I can't fetch dom node in svg file with getElementById method(module minidom and libxml2dom)

[=?iso-8859-1?q?KLEIN_St=E9phane?=]

Hi,

I've a xml svg file and I would like to update it with Python.

First, I would like to fetch one dom node with getElementByID. I've one
issue about this method.

This is my example :

My SVG file :

"""
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!-- Created with Inkscape (http://www.inkscape.org/) -->
<svg:svg
xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns:cc="http://creativecommons.org/ns#"
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:svg="http://www.w3.org/2000/svg"
xmlns:xlink="http://www.w3.org/1999/xlink"
xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
width="210mm"
height="297mm"
id="svg2383"
sodipodi:version="0.32"
inkscape:version="0.46"
sodipodi:docname="product_page.svg"
inkscape:output_extension="org.inkscape.output.svg .inkscape">
</svg:svg>
"""

$ ipython

In [1]: from xml.dom import minidom

In [2]: dom1 = minidom.parse("myfile.svg")

In [3]: print(dom1.getElementById(u"svg2383"))
None

In [4]: print(dom1.getElementById("svg2383"))
None

I don't understand why getElementById return always None.

Other example with libxml2dom library :

$ ipython

In [1]: import libxml2dom

In [2]: dom2 = libxml2dom.parseFile("myfile.svg")

In [3]: print(dom2.getElementById(u"svg2383"))
None

In [4]: print(dom2.getElementById("svg2383"))

I don't understand why getElementById return always None.

Well, my final purpose isn't to fetch root dom node but to fetch many
other sub node.

Thanks for your informations.
Stephane

[Paul Boddie]

On 25 Aug, 11:43, KLEIN Stéphane <[e-mail]:

Hi,

I've a xml svg file and I would like to update it with Python.

First, I would like to fetch one dom node with getElementByID. I've one
issue about this method.

[SVG file with id attribute on svg element]

In [1]: from xml.dom import minidom

In [2]: dom1 = minidom.parse("myfile.svg")

In [3]: print(dom1.getElementById(u"svg2383"))
None

In [4]: print(dom1.getElementById("svg2383"))
None

I don't understand why getElementById return always None.

Here's a possible explanation:

http://www.w3.org/TR/DOM-Level-2-Cor...ml#ID-getElBId

"Attributes with the name "ID" are not of type ID unless so defined.
Implementations that do not know whether attributes are of type ID or
not are expected to return null."

Other example with libxml2dom library :

$ ipython

In [1]: import libxml2dom

In [2]: dom2 = libxml2dom.parseFile("myfile.svg")

In [3]: print(dom2.getElementById(u"svg2383"))
None

In [4]: print(dom2.getElementById("svg2383"))

I don't understand why getElementById return always None.

Here it's because I programmed it to do so. ;-) In fact, the
getElementById method provided by documents parsed by the
libxml2dom.svg module also return None in this case, although if I
were to take a look at the SVG DTD or schema, perhaps I should provide
such behaviour for SVG documents specifically.

Well, my final purpose isn't to fetch root dom node but to fetch many
other sub node.

You could always try using an XPath expression:

node = (dom2.xpath("//*[@id='svg2383']") or [None])[0]

Similar things could be done in PyXML and other libraries, I'm sure,
but minidom lacks XPath support, if I remember correctly.

Paul

P.S. There's so much I could be doing with libxml2dom, but we don't
all have enough time for everything we'd like to do (as I'm sure many
can understand). However, a Mercurial repository tracking the latest
work is available here:

https://hg.boddie.org.uk/libxml2dom

[=?iso-8859-1?q?KLEIN_St=E9phane?=]

Le Mon, 25 Aug 2008 04:30:00 -0700, Paul Boddie a écritÂ*:

>Well, my final purpose isn't to fetch root dom node but to fetch many
other sub node.

You could always try using an XPath expression:

node = (dom2.xpath("//*[@id='svg2383']") or [None])[0]

Similar things could be done in PyXML and other libraries, I'm sure, but
minidom lacks XPath support, if I remember correctly.

Thanks ! It work.

Regards,
Stephane