Re: XPath Search

[Tod M. <tod...@gm...>]

I'll try it out.  Thanks again!

Brad

On 2/10/06, Nigel Swinson <nig...@us...> wrote:
>
> Returns a list of features:
> //feature[contains(.,'search string')]
>
> Returns a list of components
> //feature[contains(.,'search string')]/..
>
> The trailing /.. is no accident.  It filters duplicates too
>
> Nigel
>
> ----- Original Message -----
> *From:* Tod McIntyre <tod...@gm...>
> *To:* Nigel Swinson <nig...@us...>
> *Cc:* php...@li...
> *Sent:* Friday, February 10, 2006 8:07 PM
> *Subject:* Re: XPath Search
>
> excellent...    very thorough!  Now, my only question is...    once I hav=
e
> a list of all the features that match a particular phrase, along with
> keywords etc.  I want to then get the component that that feature belongs
> to.  I'm not exactly sure how to get the parent.  I tried some of XPath t=
he
> axis fcn's such as "parent::feature", to no avail.  I'm not even really s=
ure
> what the exact syntax is in order to get this to work anyway.  Can someon=
e
> tell me how to get the component element of the feature that matches.  Th=
en
> all I need to do is eliminate duplicates and I'm set!
>
> Thanks again for all the help,
>
> Brad
>
> On 2/7/06, Nigel Swinson <nig...@us...> wrote:
> >
> > I've narrowed the problem down.  When I search through keywords in the
> > xml file (each component has one keyword tag with multiple words) it wo=
rks
> > fine using:
> > $components=3D$xPath->match("//component[contains(keyword,'string')]");
> > but when I search through features (each component has multiple
> > features) using:
> > $components=3D$xPath->match("//component[contains(feature,'string')]");
> > I get an empty array.
> >
> > Do I have to do something different if there are multiple tags such as
> > feature?
> >
> > Worked it out.  When you search for //component[contains(feature,'strin=
g')],
> > then it first of all evaluates //component to get a list of context
> > nodes, which will be something like:
> >
> > XPathSet:Array
> > (
> >     [0] =3D> /product[1]/component[1]
> >     [1] =3D> /product[1]/component[6]
> > )
> >
> > Then it filters the list based on the predicate, which is the
> > contains(feature,'string') bit.  But to do this, it needs to evaluate
> > the "feature" for each of the context nodes.  But for the first context=
 node
> > this returns something like:
> >
> > Array
> > (
> >     [0] =3D> /product[1]/component[1]/feature[1]
> >     [1] =3D> /product[1]/component[1]/feature[2]
> >     [2] =3D> /product[1]/component[1]/feature[3]
> >     [3] =3D> /product[1]/component[1]/feature[4]
> > )
> >
> > So the LHS is an array, and the RHS is a string.  According to
> > http://www.w3.org/TR/xpath#function-string, the contains function will
> > convert the LHS to a string by "A node-set is converted to a string by
> > returning the string-value <http://www.w3.org/TR/xpath#dt-string-value>=
of the node in the node-set that is first in document
> > order <http://www.w3.org/TR/xpath#dt-document-order> . If the node-set
> > is empty, an empty string is returned.".  And thus it will take the tex=
t
> > part of /product[1]/component[1]/feature[1], and ignore the rest.
> >
> > This explains why it works for the keyword, as you only have one
> > keyword.
> >
> > Instead of finding all components, and then filtering the list, instead
> > we should find all features, and then go back up a level to get their o=
wning
> > components.  So we do:
> >
> > //feature[contains(.,'search string')]/..
> >
> > Nigel
> >
>
>