Spring OpenSessionInViewFilter with @Transactional annotation

Question

This is regarding Spring OpenSessionInViewFilter using with @Transactional annotation at service layer.

i went through so many stack overflow post on this but still confused about whether i should use OpenSessionInViewFilter or not to avoid LazyInitializationException It would be great help if somebody help me find out answer to below queries.

• Is it bad practice to use OpenSessionInViewFilter in application having complex schema.
• using this filter can cause N+1 problem
• if we are using OpenSessionInViewFilter does it mean @Transactional not required?

Below is my Spring config file

<context:component-scan base-package="com.test"/>
<context:annotation-config/>
 <bean id="messageSource"
        class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
        <property name="basename" value="resources/messages" />
        <property name="defaultEncoding" value="UTF-8" />
    </bean>
 <bean id="propertyConfigurer"
        class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"
        p:location="/WEB-INF/jdbc.properties" />
 <bean id="dataSource"
        class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close"
        p:driverClassName="${jdbc.driverClassName}"
        p:url="${jdbc.databaseurl}" p:username="${jdbc.username}"
        p:password="${jdbc.password}" />
       <bean id="sessionFactory"
        class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />     
        <property name="configLocation">
            <value>classpath:hibernate.cfg.xml</value>
        </property>
        <property name="configurationClass">
            <value>org.hibernate.cfg.AnnotationConfiguration</value>
        </property>
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">${jdbc.dialect}</prop>
                <prop key="hibernate.show_sql">true</prop>
                <!--
                <prop key="hibernate.hbm2ddl.auto">create</prop>
                 -->
            </props>
        </property>
    </bean>
 <tx:annotation-driven /> 
 <bean id="transactionManager"
        class="org.springframework.orm.hibernate3.HibernateTransactionManager">
        <property name="sessionFactory" ref="sessionFactory" />

  </bean>

Answer 1

Throwing in my 0.02c here (and expanding on Fernando Rincon's excellent answer):

You shouldn't be using a OpenSessionInView filter just because you need to get around a LazyInitializationException. Its just going to add another layer of confusion and complexity to your system. You should know from your system design exactly where you are going to need to access collections on the front end. From there, it's easy and (in my experience) more logical to build a controller method to call a service method to retrieve your collection.

However if you have another problem that using the OpenSessionInView filter solves, and as a happy side effect you then have a session open, then I don't see the harm in using it to access your collections. However, I'd say that if you use the OpenSessionInView to fetch a collection object in one place, you should refactor your code in other places to do the same thing so as the strategy used to fetch collections is standardised across your application.

Weigh up the costs of this refactor against the cost of writing the controller & service methods to determine if you should be using a OpenSessionInView filter.