Module is.codion.framework.domain
Package is.codion.framework.domain.entity.condition

Interface ForeignKeyConditions

All Known Subinterfaces:
ForeignKey
public sealed interface ForeignKeyConditions permits ForeignKey (not exhaustive)
A ForeignKey based condition for filtering entities by their relationships.

ForeignKeyConditions enable querying entities based on their references to other entities. They provide type-safe filtering using entity instances or collections of entities, automatically handling primary key extraction and null value cases.

Foreign key conditions are typically created through the ForeignKeyConditions interface, which all ForeignKey instances implement: 

// Find albums by specific artist
Entity aliceInChains = connection.selectSingle(
				Artist.NAME.equalTo("Alice In Chains"));

List<Entity> aliceInChainsAlbums = connection.select(
				Album.ARTIST_FK.equalTo(aliceInChains));

// Find tracks by genre
Entity metal = connection.selectSingle(
				Genre.NAME.equalToIgnoreCase("metal"));

List<Entity> metalTracks = connection.select(
				Track.GENRE_FK.equalTo(metal));

// Find albums by multiple artists
List<Entity> theArtists = connection.select(
				Artist.NAME.like("The %"));

List<Entity> albumsByTheArtists = connection.select(
				Album.ARTIST_FK.in(theArtists));

// Find tracks without a genre
List<Entity> uncategorizedTracks = connection.select(
				Track.GENRE_FK.isNull());

// Find tracks with a genre
List<Entity> categorizedTracks = connection.select(
				Track.GENRE_FK.isNotNull());

// Complex query with foreign key conditions
List<Entity> albums = connection.select(and(
				Album.ARTIST_FK.in(theArtists),
				Album.ARTIST_FK.notEqualTo(excludedArtist)));

// Using with Select for more control
List<Entity> rockTracks = connection.select(
				Select.where(Track.GENRE_FK.equalTo(rock))
								.attributes(Track.NAME, Track.ALBUM_FK)
								.orderBy(ascending(Track.NAME)));

// Foreign key conditions with null handling
List<Entity> metalOrUncategorized = connection.select(or(
				Track.GENRE_FK.equalTo(metal),
				Track.GENRE_FK.isNull()));
See Also: