在grails中为hasMany字段设置XmlAttribute

class Book {
   static hasMany = [authors: Author]
   String title
   // 其他字段
}

class Author {
   String name
   // 其他字段
}

import grails.plugins.views.Xml

@Xml(root: "book")
class Book {
   static hasMany = [authors: Author]
   String title

   @XmlAttribute
   List<Author> authors = []
   // 其他字段
}

import grails.converters.XML

class BookController {
   def show() {
      def book = Book.get(params.id)
      render(contentType: "text/xml") {
         xml {
            book {
               title(book.title)
               authors {
                  book.authors.each { author ->
                     author(name: author.name)
                  }
               }
            }
         }
      }
   }
}

<book>
   <title>Book Title</title>
   <authors>
      <author name="Author 1" />
      <author name="Author 2" />
   </authors>
</book>