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XPath Location Paths
A location path expression results in a node-set.
Location Path Expression
A location path can be absolute or relative.
An absolute location path starts with a slash ( / ) and a relative location
path does not. In both cases the location path consists of one or more location
steps, each separated by a slash:
An absolute location path:
/step/step/...
A relative location path:
step/step/...
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The location steps are evaluated in order one at a time, from left to right.
Each step is evaluated against the nodes in the current node-set. If the
location path is absolute, the current node-set consists of the root node. If
the location path is relative, the current node-set consists of the node where
the expression is being used. Location steps consist of:
- an axis (specifies the tree relationship between the nodes selected by the
location step and the current node)
- a node test (specifies the node type and expanded-name of the nodes
selected by the location step)
- zero or more predicates (use expressions to further refine the set of
nodes selected by the location step)
The syntax for a location step is:
axisname::nodetest[predicate]
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Example:
Axes and Node Tests
An axis defines a node-set relative to the current node. A node test is used to identify a node within an axis. We can perform a node
test by name or by type.
| AxisName |
Description |
| ancestor |
Contains all ancestors (parent, grandparent, etc.) of the current node Note:
This axis will always include the root node, unless the current node is the
root node |
| ancestor-or-self |
Contains the current node plus all its ancestors (parent, grandparent, etc.) |
| attribute |
Contains all attributes of the current node |
| child |
Contains all children of the current node |
| descendant |
Contains all descendants (children, grandchildren, etc.) of the current node Note:
This axis never contains attribute or namespace nodes |
| descendant-or-self |
Contains the current node plus all its descendants (children, grandchildren,
etc.) |
| following |
Contains everything in the document after the closing tag of the current node |
| following-sibling |
Contains all siblings after the current node Note: If the current
node is an attribute node or namespace node, this axis will be empty |
| namespace |
Contains all namespace nodes of the current node |
| parent |
Contains the parent of the current node |
| preceding |
Contains everything in the document that is before the starting tag of the
current node |
| preceding-sibling |
Contains all siblings before the current node Note: If the current
node is an attribute node or namespace node, this axis will be empty |
| self |
Contains the current node |
Examples
| Example |
Result |
| child::cd |
Selects all cd elements that are children of the current node (if
the current node has no cd children, it will select an empty node-set) |
| attribute::src |
Selects the src attribute of the current node (if the current
node has no src attribute, it will select an empty node-set) |
| child::* |
Selects all child elements of the current node |
| attribute::* |
Selects all attributes of the current node |
| child::text() |
Selects the text node children of the current node |
| child::node() |
Selects all the children of the current node |
| descendant::cd |
Selects all the cd element descendants of the current node |
| ancestor::cd |
Selects all cd ancestors of the current node |
| ancestor-or-self::cd |
Selects all cd ancestors of the current node and, if the
current node is a cd element, the current node as well |
| child::*/child::price |
Selects all price grandchildren of the current node
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| / |
Selects the document root |
Predicates
A predicate filters a node-set into a new node-set. A predicate is placed inside square brackets
( [ ] ).
Examples
| Example |
Result |
| child::price[price=9.90] |
Selects all price elements that are children of the current node with a price
element that equals 9.90 |
| child::cd[position()=1] |
Selects the first cd child of the current node |
| child::cd[position()=last()] |
Selects the last cd child of the current node |
| child::cd[position()=last()-1] |
Selects the last but one cd child of the current node |
| child::cd[position()<6] |
Selects the first five cd children of the current node |
| /descendant::cd[position()=7] |
Selects the seventh cd element in the document |
| child::cd[attribute::type="classic"] |
Selects all cd children of the current node that have a type attribute with
value classic |
Location Path Abbreviated Syntax
Abbreviations can be used when describing a location path.
The most important abbreviation is that child:: can be omitted from a
location step.
| Abbr |
Meaning |
Example |
| none |
child:: |
cd is short for child::cd |
| @ |
attribute:: |
cd[@type="classic"] is short for
child::cd[attribute::type="classic"] |
| . |
self::node() |
.//cd is short for
self::node()/descendant-or-self::node()/child::cd |
| .. |
parent::node() |
../cd is short for
parent::node()/child::cd
|
| // |
/descendant-or-self::node()/ |
//cd is short for
/descendant-or-self::node()/child::cd |
Examples
| 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 |
| */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 |
| 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 an country attribute |
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