grails - Sorting on nullable fields in GORM -

i'm trying figure out how sort on multiple fields in grails 3, 1 of may or may not null. have book domain:

class book {      string title     string sorttitle      static constraints = {         title blank: false         sorttitle nullable: true     } } 

books titles "the peripheral" have sorttitle of "peripheral, the", otherwise sorttitle null. want books sorted sorttitle if 1 exists, otherwise title.

i found other similar questions, none nullable field. happen have pointers in right direction?

you can use:

coalesce(book.sorttitle, book.title)

here have official hibernate documentation.