June 2010 Edition
Computer Science Department, University of Cape Town
| MSc-IT Study Material June 2010 Edition Computer Science Department, University of Cape Town |
The XML Path Language (XPath) supplies a mechanism to address particular nodes or sets of nodes in an XML document. XPath expressions can be used to write precise expressions to select nodes without using procedural DOM statements. For example, we can address particular nodes using expressions like:
uct/title uct/version/number uct/author/@office
Expressions are separated by "/".
In general, each subexpression matches one or more nodes in the DOM tree.
Each sub-expression has the form: axis::node[condition1][condition2]... where axis can be used to select children, parents, descendants, siblings, and so on.
Symbols may be used for the possible axes:
| Expression | What it selects in current context |
|---|---|
| title | "title" children |
| * | All children |
| @office | "office" attribute |
| author[1] | First author node |
| /uct/title[last()] | Last title within uct node at top level of document |
| //author | All author nodes that are descendant from top level |
| . | Context node |
| .. | Parent node |
| version[number] | Version nodes that have "number" children |
| version[number='1.0'] | Version nodes for which "number" has content of "1.0" |