In Rails, how to respect :scope when using validates_uniqueness_of in an embedded object form?
- by mkirk
I have a Book model, which has_many Chapters (which belong_to a Book).
I want to ensure uniqueness of Chapter titles, but only within the scope of a single book. The catch is that the form for creating chapters is embedded in the Book model's form (The Book model accepts_nested_attributes_for :chapters).
Within the Chapter model:
validates_uniqueness_of(
:chapter_title,
:scope = :book_id,
:case_sensitive = false,
:message = "No book can have multiple chapters with the same title.")
However, when I submit the Book creation form (which also includes multiple embedded Chapter forms), if the chapter title exists in another chapter for a different book, I fail the validation test.
Book.create( :chapters => [ Chapter.new(:title => "Introduction"), Chapter.new(:title => "How to build things")
=> Book 1 successfully created
Book.create( :chapters => [ Chapter.new(:title => "Introduction"), Chapter.new(:title => "Destroy things")
=> Book 2 fails to validate
second_book = Book.create( :chapters => [ Chapter.new(:title => "A temporary Introduction title"), Chapter.new(:title => "Destroy things")
=> Book 2 succesfully created
second_book.chapters[0].title= "Introduction"
=> success
second_book.chapters.save
=> success
second_book.save
=> success
Can anyone shed some light on how to do this? Or why it's happening?
