Hello. Not sure if I'm addressing a known bug, but here it goes. I'm using Seam 2.0.0.GA, JBoss AS 4.2.2, JDK 1.5 I have a Many-to-Many mapping: Location entity: | private Collection<UserGroup> userGroups; | | @ManyToMany(TargetEntity=ro.ebsoft.doorcontrol.applogic.entity.UserGroup.class, | cascade={CascadeType.MERGE, CascadeType.PERSIST}) | @JoinTable(name="UserGroup_Location", | joinColumns={@JoinColumn(name="locationId")}, inverseJoinColumns={@JoinColumn(name="userGroupId")}) | public Collection<UserGroup> getUserGroups() { | return userGroups; | } | | public void setUserGroups(Collection<UserGroup> userGroups) { | this.userGroups = userGroups; | } | and UserGroup entity | private Collection<Location> locations = null; | | @ManyToMany( | cascade={CascadeType.PERSIST, CascadeType.MERGE}, | mappedBy="userGroups", | targetEntity=Location.class | ) | public Collection<Location> getLocations() { | return locations; | } | | public void setLocations(Collection<Location> locations) { | this.locations = locations; | } | | When adding a new UserGroup, a user can select any number of locations for the group. userGroup.xhtml : | <h:selectManyListbox id="locationsListBox" value="#{userGroupHome.instance.locations}" | disabled="#{not s:hasRole('admin')}"> | <s:convertEntity/> | <s:selectItems value="#{locationList.resultList}" var="location" label="#{location.locationName}"/> | </h:selectManyListbox> | When I try to save a new group (for instance, with the 2 top locations from the listbox), there's a failed validation. Faces Message: Conversion Error setting value '0 1' for '#{userGroupHome.instance.locations}'. I understand there's a problem binding a Set to a h:selectManyListBox (should use ArrayList). When trying to change Collection<Location> locations; to ArrayList<Location> locations; Hibernate notifies that it does not support it (mapping many to many to something else than a Collection). What to do? Does anyone have a fix for this problem? Thank you for your time. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4126217#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...