XPATH
‫מבוא‬
MCSD Doron Amir
www.doronamir.com
What is XPath?
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A W3C Standard
Not written in XML
Defines parts of an XML document
Defines a standard functions
Major element in XSLT
w3c ‫לפי כללי ה‬
XML ‫ אינה‬XPATH ‫ה‬
XML ‫ מגדירה חלקים ממסמך ה‬XPATH ‫ה‬
XML ‫ מגדירה פונקציות שימושיות לטיפול במסמך‬XPATH ‫ה‬
XSLT ‫ הינה חלק עקרי מ‬XPATH ‫ה‬
XPath Expression
‫ מכילה ביטויים עבר זיהוי צמתים במסמך‬XPATH 
CATALOG ‫ שבתוך אלמנט השורש‬CD ‫ שבתוך האלמנטים‬Price ‫בחירת כל האלמנטים‬
“/catalog/cd/price”
Root Element
The CD Element
The Price Element
<?xml version="1.0" encoding="ISO-8859-1"?>
<catalog>
<cd country="USA">
<title>Empire Burlesque</title>
<artist>Bob Dylan</artist>
<price>10.90</price> </cd>
<catalog>
XPath Expression
/catalog/cd/price = Absolute path
 //cd = All the CD elemen ts in the document:
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Selecting Unknown Elements
/catalog/cd/*
Select All the child elements of all the cd
XPath Expression
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/catalog/cd/*
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All the child elements of all the cd elements
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/catalog/*/price
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All the price elements that are grandchild elements of the catalog
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/*/*/price
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All price elements which have 2 ancestors
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//*
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All elements in the document
Parent
/catalog/*/price
child element
/*/*/price
grandchild elements
/catalog/cd/*
Selecting Branches
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/catalog/cd[1]
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first cd child element
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/catalog/cd[last()]
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last cd child element
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/catalog/cd[price]
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element that have a price element
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/catalog/cd[price=10.90]
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all the cd elements that have a price element with a value of 10.90:
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/catalog/cd[price=10.90]/price
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all the Price elements that have a price element with a value of 10.90
Several Paths
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/catalog/cd/title | /catalog/cd/artist
all the title and artist elements of the cd element of the catalog element
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//title | //artist
all the title and artist elements in the
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document:
//title | //artist | //price
all the title, artist and price elements in the
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document:
/catalog/cd/title | //artist
all the title elements of the
cd element and
all the artist elements in the
document
Attributes
Specified by the @ prefix
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//@country
all attributes named country
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//cd[@country]
all cd elements which have an attribute named country:
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//cd[@*]
all cd elements which have any attribute:
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//cd[@country='UK']
all cd elements which have an attribute named country with a value of 'UK':
Location
child::text()
child::node()
attribute::X
attribute::*
Selects the text node children
Selects all the children of the current node
Selects the X attribute of the current node
Selects all attributes of the current node
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child::price[price=9.90]
Selects all price elements that are children of the current node
with a price element that equals 9.90
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child::cd[position()=1]
Selects the first cd child of the current node
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child::cd[position()=last()]
Selects the last cd child of the current node
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child::cd[position()<6]
Selects the first five cd children of the current node
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/descendant::cd[position()=7]
Selects the seventh cd element in the document
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child::cd[attribute::type="classic"]
Selects all cd children of the current node that have a type attribute with value classic
short
child::cd[attribute::type="classic"]
cd[@type="classic"]
parent::node()/child::cd
../cd
XPath Expression
Example
Result
cd
Selects all the cd elements that are children of the current node
*
Selects all child elements of the current node
text()
Selects all text node children of the current node
@src
Selects the src attribute of the current node
@*
Selects all the attributes of the current node
cd[1]
Selects the first cd child of the current node
cd[last()]
Selects the last cd child of the current node
XPath Expression
*/cd
Selects all cd grandchildren of the current node
/book/chapter[3]/para[1]
Selects the first para of the third chapter of the book
//cd
Selects all the cd descendants of the document root and thus
selects all cd elements in the same document as the current
node
.
Selects the current node
.//cd
Selects the cd element descendants of the current node
..
Selects the parent of the current node
../@src
Selects the src attribute of the parent of the current node
cd[@type="classic"]
Selects all cd children of the current node that have a type
attribute with value classic
XPath Expression
cd[@type="classic"]
Selects all cd children of the current node that have
a type attribute with value classic
cd[@type="classic"][5]
Selects the fifth cd child of the current node that has
a type attribute with value classic
cd[5][@type="classic"]
Selects the fifth cd child of the current node
if that child has a type attribute with value classic
cd[@type and @country]
Selects all the cd children of the current node
that have both a type attribute and a country attribute
XPath Functions
string-length('Beatles')
Result: 7
 substring('Beatles',1,4)
Result: 'Beat'
 round(3.14)
Result: 3
 number(false())
Result: 0
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XPath Functions
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ceiling(3.14)
Result: 4
floor(3.14)
Result: 3
string(314)
Result: '314'
translate('12:30','0123','abcd')
Result: 'bc:da'
translate('12:30','03','54')
Result: '12:45'
<html>
<body>
<script type="text/vbscript">
Example
set xmlDoc=CreateObject("Microsoft.XMLDOM")
xmlDoc.async="false"
xmlDoc.load("cdcatalog.xml")
path="//cd[price<9.90]"
set nodes=xmlDoc.selectNodes(path)
for each x in nodes
document.write("<xmp>")
document.write(x.xml)
document.write("</xmp>")
next
</script>
</body>
</html>
<cd>
<title>Sylvias Mother</title>
<artist>Dr.Hook</artist>
<country>UK</country>
<company>CBS</company>
<price>8.10</price>
<year>1973</year>
</cd>
<cd>
<title>Maggie May</title>
<artist>Rod Stewart</artist>
<country>UK</countr
<company>Pickwick</comp
any>
<price>8.50</price>
<year>1990</year>
</cd>
XPATH
‫מבוא‬
MCSD Doron Amir
www.doronamir.com