LazyInitializationException? Dá-lhe OpenEntityManagerInViewFilter

Quem nunca recebeu o "gratificante" erro LazyInitializationException?

org.hibernate.LazyInitializationException: failed to lazily initialize

Para resolvê-lo basta adicionar o filtro OpenEntityManagerInViewFilter no web.xml, que manterá o JPA EntityManager aberto por todo o request permitindo o lazy loading a partir da view.

<!-- web.xml -->
<filter>
    <filter-name>Spring OpenEntityManagerInViewFilter</filter-name>
    <filter-class>org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter</filter-class>
    <init-param>
        <param-name>singleSession</param-name>
        <param-value>true</param-value>
    </init-param>
</filter>
<filter-mapping>
    <filter-name>Spring OpenEntityManagerInViewFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>