Sintaks XPath
XPath menggunakan ekspresi jalur untuk memilih node atau kumpulan node dalam dokumen XML. Node dipilih dengan mengikuti jalur atau langkah-langkah.
Dokumen Contoh XML
Kami akan menggunakan dokumen XML berikut dalam contoh di bawah ini.
<?xml version="1.0" encoding="UTF-8"?>
<bookstore>
<book>
<title lang="en">Harry Potter</title>
<price>29.99</price>
</book>
<book>
<title lang="en">Learning XML</title>
<price>39.95</price>
</book>
</bookstore>
Memilih Node
XPath menggunakan ekspresi jalur untuk memilih node dalam dokumen XML. Node dipilih dengan mengikuti jalur atau langkah-langkah. Ekspresi jalur yang paling berguna tercantum di bawah ini:
| Expression | Description |
|---|---|
| nodename | Selects all nodes with the name "nodename" |
| / | Selects from the root node |
| // | Selects nodes in the document from the current node that match the selection no matter where they are |
| . | Selects the current node |
| .. | Selects the parent of the current node |
| @ | Selects attributes |
Pada tabel di bawah ini kami telah mencantumkan beberapa ekspresi jalur dan hasil dari ekspresi:
| Path Expression | Result |
|---|---|
| bookstore | Selects all nodes with the name "bookstore" |
| /bookstore | Selects the root element bookstore Note: If the path starts with a slash ( / ) it always represents an absolute path to an element! |
| bookstore/book | Selects all book elements that are children of bookstore |
| //book | Selects all book elements no matter where they are in the document |
| bookstore//book | Selects all book elements that are descendant of the bookstore element, no matter where they are under the bookstore element |
| //@lang | Selects all attributes that are named lang |
Predikat
Predikat digunakan untuk menemukan simpul tertentu atau simpul yang mengandung nilai tertentu.
Predikat selalu disematkan dalam tanda kurung siku.
Pada tabel di bawah ini kami telah mencantumkan beberapa ekspresi jalur dengan predikat dan hasil dari ekspresi:
| Path Expression | Result |
|---|---|
| /bookstore/book[1] | Selects the first book element that is the child of the bookstore element.
Note: In IE 5,6,7,8,9 first node is[0], but according to W3C, it is [1]. To solve this problem in IE, set the SelectionLanguage to XPath: In JavaScript: xml.setProperty("SelectionLanguage","XPath"); |
| /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 |
Memilih Node Tidak Dikenal
Wildcard XPath dapat digunakan untuk memilih node XML yang tidak dikenal.
| Wildcard | Description |
|---|---|
| * | Matches any element node |
| @* | Matches any attribute node |
| node() | Matches any node of any kind |
Pada tabel di bawah ini kami telah mencantumkan beberapa ekspresi jalur dan hasil dari ekspresi:
| Path Expression | Result |
|---|---|
| /bookstore/* | Selects all the child element nodes of the bookstore element |
| //* | Selects all elements in the document |
| //title[@*] | Selects all title elements which have at least one attribute of any kind |
Memilih Beberapa Jalur
Dengan menggunakan | operator dalam ekspresi XPath Anda dapat memilih beberapa jalur.
Pada tabel di bawah ini kami telah mencantumkan beberapa ekspresi jalur dan hasil dari ekspresi:
| Path Expression | Result |
|---|---|
| //book/title | //book/price | Selects all the title AND price elements of all book elements |
| //title | //price | Selects all the title AND price elements in the document |
| /bookstore/book/title | //price | Selects all the title elements of the book element of the bookstore element AND all the price elements in the document |