R4R provide basic XPATH Tutorials concept with
XPATH Examples .
Through R4R you can develop XPATH programming concept. R4R provide
XPATH Interview Questions with answers.R4R provide XPATH Languages study materials in easy way.
XPATH Interview Questions with Answers
1.1 XPATH Subjective Questions with Answers
1.2 XPATH Interview Questions with Answers
1.3 XPATH Objective Questions And Answers
1.3 FAQS
Introduction of XPath:
XPath is the solution to finding information in an XML document. XPath uses
expressions to find elements, attributes, and other information in your XML.
XML documents have a tree structure
-XPath allows you to concisely describe sets of XML elements and attributes in
this tree.
-Analogy to file system paths.
- A file system hierarchy is a tree of directories and files.
- A filesystem path describes how to reach a specific file, starting either from
the root, or the current working directory.
-XPath exploits this intuitive notion of a path, and extends it to XML
documents.
Nodes of XPath:
In the XML tree available for XPath expressions, there are 7 node
types:
- The root node (one per document)
- Element nodes
- Attribute nodes
- Text nodes
- Comment nodes
- Processing instruction nodes
- Namespace nodes
Simple Example :
<?xml version="1.0" encoding="ISO-8859-1"?>
<bookstore>
<book>
<title lang="eng">Harry Potter</title>
<price>29.99</price>
</book>
<book>
<title lang="eng">Learning XML</title>
<price>39.95</price>
</book>
</bookstore>
|
Some Expression How to Locate path:
| Expression |
Description |
| / |
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 |
| Path Expression |
Result |
| /bookstore |
Selects the root element bookstore |
| 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 |
| |
|
| |
|
Advantage of XPath:
1.Flexible expression: The user may use whatever tags/attributes seem intuitive when designing the
schema
2.latent semantics: Many users prefer to figure out the semantics when/if necessary
3.Application Specific Constraint Checking
4.Core Technology: XSLT/XPath is a "core
technology" which is well supported, well understood, and with lots of material
written on it.
5.Expressive Power: XSLT/XPath is a very powerful
language. Most, if not every, constraint that you might ever need to express can
be expressed using 6.XSLT/XPath. Thus you don't
have to learn multiple schema languages to express your additional constraints
7.Long Term Support: XSLT/XPath is well supported,
and will be around for a long time.
Disadvantage of XParh:
1.Separate Documents: With this approach you
will write your XML Schema document, then you will write a separate XSLT/XPath
document to express additional constraints. Keeping the two documents in synch
needs to be carefully managed
2.Efficiency is access limited
.
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