Question

If you’ve a domain class in a grails project you can also use getter and setter to write or read them.

For example domain class Book has attribute:

String author

In controller you’ve a book and you want to set the author for this book:
This works with direct access to the attribute or with getter and setter methods although they aren’t in the class.

book.author = "Mike Miller"
book.setAuthor("Mike Miller")

What’s the preferred way of getting and setting attributes in groovy & grails?

Answer 1

They’re the same. When you have an unscoped field like String author, the Groovy compiler makes the field private and creates a getter and setter for it. It won’t overwrite existing methods though, so you can define your own set and/or get if it’s more than just setting and getting the value.

book.author = "Mike Miller" is Groovy syntactic sugar for calling the setter, just like String authorName = book.author is syntactic sugar for calling the getter. To see this, edit the class and add in a setter or getter and add a println, e.g.

void setAuthor(String a) {
   println "Setting author to '$a', was '$author'" 
   author = a
}

You can use a decompiler to see the generated code – I recommend JD-GUI, http://java.decompiler.free.fr/?q=jdgui