Hi. I'm fairly new to Struts, but I've gone through the Struts documentation
and KeyboardMonkey's helpful tutorial. What I want to do is (almost) right
out of the tutorial, but it's not working the way I would expect.
The list archives show that other people have had this problem, and the few
real solutions I've found seem to indicate that I'm doing the right thing,
but I keep getting exceptions. My understanding is complicated by the fact
that the tutorial shows how to nest lists within a form, but I'm not using a
form (surely that's not necessary?).
One clarification I need: the KM tutorial indicates that only Object[] can
be used for nested lists, even though the Struts taglib docs say that
logic:iterate can iterate over Collection, Enumerations, arrays, etc. Is
that still true? Or can I nest lists where the bean property getters return
java.util.Collection?
So let me describe what I have, and what I'm trying to do. BTW, simply using
a single-level logic:iterate tag works great. I'm using Tomcat 4.0.4b2
and the nightly build of Struts from a couple days ago.
I have a set of Locations that are in a City. I have a list of Cities. I
would like to list all the Cities, and under each City list all the
locations. My code manages to list all the Cities, but when I add tags
HTML to list the Locations, I get variously tag nesting exceptions or null
pointer exceptions (and occasionally a getter not found exception),
depending on various ways of writing the code.
I have a City bean (called a Site for historical reasons, it will
eventually be changed) defined like this:
public class Site {
public StringgetCity() { return mCity; }
public voidsetCity(String inCity) { mCity = inCity; }
public StringgetState() { return mState; }
public voidsetState(String inState) { mState = inState; }
public CollectiongetLocations() { return mLocations; }
public voidsetLocations(Collection inLocations) { mLocations
= inLocations; }
private StringmCity = null;
privateStringmState = null;
privateCollectionmLocations = null; // Vector of Locations
}
and a FindResults bean defined like this:
public class FindResults {
public CollectiongetCities() { return mCities; }
public voidsetCities(Collection inCities) { mCities =
inCities; }
private CollectionmCities; // A Vector of Sites
}
There's also a simple Location bean:
public Location {
public String getName() { return mName; }
public void setName(String inName) { mName = inName; }
}
As a result of submitting a form, my FindAction object gets executed. It
takes the form input, does a JDBC lookup, then creates a FindResults bean
and puts it in the session state. The following (simplified) JSP displays
the list of cities satisfactorily:
%@ page contentType=text/html;charset=UTF-8 language=java %
%@ taglib uri=/WEB-INF/struts-bean.tld prefix=bean %
%@ taglib uri=/WEB-INF/struts-html.tld prefix=html %
%@ taglib uri=/WEB-INF/struts-logic.tld prefix=logic %
%@ taglib uri=/WEB-INF/struts-nested.tld prefix=nested %
jsp:useBean id=findResults scope=session
type=com.latencyzero.cc.FindResults/
head
titleSearch Results/title
/head
body bgcolor=#ff
logic:iterate id=foundCity name=findResults property=cities
table
trtd
Locations in bean:write name=foundCity property=city/
/td/tr
trtd
!-- insert location list here --
/td/tr
/table
/logic:iterate
/body
/html:html
It's when I try to nest a list that I run into trouble. I started by
replacing the insert location list here comment with the following:
logic:iterate id=foundLocation name=foundCity property=locations
pbean:write name=foundLocation property=name/p
/logic:iterate
As soon as I do that, I get org.apache.jasper.compiler.ParseException: End
of content reached while more parsing required: tag nesting error?.
Various permutations of using nested instead of logic and bean result
in other errors. For example, if I use nested:iterate for the inner loop
(and on the bean write), I get null pointer exception (even if I remove the
'name=foundCity' attribute).
I even tried to make a single outer loop (the very first example above) that
used a nested:write tag, just to see if I could get *something* nested
going. Using both logic:iterate and nested:iterate, this resulted in a
null pointer exception.
Clearly, I'm missing some fundamental point about nesting. Some people's
responses on the list indicate that they've had success simply nesting
logic:iterate tags without trouble
(http://www.mail-archive.com/struts-user@jakarta.apache.org/msg23493.html).
I'd be happy with that for this situation (I don't think I need the
implicit-dotting of hierarchies of properties for this simple operation).
TIA for any help!
BTW, is my approach of
