Jody: There is no way to map attribute values into seperate objects. One way to achieve this is to create use the Builder pattern to construct the desired objects. In your example, you would create an class that maps to the 'Command' tag, that has a 'Type" property. The code in this class would need to test the value of Type and construct the appropriate object. This may not be the optimal solution, but it should do the trick.
Tom Drake [EMAIL PROTECTED] ----- Original Message ----- From: "TERRILL,JODY (HP-Boise,ex1)" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Thursday, October 18, 2001 7:58 AM Subject: Re: [castor-dev] Un/Marshalling abstract objects | Next questions... :) | | Is there any way (short of using XSL translation) to unmarshal an object | based upon an Attribute? | Example: | <Command Type="Submit"/> | would create a submit object while | <Command Type="Query"/> | would create a query object. | | Is there anything that the XML Mapping file can do that can't be done with | the Descriptor framework in regards to un/marshalling? | | | Thanks in advance, | Jody Terrill | Hewlett-Packard | | > -----Original Message----- | > From: Keith Visco [mailto:[EMAIL PROTECTED]] | > Sent: Wednesday, October 17, 2001 2:54 PM | > To: [EMAIL PROTECTED] | > Subject: Re: [castor-dev] Un/Marshalling abstract objects | > | > | > | > | > Hi Jody, | > | > You should be able to do what you want with Castor. You can use a | > combination of compiled descriptors, mapping file, and default | > introspection. | > | > For example, if all the implementations of Message class are | > in the same | > package, including the Root class, Castor can automatically find these | > classes based on the element name. | > | > If you have an element named "command" then Castor will look | > for a class | > called Command.class | > | > The package that Castor looks in will be the package of the parent | > class...ie the Root.class. | > | > If you need to change this behavior you can always implement your own | > ClassDescriptorResolver. | > | > The default implementation is | > org.exolab.castor.xml.util.ClassDescriptorResolverImpl. | > | > Hope that helps, | > | > --Keith | > | > | > "TERRILL,JODY (HP-Boise,ex1)" wrote: | > > | > > Hello, | > > | > > I am looking at using Castor as a marshalling framework and | > have some | > > questions regarding how this might work with abstract java | > objects. I have | > > a java object model that allows a root object to contain one to many | > > abstract message objects. I'll try to simplify and | > summarize this below... | > > | > > public class Root{ | > > private java.util.ArrayList _messageList; // holds | > Message objects | > > } | > > | > > public abstract class Message; | > > public class Command extends Message; | > > public class Response extends Message; | > > | > > The XML instance can look like ... | > > | > > <Root> | > > <Command ID="3"/> | > > </Root> | > > or | > > <Root> | > > <Response ID="3"/> | > > </Root> | > > | > > I would like the Root class to only hold the abstract base | > class Message | > > (not Command and Response). Actually, in my problem there | > are potentially | > > >50 Message types. | > > | > > I think I can do the unmarshalling if I add an | > XMLFieldDescriptorImpl for | > > each possible Message type. What I think I would like is | > to write some code | > > that would generically create the object based upon it | > reflected name (e.g. | > > Command) and then checks to see if it is an instanceof | > Message. If it is, I | > > can add it to the _messagelist. This would allow others to | > extend the | > > framework without having to change the Root marshalling. | > > | > > For marshalling, what I think I need is a way for the | > framework to find the | > > proper descriptor to call instead of the abstract classes | > descriptor (e.g. | > > CommandDescriptor instead of MessageDescriptor). Is there | > a way for this to | > > happen or a way for the MessageDescriptor to figure the inheritance | > > heirarchy out and call the correct descriptor? | > > | > > I have primarily been working with the compile-time | > Descriptors. I briefly | > > looked at the mapping behaviour but I didn't see how it | > would help in this | > > situation and I would like the performance of the | > compile-time behaviour. | > > | > > Any insight into how this might be solved with Castor is | > appreciated. | > > | > > Thanks in advance, | > > Jody Terrill | > > Hewlett-Packard | > > | > > ----------------------------------------------------------- | > > If you wish to unsubscribe from this mailing, send mail to | > > [EMAIL PROTECTED] with a subject of: | > > unsubscribe castor-dev | > | > ----------------------------------------------------------- | > If you wish to unsubscribe from this mailing, send mail to | > [EMAIL PROTECTED] with a subject of: | > unsubscribe castor-dev | > | | ----------------------------------------------------------- | If you wish to unsubscribe from this mailing, send mail to | [EMAIL PROTECTED] with a subject of: | unsubscribe castor-dev | | | ----------------------------------------------------------- If you wish to unsubscribe from this mailing, send mail to [EMAIL PROTECTED] with a subject of: unsubscribe castor-dev
