Grails, querying self-referencing table

Question

I have a table with a self-referencing field:

Class Book{

    Integer id
    String name
    Book version
}

When I add books without the "version", the version field is null now I have to query the Book table for records that don't have version (their version field is null), the following code won't work:

def results = Book.withCriteria{
    eq("version", "null")
} 

But I'm getting this exception:

org.hibernate.PropertyAccessException: IllegalArgumentException occurred calling getter of Book.id

what query should i use?

Answer 1

version is a keyword in GORM used for optimistic locking. Modify your domain and the criteria as below to make the criteria return appropriate results.

//Domain

class Book {
    Integer id
    String name
    Book bookVersion
}

//Criteria

def book = new Book(name: "test", version: null)
book.id = 1
book.save(flush: true)

def results = Book.withCriteria{
    isNull("bookVersion")
}

assert results && results[0] instanceof Book

Also note, bookVersion in the question is of type Book, it cannot be compared to String null.