Re: XPath Search

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

excellent...    very thorough!  Now, my only question is...    once I have =
a
list of all the features that match a particular phrase, along with keyword=
s
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 the axis
fcn's such as "parent::feature", to no avail.  I'm not even really sure wha=
t
the exact syntax is in order to get this to work anyway.  Can someone tell
me how to get the component element of the feature that matches.  Then 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 xm=
l
> file (each component has one keyword tag with multiple words) it works fi=
ne
> 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,'string'=
)],
> 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> o=
f
> the node in the node-set that is first in document order<http://www.w3.or=
g/TR/xpath#dt-document-order>.
> If the node-set is empty, an empty string is returned.".  And thus it wil=
l
> take the text 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 w=
e
> should find all features, and then go back up a level to get their owning
> components.  So we do:
>
> //feature[contains(.,'search string')]/..
>
> Nigel
>