Re: Pharo-project Digest, Vol 27, Issue 118

On 19 July 2010 12:16,  <[hidden email]> wrote:
Hi Norbert:

Alas, I am laboring under the burden of being a newbie to both Pharo
and XML. It seems to me that it would be better to be able to
dynamically pick up all of the child elements of an element of
interest, however, I can't imagine how to define an object that
doesn't know it's own contents until run-time. In addition, in my
case, some of the child elements are complex (i.e. they also contain
children) which complicates the traversal a little bit. I'm assuming
for now that I will have to read the source XML, define the instance
variables of my object based on them, and simply populate them at run
time by traversing the XML tree. If the XML model changes, the object
definition will have to change too.

Thanks,
--
Larry Gadallah, VE6VQ/W7                          lgadallah AT gmail DOT com
PGP Sig: 917E DDB7 C911 9EC1 0CD9  C06B 06C4 835F 0BB8 7336

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On 20.07.2010, at 19:15, Larry Gadallah wrote:
Hi again,

just yesterday I discovered that I have a similar problem to solve. Usually I would try to solve it with magritte but this time I need some quick and dirty hack to achieve the goal. And somehow I like Pastell.

Let's take an XML Snippet

<Root>
        <Name>Mister RootNode</Name>
        <SubNode>
                <Name>Mister SubNode</Name>
        </SubNode>
</Root>

And now let's assume you want everything under Root in an object of class RootClass. In the case of SubNode you want a new object from class SubNodeClass that is referenced from RootClass object. In this example both classes RootClass and SubNodeClass are subclasses of NodeBaseClass

NodeBaseClass class>>node: aNode
        ^ self new
                node: aNode

NodeBaseClass>>node
        ^ node

NodeBaseClass>>node: aNode
        node := aNode

NodeBaseClass>>at: aSymbol
        ^ (self class xmodel at: aSymbol) value: self node

Here is the RootClass:

RootClass class>>xmodel
        ^ Dictionary new;
                at: #name put: [:node|  (node / #Name ) contentString  ];
                at: #subObject put: [:node| SubNodeClass node: (node / #SubNode) first ];
                yourself

and another class that is referenced from RootClass. Btw. "(node / #Name)" is using Pastell

SubNodeClass class>>xmodel
        ^ Dictionary new;
                at: #name put: [:node|  (node / #Name ) contentString  ];
                yourself


Then you could do:

document := XMLDOMParser parse....
rootObject := RootClass node: document root.
Transcript show: ((rootObject at: #subObject) at: #name

and you should get "Mister SubNode" . I hope there aren't too much errors in there. The basic idea is that every object gets an XML node and a description how to retrieve the values relative to this node. In the case of #name just a string is received. In the case of #subObject you can see how this gets recursive. #subObject returns itself an object that is just initialized with an XML node. Just like the rootObject

This is just a quick way to get some objects from an XML file. There is much room for improvement. I just wanted to give you an idea how you could solve it.

Hope this helps,

Norbert
 
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