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displaying dom objects in Flex tree control from generated from java

Avatar

Level 1
I have written a POJO that returns hiearchial data from a
database in the form of a org.w3c.dom object. I have deployed this
object on my server and configured the remoting service. The remote
object is being invoked sucessfully. However I am not able to
populate the tree control with the dom object. The dom object is
generated according to the default data description as provided in
adobe manuals. Please help in advising how to populate the tree
control. The code is reproduced below.

---------------------------------------------------------------------------------------------------------

POJO Code for generating dom xml object

---------------------------------------------------------------------------------------------------------

package accounts.xmlconvert;



import java.sql.*;



import javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import javax.xml.parsers.ParserConfigurationException;



import org.w3c.dom.Document;

import org.w3c.dom.Element;

import org.w3c.dom.Text;





import
com.sun.org.apache.xml.internal.serialize.OutputFormat;

import
com.sun.org.apache.xml.internal.serialize.XMLSerializer;





public class XMLConvert {



public Document AccountService() throws Exception {



// String i="Null";

Document dom;

DocumentBuilderFactory dbf =
DocumentBuilderFactory.newInstance();

DocumentBuilder db = dbf.newDocumentBuilder();

dom = db.newDocument();



Element rootEle = dom.createElement("root");

dom.appendChild(rootEle);



//System.out.println(rootEle);






//------------------------------------------------------------------------------


Class.forName("org.postgresql.Driver");

String url = "jdbc:postgresql:postgres";



Connection con =
DriverManager.getConnection(url,"system","manager");



Statement stmt = con.createStatement();

ResultSet res = stmt.executeQuery("select * from accountlist
order by code");







while(res.next()) {



String code = res.getString(1);

String description = res.getString(2);

int parentcode = res.getInt(3);

String type = res.getString(4);





if(parentcode == 0) {



Element AccountListEle = dom.createElement("Groups");

AccountListEle.setAttribute("label",description);

AccountListEle.setAttribute("Id", code);

AccountListEle.setIdAttribute("Id",true);

rootEle.appendChild(AccountListEle);



}



if(parentcode > 0) {

if(type.equals("g")) {

//do something

PreparedStatement state = con.prepareStatement("select
code,description from accountlist where code = ?");

state.setInt(1,parentcode);



ResultSet result = state.executeQuery();



while(result.next()) {



Element foundParent =
dom.getElementById(result.getString(1));

Element newChild = dom.createElement("Groups");

newChild.setAttribute("label",description);

newChild.setAttribute("Id",code);

newChild.setIdAttribute("Id",true);

foundParent.appendChild(newChild);

}

result.close();

state.close();



}

if(type.equals("a")) {

//do something

PreparedStatement state = con.prepareStatement("select
code,description from accountlist where code = ?");

state.setInt(1,parentcode);



ResultSet result = state.executeQuery();



while(result.next()) {



Element foundParent =
dom.getElementById(result.getString(1));

Element newChild = dom.createElement("Account");

newChild.setAttribute("label",description);

newChild.setAttribute("Id",code);

newChild.setIdAttribute("Id",true);

foundParent.appendChild(newChild);

}

result.close();

state.close();





}





}





}




//------------------------------------------------------------------------------

/* //print

OutputFormat format = new OutputFormat(dom);

format.setIndenting(true);



//to generate output to console use this serializer

XMLSerializer serializer = new XMLSerializer(System.out,
format);

serializer.serialize(dom); */





res.close();



stmt.close();



con.close();



return dom;



}

}





---------------------------------------------------------------------------------------

the mxml application code

---------------------------------------------------------------------------------------



<?xml version="1.0"?>

<mx:Application xmlns:mx="
http://www.adobe.com/2006/mxml">



<mx:RemoteObject id="xmlconv"
destination="convertxml"/>



<mx:XMLListCollection id="capitalColl"
source="{xmlconv.AccountService.lastResult}"/>



<!-- The XMLListCollection does not include the XML root.
-->

<mx:Tree id="Tree2" dataProvider="{capitalColl}"
labelField="@label"

width="300"/>

<mx:Button click="xmlconv.AccountService()"/>



</mx:Application>



-------------------------------------------------------------------------------------------------------

Destination config

-------------------------------------------------------------------------------------------------------

<destination id="convertxml">

<properties>

<source>accounts.xmlconvert.XMLConvert</source>



</properties>

</destination>



------------------------------------------------------------------------------------------------------

i get this error when i click the button

------------------------------------------------------------------------------------------------------



[RPC Fault faultString="java.lang.NullPointerException :
null" faultCode="Server.Processing" faultDetail="null"]

at mx.rpc::AbstractInvoker/
http://www.adobe.com/2006/flex/mx/internal::faultHandler()

at mx.rpc::Responder/fault()

at mx.rpc::AsyncRequest/fault()

at
::NetConnectionMessageResponder/NetConnectionChannel.as$37:NetConnectionMessageResponder::statusHandler()

at mx.messaging::MessageResponder/status()



------------------------------------------------------------------------------------------------------------------------------------

if you are interested you may create a table in your database
and execute the following sql statements (this has been created in

postgresql 8.1)

-------------------------------------------------------------------------------------------------------------------------------------



create table accountlist ( code integer, description
varchar(64), parentcode integer, type character(1));



insert into table values (1,'Assets',0,'g');

insert into table values (2,'Liabilities',0,'g');

insert into table values (3,'Income',0,'g');

insert into table values (4,'Expenses',0,'g');

insert into table values (5,'Cash Balances',1,'g');

insert into table values (6,'Main Cash',5,'g');

insert into table values (7,'Share Capital',2,'g');

insert into table values (8,'BPO Services',3,'g');

insert into table values (9,'Software Development',3,'g');

insert into table values (10,'Other Income',3,'g');

insert into table values (11,'Sale of Old
Newspapers',10,'g');

insert into table values (12,'Sale of Scrap',10,'g');



------------------------------------------------------------------------------------------------------------------------

Please help with populating the tree control in flex.



Thanks in advance.



1 Reply

Avatar

Level 2
> [RPC Fault faultString="java.lang.NullPointerException :
null" faultCode="Server.Processing" faultDetail="null"]



The method in your remote object (XMLConvert) is throwing a
NullPointerException. Please debug the server-side code. Checking
the server logs for details or using a java debugger may help you
pinpoint the issue.