GrailsModelsPart2_2

Album.groovy

package recordstore

class Album {

	// Mappings
	static hasMany = [
		songs : Song 
	]
	
	
	// Properties
	String name
	List songs // ordered collection of songs
	
	static constraints = {
	}
}

BlogCategory.groovy

package blog

class BlogCategory {
	
	static hasMany = [
		entries : BlogEntries
	]	
	
	static mapping = {
		entries: sort:'dateCreated', order:'desc'
	}
}

songs_idx.text

mysql> select * from song;
+----+---------+----------+-------------+-----------+
| id | version | album_id | name        | songs_idx |
+----+---------+----------+-------------+-----------+
|  1 |       0 |        1 | Shame       |         0 |
|  2 |       0 |        1 | Die Die Die |         1 |
+----+---------+----------+-------------+-----------+
2 rows in set (0.00 sec)

songsWithinAnAlbumAreOrdered.groovy

@Test
void songsWithinAnAlbumAreOrdered() {
	def originalSongCount = Song.list().size()
	
	// Create and save an album
	def album = new Album( name: "Emotionalism" )
	def song = new Song( name: "Shame" )
	def song2 = new Song( name: "Die Die Die" )
	
	album.addToSongs( song )
	album.addToSongs( song2 )
	
	// Lists have an innate and reliable order
	def tmp = album.songs.get( 0 )
	album.songs[0] = album.songs[1]
	album.songs[1] = tmp
	
	assert album.songs[0] == song2
	assert album.songs[1] == song
	
}

weCanQueryForSongsViaFindersOrHQL.groovy

@Test
void weCanQueryForSongsViaFindersOrHQL() {
	// Create and save an album
	def album = new Album( name: "Emotionalism" )
	def song = new Song( name: "Die Die Die" )
	def song2 = new Song( name: "Shame" )
	
	album.addToSongs( song )
	album.addToSongs( song2 )
	album.save()
	
	// Dynamic finder
	assert Song.findAllByAlbum( album ).size() == 2
	
	// HQL
	assert Song.executeQuery( "from Song s where s.album = ?", [ album ] ).size() == 2
}