Thanks guys, you answered all my questions :)
-----Original Message-----
From: Stephen Bash [mailto:[EMAIL PROTECTED]
Sent: Friday, July 08, 2005 8:18 AM
To: [email protected]
Subject: Re: [castor-user] How to map an List?
Keith-
Ah, it really does work :) This is one of those things I knew should
work, but had never worked for me... (shows how well digging through
someone else's code measures up to real experience)
Speaking of stuff like this, has anyone put together a "Castor Best
Practices" with common use cases? I know there are some examples in the
mapping documentation, and scattered through the list archive... (eek
-- that sounded dangerously close to volunteering!)
In any case, thanks for your help! It is very much appreciated.
Stephen
Keith Visco wrote:
>
> Stephen,
>
>
> Stephen Bash wrote:
>
>> Keith-
>>
>> Okay, after writing this whole e-mail, I think the short summary is I
>> don't know how to do two things:
>>
>> 1) Unmarshal a collection of mapped objects (no non-static
>> Unmarshaller methods accept a class argument)
>
>
> Unmarshaller unm = new Unmarshaller(ArrayList.class);
> unm.setMapping(mapping); ArrayList list = (ArrayList)
> unm.unmarshal(reader);
>
>>
>> 2) Customize the appearance/attributes of the root element when
>> marshaling a collection
>>
>
> Marshaller m = new Marshaller(myWriter); m.setMapping(mapping);
> m.setRootElement("foo"); m.marshal(list);
>
>
>
>> If there are quick answers to those two questions, feel free to skip
>> the rest of the e-mail :) Thanks!
>>
>
> Well the above should be good, but I'll keep reading :-)
>
>
>> More detailed e-mail follows:
>>
>> Hopefully Ali can fill you in on some more of the details, but I'll
>> include some quick work I've done and some problems I've run into.
>> Using this mapping file (referencing the class design in Ali's first
>> e-mail):
>>
>> <mapping>
>> <class name="castor.emami.one.Item">
>> <map-to xml="resource" />
>>
>> <field name="item" type="string">
>> <bind-xml name="item" node="attribute" />
>> </field>
>>
>> <field name="name" type="string">
>> <bind-xml name="name" node="attribute" />
>> </field>
>> </class>
>> </mapping>
>>
>> I get the following XML:
>>
>> <?xml version="1.0" encoding="UTF-8"?>
>> <array-list xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";>
>> <resource item="Item1" name="Test1" xsi:type="resource"/>
>> <resource item="Item2" name="Test2" xsi:type="resource"/>
>> <resource item="Item3" name="Test3" xsi:type="resource"/>
>> </array-list>
>>
>> From Ali's first e-mail, it appears he wants to rename the root
>> element, and he wants a "num-items" attribute in the root element.
>
>
> Well renaming the root can be done with the
Marshaller#setRootElement()
> method, adding the num-items attribute will have to be done with a
> mapping file...so in that case you'll have to create you own mapping
for
> java.util.ArrayList. Something like the following should work (though
I
> actually haven't tried it so it may need some tweaking) :
>
> <class name="java.util.ArrayList">
> <map-to xml="resources"/>
> <field name="items" type="java.lang.Object"
> collection="array" get-method="toArray" set-method="add">
> <bind-xml auto-naming="deriveByClass"/>
> </field>
> <field name="size" get-method="size">
> <bind-xml name="num-items" node="attribute"/>
> </field>
> </class>
>
>
>> Also on a side note, the xsi:type looks weird to me -- in this case
is
>> it redundant?
>>
>
> Yeah, I think the xsi:type is redundant here, but hopefully it doesn't
> hurt the unmarshalling process.
>
>> Then on unmarshalling, I want to specify the mapping file, but there
>> isn't a non-static method that can take in ArrayList.class as you
>> mention.
>>
>
> Well you can pass in the ArrayList in the constructor and then simply
> pass in the mapping file in the setMapping method. We should probably
> add a setRootClass(Class root) method to be consistent. When I
> originally wrote the Unmarshaller it was meant to know the root class
> ahread of time which is why it appears in the constructor. Only later
> did we add the support for searching the mapping file for the root
class
> based on the root element name.
>
> Hope that helps,
>
> --Keith
>
>
>
>
>> Any ideas? Thanks for the help!
>>
>> Stephen
>>
>> Keith Visco wrote:
>>
>>> Ali, Stephen,
>>>
>>> Can you guys re-summarize the problem for me as I'm not exactly sure
>>> what the issue is that you are having. I just marshalled an
ArrayList
>>> as the root element without any problems...unmarshalling also worked
>>> fine...just have to pass in ArrayList.class to the unmarshaller if
>>> xsi:type does not exist on the element.
>>>
>>>
>>> --Keith
>>>
>>>
>>>
>>> Stephen Bash wrote:
>>>
>>>> Ali-
>>>>
>>>> I have to admit, I have never found a good solution to this
>>>> problem. I almost always wrap the ArrayList inside another class,
>>>> at which point you can take advantage of the collection="arraylist"
>>>> attribute in a mapping file (and use nested class mappings if
>>>> necessary).
>>>>
>>>> One thought I do have, if (large caveat) you don't need to ever
>>>> unmarshall this list back into a Java object, is to list a field in
>>>> the mapping file (call it whatever) where you specify the
>>>> get-method="toArray", the type="Item", and the collection="array".
>>>> At that point Castor should recognize the Item class and use
>>>> whatever mapping you supply for it. Unfortunately, ArrayList
>>>> doesn't have a method "fromArray" or a constructor that takes in an
>>>> array in order to recreate the object, making this method unusable
>>>> for unmarshalling.
>>>>
>>>> One other possibility might be to use custom field handlers
>>>> (documentation on the Castor website), but I'm having a hard time
>>>> figuring out a slick way to approach the problem from that angle.
>>>>
>>>> Perhaps someone else can shed some more light on any of these
options.
>>>>
>>>> HTH,
>>>> Stephen
>>>>
>>>> Ali Emami wrote:
>>>>
>>>>> Hi everybody,
>>>>>
>>>>> Lets say that I have a ArrayList and I want to marshall it to a
xml
>>>>> file
>>>>> with a mapping file so I can get a result like this:
>>>>> <resources num-items= x >
>>>>> <resource id=1/>
>>>>> <resource id=2/>
>>>>> <resource id=3/>
>>>>> <resource id=4/>
>>>>> .
>>>>> .
>>>>>
>>>>> </resources>
>>>>> And lets say my object is something like this Public Class item {
>>>>> String item,
>>>>> String name,
>>>>>
>>>>> //Setters and getters
>>>>> }
>>>>>
>>>>> Is it possible to do this?
>>>>> I could get the num-items to work by doing something like this
>>>>>
>>>>> <class name="java.util.ArrayList" auto-complete="false">
>>>>> <map-to xml="resources"/>
>>>>> <field name="size" get-method="size">
>>>>> <bind-xml name="num-items" node="attribute"/>
>>>>> </field>
>>>>> .
>>>>> .
>>>>> .
>>>>>
>>>>>
>>>>> But I can not customize the object fields
>>>>> Thanks for your help
>>>>>
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