# hasMany

## Purpose

Defines a one-to-many association between two classes.

## Examples

    class Author {
       String name
       static hasMany = [books:Book]
    }

In this example we define a one-to-many relationship between the `Author` class and the `Book` class (one `Author` has many books)

## Description

By default GORM will create a property of type `java.util.Set` using the key inside the definition of the `hasMany` map. For example consider this definition:

    static hasMany = [books:Book]

Here a property of type `java.util.Set` called `books` will be created within the defining class. These can then be iterated over and manipulated:

    def a = Author.get(1)
    a.books.each { println it.title }