Find if added in domain class - not using findBy

Question

I have domain classes => many-to-many and associate them using addTo.

class Books {
    static belongsTo = Author
}

class Author {
    static belongsTo = Book
    static hasMany = [books: Book]
}

Controller:

author.addToBooks(mybook).save()

=> I want to check if mybook is already added to author. Is the a way to check if the book is already added to author (hopefully not using findBy)? Something like

if (author.isAdded(mybook))

Thanks.

score 6 · Accepted Answer · answered Jun 18 '12 at 18:53

By default defining as hasMany will use a java.util.Set. Since a Set is a collection that contains no duplicates, this means you can call author.addToBooks() with the same Book and it will not be added more than once - so it isn't necessary to check if a book is present.

However, to check for a Book in the Set, you can use author.books.contains(book)

Find if added in domain class - not using findBy

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