问题
What is the best way to handle multiple chackboxes when you nead to fill a JPA M:N relation ... for example I have an JPA entity Hardware and the entity Connectivity.
Hardware has a set for connectivity :
private Set<Connectivity> connectivities = new HashSet<Connectivity>(0);
and has a setter and getter like this :
@ManyToMany(fetch = FetchType.LAZY, cascade = { CascadeType.PERSIST, CascadeType.REFRESH }, mappedBy = "hwProviders")
public Set<Connectivity> getConnectivities() {
return this.connectivities;
}
public void setConnectivities(Set<Connectivity> connectivities) {
this.connectivities = connectivities;
}
I'm using JSF2.2 and primefaces 5.3 in the gui I have:
<p:selectManyCheckbox id="connectivity" value="#{hardware.connectivities}" converter="omnifaces.SelectItemsConverter" layout="pageDirection">
<f:selectItems value="#{connectivityes}" var="connect" itemValue="#{connect}" itemLabel="#{connect.name}"/>
</p:selectManyCheckbox>
I have problem with lazy exception even if I make a call to force load the set before rendering the view:
hardware.getConnectivities().size();
Any suggiestions on how to handle this situation?
I'm using omnifaces to make the entity conversion.
Tnx to BalusC I have managed to do the loading right but I still have problem wuth saving. When I select the checkbox and submit the form I get the lazy exception in conversion I think:
16:34:50,538 SEVERE [javax.enterprise.resource.webcontainer.jsf.context] (default task-12) org.hibernate.LazyInitializationException: failed to lazily initialize a collection, could not initialize proxy - no Session
at org.hibernate.collection.internal.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:575)
at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:214)
at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:554)
at org.hibernate.collection.internal.PersistentSet.add(PersistentSet.java:202)
at com.sun.faces.renderkit.html_basic.MenuRenderer.convertSelectManyValuesForModel(MenuRenderer.java:381)
at com.sun.faces.renderkit.html_basic.MenuRenderer.convertSelectManyValue(MenuRenderer.java:128)
at com.sun.faces.renderkit.html_basic.MenuRenderer.getConvertedValue(MenuRenderer.java:314)
at org.primefaces.component.selectmanycheckbox.SelectManyCheckboxRenderer.getConvertedValue(SelectManyCheckboxRenderer.java:39)
at javax.faces.component.UIInput.getConvertedValue(UIInput.java:1045)
at javax.faces.component.UIInput.validate(UIInput.java:975)
at javax.faces.component.UIInput.executeValidate(UIInput.java:1248)
at javax.faces.component.UIInput.processValidators(UIInput.java:712)
at javax.faces.component.UIForm.processValidators(UIForm.java:253)
at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1260)
at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1260)
at javax.faces.component.UIViewRoot.processValidators(UIViewRoot.java:1195)
at com.sun.faces.lifecycle.ProcessValidationsPhase.execute(ProcessValidationsPhase.java:76)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:198)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:646)
at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:130)
at si.arctur.filter.SessionFilter.doFilter(SessionFilter.java:76)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:60)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:132)
at io.undertow.servlet.handlers.FilterHandler.handleRequest(FilterHandler.java:85)
at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:61)
at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
at org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:131)
at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:56)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:45)
at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:63)
at io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:58)
at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:70)
at io.undertow.security.handlers.SecurityInitialHandler.handleRequest(SecurityInitialHandler.java:76)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:61)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:261)
at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:247)
at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:76)
at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:166)
at io.undertow.server.Connectors.executeRootHandler(Connectors.java:197)
at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:759)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
回答1:
You need to fetch it while inside a transaction (thus, inside the service method), and not while outside a transaction (thus, inside e.g. JSF managed bean init/action method), that would thus throw a LazyInitializationException.
So, your attempt
hardware.getConnectivities().size();
has to take place inside a transaction. Create if necessary a new service method for the purpose whereby you pass the entity which was obtained before in another transaction.
hardwareService.fetchConnectivities(hardware);
public void fetchConnectivities(Hardware hardware) {
hardware.setConnectivities(em.merge(hardware).getConnectivities()); // Becomes managed.
hardware.getConnectivities().size(); // Triggers lazy initialization.
}
An alternative would be to create a DTO for the purpose which has it eagerly fetched.
And then to save the selected items, make sure that you explicitly specify the selection component's collectionType attribute to a standard Java type rather than letting it autodiscover a JPA impl specific lazy loaded type such as org.hibernate.collection.internal.PersistentSet in your specific case. JSF needs it in order to instantiate the collection before filling it with the selected items.
<p:selectManyCheckbox ... collectionType="java.util.LinkedHashSet">
See also org.hibernate.LazyInitializationException at com.sun.faces.renderkit.html_basic.MenuRenderer.convertSelectManyValuesForModel.
回答2:
I fix it only by specifie
<f:attribute name="collectionType" value="java.util.LinkedHashSet" />
来源：https://stackoverflow.com/questions/30103161/lazyinitializationexception-in-selectmanycheckbox-on-manytomanyfetch-lazy