Spring Framework 3.0.5 - spring form data binding - comma delimiter - spring

Question

I have a group editation form:
<form:form method="POST" action="" commandName="group">
<table>
<tr>
<td><form:label path="name">Name</form:label></td>
<td><form:input path="name" disabled="disabled" /></td>
<td><form:errors path="name" class="error" /></td>
</tr>
<tr>
<td><form:label path="description">Description</form:label></td>
<td><form:input path="description" /></td>
<td><form:errors path="description" class="error" /></td>
</tr>
<tr>
<td><form:label path="gidNumber">GID</form:label></td>
<td><form:input path="gidNumber" /></td>
<td><form:errors path="gidNumber" class="error" /></td>
</tr>
<tr>
<td colspan="3"><input type="submit" /></td>
</tr>
</table>
<form:hidden path="members" />
</form:form>
This form is binding object of class Group. Problem is with binding the member attribute to the hidden field. The deffinition of the memeber attribute in Group class is below. The group class is also being used by Spring LDAP ODM manager, (thus the annotations there).
#Attribute(name="member", syntax="1.3.6.1.4.1.1466.115.121.1.12")
private List<String> members = new ArrayList<String>();
The content of this array list is usually something like:
1: uid=user1,ou=users,dc=example,dc=com
2: uid=lilcuttie2,ou=users,dc=example,dc=com
3: uid=naprostejmagor,ou=users,dc=example,dc=com
4: uid=crazyuser,ou=users,dc=brazzers,dc=com
...
When the content is binded to hidden field it is concatenated to the comma delimited and then when it is beeing splited again to the arraylist entries, of course each entry is broken to four separate entries.
I've tried to use custom converter for ArrayList, but it messed up some otheer stuf like loading resource messages for locales..
Do you have any suggestions how to deal with it in any non-ugly way - so that I dont have to wrap my DAO classes nor modify them.
Thanks,
/Jakub

Answer 1

Have a small wrapper type over your members element, say:
public class MembersWrapper{
private List<String> members;
.....
}
Now, you can provide a custom converter to convert this MembersWrapper instance to a String and back - the conversion can be to say colon delimited across each element of the list, something that you can parse back later:
public class MemberWrapperToStringConverter implements Converter<MemberWrapper, String>{
...
}
public class StringToMemberWrapperConverter implements Converter<String, MemberWrapper>{
....
}
and register these converters with Spring MVC:
<bean id="conversionService" class="org.springframework.format.support.FormattingConversionServiceFactoryBean">
<property name="converters">
<set>
<bean class="..MemberWrapperToStringConverter "/>
<bean class="..StringToMemberWrapperConverter "/>
</set>
</property>
</bean>
An alternative will be providing a custom property editor through #InitBinder annotation:
#InitBinder
public void initBinder(WebDataBinder binder){
binder.registerCustomEditor(Wrapper.class, new PropertyEditorSupport(){
#Override public String getAsText() {
//....
}
#Override public void setAsText(String text) throws IllegalArgumentException {
//....
}
});
}
The logic in these converters should be straightforward, convert the list to some string form, that you can parse back to list easily, say between list elements just add a colon or a semi-colon.

Answer 2

As I am not clear about your problem I have made some assumptions and providing this answer on basis of that.
Well you can use to loop your entries in the members list and for each entry in the list you can create a separate hidden field for that.
Hope this helps you.
Cheers.

Answer 3

You don't need to put the formtag for hidden field now when you are using just use the simple input tag for hidden fields but in the name property you need to specify as following.
<input type="hidden" name="members${status.index}"/>
in this way it will bind the same value back to the controller.
I think this should help you.
Cheers.