CHAPTER 7: Rapid Web Development with Grails 351Now you can view the Book List by clicking the BookController link on the welcome screen, as
illustrated in Figure 7-35.
You can add a new book by clicking the New Book Link. When you click New Book, a Create Book
screen is displayed. If you try to create a book with blank Title and Isbn fields, you will get the validation
message illustrated in Figure 7 -3 6. You did not write any constraints for the ISBN in Listing 7-32, but still
there is validation on the ISBN field because Grails provides constraints by default for some fields, and
ISBN is one of them (as listed in Table 7-2 of this chapter).
Figure 7-35. Book List screen
Figure 7-36. Validation error