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POIn Rails, how to respect :scope when using validates_uniqueness_of in an embedded object form?
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copied!<p>I have a Book model, which has_many Chapters (which belong_to a Book).</p> <p>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).</p> <p>Within the Chapter model:</p> <pre> validates_uniqueness_of( :chapter_title, :scope => :book_id, :case_sensitive => false, :message => "No book can have multiple chapters with the same title.") </pre> <p>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.</p> <pre><code>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 </code></pre> <p>Can anyone shed some light on how to do this? Or why it's happening?</p>

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