trackCreator));
+	}
+
+	/**
+	 * 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));
 	}
 
 	/**
@@ -229,7 +381,253 @@ public class DataManager {
 		query.addField(new Field("TRACKS.*"));
 		query.addJoin(new Join(JoinType.INNER, "TRACK_ARTISTS", new Field("TRACKS.ID"), new Field("TRACK_ARTISTS.TRACK")));
 		query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_ARTISTS.ARTIST", new StringParameter(artistId))));
-		return database.getMultiple(query, trackCreator);
+		return loadTrackProperties(database.getMultiple(query, trackCreator));
+	}
+
+	/**
+	 * 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
+	 *            The track for which to load the properties
+	 * @return The track with the properties loaded
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public Track loadTrackProperties(Track track) throws DatabaseException {
+		return loadProperties(track, "TRACK_PROPERTIES", "TRACK");
+	}
+
+	/**
+	 * Loads the properties for the given tracks.
+	 *
+	 * @param tracks
+	 *            The tracks for which to load the properties
+	 * @return The tracks with the properties loaded
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public List<Track> loadTrackProperties(List<Track> tracks) throws DatabaseException {
+		for (Track track : tracks) {
+			loadTrackProperties(track);
+		}
+		return tracks;
+	}
+
+	/**
+	 * Creates a new track with the given name.
+	 *
+	 * @param name
+	 *            The name of the track
+	 * @return The created track
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public Track createTrack(String name) throws DatabaseException {
+		Query query = new Query(Type.INSERT, "TRACKS");
+		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 getTrackById(id);
+	}
+
+	/**
+	 * 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
+	 *            The ID of the derivatives to load
+	 * @return The derivative with the given ID
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public TrackDerivative getTrackDerivativeById(String id) throws DatabaseException {
+		Query query = new Query(Type.SELECT, "TRACK_DERIVATIVES");
+		query.addField(new Field("TRACK_DERIVATIVES.*"));
+		query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_DERIVATIVES.ID", new StringParameter(id))));
+		return loadTrackDerivativeProperties(database.getSingle(query, trackDerivativeCreator));
+	}
+
+	/**
+	 * Returns the derivatives for the given track.
+	 *
+	 * @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(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(trackId))));
+		return loadTrackDerivativeProperties(database.getMultiple(query, trackDerivativeCreator));
+	}
+
+	/**
+	 * Creates a new derivative for the given track.
+	 *
+	 * @param track
+	 *            The track to create the derivative for
+	 * @return The created derivative
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public TrackDerivative createTrackDerivative(Track track) throws DatabaseException {
+		Query query = new Query(Type.INSERT, "TRACK_DERIVATIVES");
+		String id = UUID.randomUUID().toString();
+		query.addValueField(new ValueField("TRACK_DERIVATIVES.ID", new StringParameter(id)));
+		query.addValueField(new ValueField("TRACK_DERIVATIVES.TRACK", new StringParameter(track.getId())));
+		database.insert(query);
+		return getTrackDerivativeById(id);
+	}
+
+	/**
+	 * Loads the properties for the given track derivative.
+	 *
+	 * @param trackDerivative
+	 *            The track derivative to load the properties for
+	 * @return The track derivative with its properties loaded
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public TrackDerivative loadTrackDerivativeProperties(TrackDerivative trackDerivative) throws DatabaseException {
+		return loadProperties(trackDerivative, "TRACK_DERIVATIVE_PROPERTIES", "TRACK_DERIVATIVE");
+	}
+
+	/**
+	 * Loads the properties for the given track derivatives.
+	 *
+	 * @param trackDerivatives
+	 *            The track derivatives to load the properties for
+	 * @return The track derivatives with their properties loaded
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public List<TrackDerivative> loadTrackDerivativeProperties(List<TrackDerivative> trackDerivatives) throws DatabaseException {
+		for (TrackDerivative trackDerivative : trackDerivatives) {
+			loadTrackDerivativeProperties(trackDerivative);
+		}
+		return trackDerivatives;
+	}
+
+	/**
+	 * 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));
 	}
 
 	/**
@@ -250,6 +648,82 @@ 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(Collection<Group> groups) throws DatabaseException {
+		for (Group group : groups) {
+			loadGroupProperties(group);
+		}
+		return groups;
+	}
+
+	/**
+	 * Creates a group with the given name.
+	 *
+	 * @param name
+	 *            The name of the new group
+	 * @return The new group
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public Group createGroup(String name) 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)));
+		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.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
@@ -267,6 +741,143 @@ 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 {
+		for (Party party : parties) {
+			loadPartyProperties(party);
+		}
+		return parties;
+	}
+
+	/**
+	 * 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
+	 *            The name of the user
+	 * @return The user, or {@code null} if the user does not exist
+	 * @throws DatabaseException
+	 *             if a database error occurs
+	 */
+	public User getUserByName(String username) throws DatabaseException {
+		Query query = new Query(Type.SELECT, "USERS");
+		query.addField(new Field("USERS.*"));
+		query.addWhereClause(new ValueFieldWhereClause(new ValueField("USERS.NAME", new StringParameter(username))));
+		return database.getSingle(query, userCreator);
+	}
+
+	/**
 	 * Returns the user connected with the given OpenID.
 	 *
 	 * @param openId
@@ -300,6 +911,94 @@ public class DataManager {
 		return database.getMultiple(query, new StringCreator("USER_OPENIDS.OPENID"));
 	}
 
+	//
+	// PRIVATE METHODS
+	//
+
+	/**
+	 * Loads the properties for the given object.
+	 *
+	 * @param <T>
+	 *            The type of the object
+	 * @param object
+	 *            The object
+	 * @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> 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"));
+		query.addWhereClause(new ValueFieldWhereClause(new ValueField(type, new StringParameter(object.getId()))));
+		database.process(query, new ResultProcessor() {
+
+			@Override
+			public void processResult(ResultSet resultSet) throws SQLException {
+				if (resultSet.isFirst()) {
+					object.getProperties().removeAll();
+				}
+				object.getProperties().set(resultSet.getString(table + ".PROPERTY"), resultSet.getString(table + ".VALUE"));
+			}
+
+		});
+		return object;
+	}
+
+	/**
+	 * 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 {
+		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
@@ -311,6 +1010,7 @@ 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")) {
@@ -446,7 +1146,7 @@ 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"));
 		}
 
 	}
@@ -499,6 +1199,19 @@ public class DataManager {
 
 		});
 
+		/** Memoizer for the track derivatives. */
+		private final Memoizer<Void> derivativesMemoizer = new Memoizer<Void>(new Callable<Void>() {
+
+			@Override
+			public Void call() throws Exception {
+				if (!hasValue("derivatives")) {
+					getValue("derivatives", Collection.class).set(getTrackDerivativesByTrack(getId()));
+				}
+				return null;
+			}
+
+		});
+
 		/** Memoizer for the related tracks. */
 		private final Memoizer<Void> relatedTracksMemoizer = new Memoizer<Void>(new Callable<Void>() {
 
@@ -509,6 +1222,7 @@ public class DataManager {
 				}
 				return null;
 			}
+
 		});
 
 		/**
@@ -556,11 +1270,35 @@ public class DataManager {
 		 * {@inheritDoc}
 		 */
 		@Override
+		public Collection<TrackDerivative> getDerivatives() {
+			derivativesMemoizer.get();
+			return super.getDerivatives();
+		}
+
+		/**
+		 * {@inheritDoc}
+		 */
+		@Override
 		public Map<Relationship, Collection<Track>> getRelatedTracks() {
 			relatedTracksMemoizer.get();
 			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();
+		}
+
 	}
 
 	/**
@@ -583,6 +1321,24 @@ public class DataManager {
 	}
 
 	/**
+	 * {@link ObjectCreator} implementation that can create
+	 * {@link TrackDerivative} objects.
+	 *
+	 * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+	 */
+	private class TrackDerivativeCreator implements ObjectCreator<TrackDerivative> {
+
+		/**
+		 * {@inheritDoc}
+		 */
+		@Override
+		public TrackDerivative createObject(ResultSet resultSet) throws SQLException {
+			return new DefaultTrackDerivative(resultSet.getString("TRACK_DERIVATIVES.ID"));
+		}
+
+	}
+
+	/**
 	 * {@link ObjectCreator} implementation that can create {@link Style}
 	 * objects.
 	 *
@@ -601,6 +1357,63 @@ 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.
 	 *