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From Cheong Chung Onn <>
Subject Re: [Betwixt] Round tripping a Map object
Date Mon, 09 Feb 2004 03:49:42 GMT
Hi Robert,

Thanks for the reply.

I did anticipate that i might not be able to get a solution here and 
hence i came out with a cheap scheme to help solve my immediate 
problem, and this is what i have done. I have a Map object  as shown 

{ "service-name"="My Service",
   "service-provider"="A Complex Person Object"}

the above  Map object is converted to a XML Map object (all the values 
in this XML Map are either java primitive wrappers or a xml String that 
describe the complex object). Notice the  "service-provider" value in 
the above Map object is converted to a xml string using betwixt. The 
key of "service-provider" is appended with the Type of the complex 
object, this is to enable me to convert the xml back to an object. All 
the non-primitive java types (String, Integer, Boolean etc) will not be 
converted to any xml representation, all Java primitive wrappers will 
be left as is in the new XML Map object

{"service-name"="My Service",
""="<> A Complex Person 

All i need to do now is to serialize the Xml Map object for later use. 
To access the objects in the XML Map, i'll de-serialize the XML Map 
object and convert all the non-primitive Java types (Strings with 
<tags>) to object and place them in a new Map object.


On 9 Feb 04, at 5:49 AM, robert burrell donkin wrote:

> On 7 Feb 2004, at 11:09, Cheong Chung Onn wrote:
>> Hi all,
>> I sieved through the archive and found that a year ago, someone has 
>> asked a similar question. But the solution seems complicated, and now 
>> 1 year has past, i wonder if there is a more elegant way of solving 
>> the problem.
> i agree that the solution to maps is a little complicated and 
> inelegant and it would be great if better ways could be found. any new 
> ideas would be welcomed :)
>> Essentially, i have a Map object converted to xml in the form
>> ...
>> <entry>
>> 	<key> xxx</key>
>> 	<value>yyy</value>
>> </entry>
>> ...
>> The problem here is the "Type" info is missing for both <key> and 
>> <value>, is it possible now to provide a hint to Betwixt to enable it 
>> to do a round trip for a Map object. I am thinking that if i do have 
>> a table which maps the <key>s to <value>s Type and assuming all the 
>> <key> elements are String typed, can round tripping of a Map instance 
>> be done in a simple and straight forward manner?
>> <entry>
>> 	<key>aPerson</key>          <= aPerson - String type
>> 	<value>                                 <= Person.class
>> 		<person>
>> 			<name>John Doe</name>
>> 		</person>
>> 	</value>
>> </entry>
>> Any suggestion will be much appreciated. Thanks in advance.
> here's the way i see this problem...
> it's probably quite common that the key for a map will turn out to be 
> a simple value indexing a complex type.
> index: "AA11235"
> complex type: <person><name>John Doe</name>...</person>
> it seems to me that often a natural way to express this in xml would 
> be as an additional attribute so the resultant would be something 
> like:
> <person key='AA11235'><name>John Doe</name>...</person>
> (the key attribute may or may not exist on the actual object mapped).
> does this seem to ring true or are there other, more useful and common 
> strategies for mapping map entries that other people can think up?
> - robert
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