On 1/28/08, Stefan Behnel <[EMAIL PROTECTED]> wrote:
> Hi,
>
> Senthil Nathan wrote:
> > On 1/28/08, Stefan Behnel <[EMAIL PROTECTED]> wrote:
> >> Hi,
> >>
> >> Senthil Nathan wrote:
> >>> I would like to how to handle the xpath error gracefully when I use
> the
> >>> libxml api,
> >>> xmlXPathEvalExpression(path, xpathCtx).
> >>>
> >>> If I pass a invalid path string to evaluate on the "xpathCtx", it
> throws
> >> the
> >>> error as below and stops there.
> >>> But I would like to handle that error gracefully and log it
> accordingly
> >> and
> >>> proceed with my application.
> >> What is the reason why you cannot just continue after this error? Just
> >> call
> >> xmlXPathEvalExpression() again (with a working expression) and
> everything
> >> should be fine.
> >
> > In my application, when an invalid xpath string is given, during the
> > xmlXPathEvalExpression( ),
> > it fails with the error and just stops there. it's not continuing
> further
> > and just hangs or stops there.
> > So, I only need to break the application. Is there a better way to
> handle,
> > in case of these xpath errors.
>
> Ah, so it hangs *in* the eval call and does not return? I've never seen
> that
> before. And it definitely works for me in lxml (libxml2 2.6.31):
>
> >>> import lxml.etree as et
> >>> root = et.XML("<root/>")
> >>> root.xpath("/roottag///[EMAIL PROTECTED]'1']")
> Traceback (most recent call last):
> [...]
> lxml.etree.XPathEvalError: Invalid expression
> >>>
>
> That's basically using this code:
>
> xpathCtxt.node = some_node;
> xpathObj = xmlXPathEvalExpression(c_path, xpathCtxt);
I'm using the version 2.6.30 of libxml2
#define PACKAGE "libxml2"
#define VERSION "2.6.30"
The same way I also do it. But its only with my application which has
several threads, and when I give an invalid path, just hangs. Also the CPU
load is around 92% and keeps increasing further.
xmlXPathCtxPtr xpathCtx = xmlXPathNewContext(docTree);
xpathObj = xmlXPathEvalExpression(path, xpathCtx);
return(xpathObj->nodesetval);
Should I need to disable some flags. Because, in case of invalid expr, its
not returning from xmlXPathEvalExpression( ). If it's returns null, I can do
further processing. Or am I not handling it properly. I guess so.
> Could you supply the libxml2 version you are using and some example code
> that
> shows the problem? Does your machine show high CPU load while it hangs? (
> i.e.
> does it do something?)
>
> Stefan
>
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