h:SelectManyListbox, s:SelectItems and Many-to-Many mapping

[ovistanciu]

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.

[pmuir]

Yes, you are right, you have to back a selectMany with a list or an array.

[ovistanciu]

Pete, I tried your example posted here: http://jroller.com/pmuir/entry/using_sets_in_jsf.
userGroup.xhtml now looks like this:

<h:selectManyListbox id="locationsListBox" value="#{dc:asList(userGroupHome.instance.locations)}"
 disabled="#{not s:hasRole('admin')}">
 <s:convertEntity />
 <s:selectItems value="#{locationList.resultList}" var="location"
 label="#{location.locationName}" noSelectionLabel="None" />
 </h:selectManyListbox>

where 'asList' is the function described in the link above.
Now, when trying to create a userGroup I get:

model validation failed:/members/userGroup.xhtml @33,44 value="#{dc:asList(userGroupHome.instance.locations)}": Illegal Syntax for Set Operation

What am I missing?

[pmuir]

Is there a stack trace for that?

[ovistanciu]

No, there isn't. Just the faces message posted above (model validation failed).

[stephendv]

I'm had similar problems getting this to work - eventually solved it, code is here: http://www.twisteddelight.org/downloads/contactn.tar.gz
Recipients have a many to many relationship with Profiles. I used a selectManyCheckbox to allow recipients to assign themselves to profiles.
AFAIK, selectManyListBox would be identical.