XML en XPath
Wat is XPath?
XPath is 'n belangrike element in die XSLT-standaard.
XPath kan gebruik word om deur elemente en eienskappe in 'n XML-dokument te navigeer.
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XPath-paduitdrukkings
XPath gebruik paduitdrukkings om nodusse of nodusstelle in 'n XML-dokument te kies. Hierdie pad-uitdrukkings lyk baie soos die uitdrukkings wat jy sien wanneer jy met 'n tradisionele rekenaarlêerstelsel werk.
XPath uitdrukkings kan gebruik word in JavaScript, Java, XML Skema, PHP, Python, C en C++, en baie ander tale.
XPath word in XSLT gebruik
XPath is 'n belangrike element in die XSLT-standaard.
Met XPath-kennis sal jy groot voordeel uit XSL kan trek.
Voorbeeld van XPath
Ons sal die volgende XML-dokument gebruik:
<?xml version="1.0" encoding="UTF-8"?>
<bookstore>
<book category="cooking">
<title lang="en">Everyday Italian</title>
<author>Giada De Laurentiis</author>
<year>2005</year>
<price>30.00</price>
</book>
<book category="children">
<title lang="en">Harry Potter</title>
<author>J K. Rowling</author>
<year>2005</year>
<price>29.99</price>
</book>
<book category="web">
<title lang="en">XQuery Kick Start</title>
<author>James McGovern</author>
<author>Per Bothner</author>
<author>Kurt Cagle</author>
<author>James Linn</author>
<author>Vaidyanathan Nagarajan</author>
<year>2003</year>
<price>49.99</price>
</book>
<book category="web">
<title lang="en">Learning XML</title>
<author>Erik T. Ray</author>
<year>2003</year>
<price>39.95</price>
</book>
</bookstore>In die tabel hieronder het ons 'n paar XPath-uitdrukkings en die resultaat van die uitdrukkings gelys:
| XPath Expression | Result |
|---|---|
| /bookstore/book[1] | Selects the first book element that is the child of the bookstore element |
| /bookstore/book[last()] | Selects the last book element that is the child of the bookstore element |
| /bookstore/book[last()-1] | Selects the last but one book element that is the child of the bookstore element |
| /bookstore/book[position()<3] | Selects the first two book elements that are children of the bookstore element |
| //title[@lang] | Selects all the title elements that have an attribute named lang |
| //title[@lang='en'] | Selects all the title elements that have a "lang" attribute with a value of "en" |
| /bookstore/book[price>35.00] | Selects all the book elements of the bookstore element that have a price element with a value greater than 35.00 |
| /bookstore/book[price>35.00]/title | Selects all the title elements of the book elements of the bookstore element that have a price element with a value greater than 35.00 |
XPath handleiding
Jy sal baie meer oor XPath leer in ons XPath-tutoriaal .