ANSWERS to "What's wrong with XQuery" question

[Brett Zamir]

  On 7/26/2010 5:18 PM, James Fuller wrote:
> Thx to Martin for the succinct overview of issues with XML<->JSON,
>
> I guess I am more leaning towards coming up with 'something different'
> ... maybe look at what serializing/dumping e4x internal representation
> is as I am assuming its a normal js object.
>
> I think if we get a serialization that maps directly onto a js object
> then we are done, e.g. we just need a representation that is
> consumable by javascript ... and I think e4x maybe the hook here.

E4X is only an extension to JavaScript, so it is only currently 
supported in Mozilla, and V8 (Chrome) is open to including it if a third 
party implements it: http://code.google.com/p/v8/issues/detail?id=235

E4X is treated as a fundamental type rather than as a regular object, 
with its own accessors which are JS object-like (and more powerful if 
filters are used, making it more XPath like).

For example,

var  friends=  <myData><friends>
<name  type="imaginary">Snuffaluffagus</name>
<name  type="real">Goober</name>
<name  type="imaginary">Tooth Fairy</name>
</friends></myData>;

var  realFriends=  friends..name.(@type==  'real').toString();  // Goober


You can also reshape data. If we just change the equality check to an 
assignment:

var  realFriends=  friends..name.(@type=  'real').toString();  // Goober


...we get as the results an "XMLList" (and the original element altered 
in place):

<name  type="real">Snuffaluffagus</name>
<name  type="real">Goober</name>
<name  type="real">Tooth Fairy</name>


To simulate some XQuery-like features, you might see 
https://developer.mozilla.org/en/E4X_for_templating , but E4X does not 
have a lot of built-in means of reshaping the XML other than as above or 
creating element names, attribute names, or attribute values and element 
content dynamically.

As far as serializing to more portable objects, there is a built-in 
method, "toXMLString()" for serializing the whole E4X object which 
represents the XML into a string (toString() will serialize the XML or 
return the text contents if the referenced element is only containing 
text). (Strings can in turn be converted to DOM objects or whatever.)

But there is no regular JSON traversal serialization.

Wonder if someone will make an E4X database that can also be XQueried... :)

Brett

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