In this XPATH tutorial we will see example of selecting elements based
upon its value or attribute value. We will see how to select between two
elements based upon value of its child elements or based upon value of its
attribute. XPATH is an important concept to understand if you are working with
XML files. Most of Back-office platform relies on XML
files for transporting data from one system to other and if you are working
on any back-office or middle office system in Java or .NET, its important to know
about XPATH and be able to use XPATH to select data from XML. Some time back I
have shared my XPATH
notes for Java programmer and this example shows true power of XPATH as how convenient its to made selective decision.
For those who are completely new in XML and XPATH, XPATH is great xml tool which allows you to query XML document and select or retrieve selective data much like SQL but if you are new to XPATH or haven't had much experience with XML tool and technology than you will struggle to find correct syntax of XPATH for your different need.
For those who are completely new in XML and XPATH, XPATH is great xml tool which allows you to query XML document and select or retrieve selective data much like SQL but if you are new to XPATH or haven't had much experience with XML tool and technology than you will struggle to find correct syntax of XPATH for your different need.
XPATH to select an element based on attribute and value
Here is our sample xml, which we will use in this XPATH tutorial :
<orders>
<order orderNumber="1">
<item>Electronics</item>
<total>100</total>
</order>
<order orderNumber="2">
<item>Computers</item>
<total>200</total>
</order>
<order orderNumber="3">
<item>food</item>
<total>300</total>
</order>
</orders>
<order orderNumber="1">
<item>Electronics</item>
<total>100</total>
</order>
<order orderNumber="2">
<item>Computers</item>
<total>200</total>
</order>
<order orderNumber="3">
<item>food</item>
<total>300</total>
</order>
</orders>
In the first example of XPATH expression, we will see how to select a total element for the order which has the item value "Electronics"
XPATH :
/orders/order[item/text()='Electronics']/total
value : 100
here text() function returns value of <item> element
[] brackets are used to define conditions or
predicate, which is comparing text of <item> tag with “Electronics”.
Similarly, we can extend this XPATH to find the total for Orders where the item is
Computers and food
/orders/order[item/text()='Computers']/total
200
/orders/order[item/text()='food']/total
300
On the second example of XPATH expression, we will find the total element for an order whose orderNumber attribute has value "2"
XPATH : /orders/order[@orderNumber='1']/total
value : 100
here [] is used for condition and @ is used to
get value from attribute.
/orders/order[@orderNumber='2']/total
200
/orders/order[@orderNumber='3']/total
300
If you are new to XML or XPATH I suggest using XML-SPY tool it has in
built XPATH evaluator which shows the result of XPATH as soon as you type and
it supports XPath1.0 and XPATH2.0 as beta. It also has XPATH copy functionality
so you can just select any element in XML in its grid view and copy its XPATH
to use in your Java program.
Other Java and XML tutorials you may like
XPath is indeed worth learning for any XML Java developers. By using XPath you can retrieve any element from XML documents, just like SQL.
ReplyDeleteyou nailed it man!
ReplyDelete@Zeshan, thank you very mcuh. Glad that you find this XPath tutorial in Java useful.
ReplyDelete