Hibernate magic with lazy evaluation

I’ve just run across this phenomenon for the first time and it turns out that hibernate can be even lazier than I thought! To illustrate lets use this time-honoured example in Grails.

Here are our domain objects:

class Book {  
    String title  
    static belongsTo = [author : Author]  
    static constraints = {  
    }  
}  
class Author {  
    String name  
    static hasMany = [books : Book]  
    static constraints = {  
    }  
}

and we’ll add some sample data in our bootstrap.groovy:

def init = { servletContext ->  
    def alice = new Author(name: 'alice').save()  
    def book1 = new Book(title: 'book1')  
    def book2 = new Book(title: 'book2')  
    alice.addToBooks(book1)  
    alice.addToBooks(book2)  
}

Now we’ll ...

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