Complex XPath axes Methods

Complex XPath axes Methods

1. Parent

2. Child

3. Ancestor

4. Descendant

5. Following

6. Following-Sibling

7. Preceding

8. Preceding-Sibling

We'll use a sample XML structure related to vehicles to explore various XPath axes. 

Sample XML File 

<garage> <vehicle> <make>Toyota</make> <model>Camry</model> <year>2022</year> </vehicle> <vehicle> <make>Honda</make> <model>Civic</model> <year>2023</year> </vehicle> <vehicle> <make>Ford</make> <model>Mustang</model> <year>2021</year> </vehicle> </garage>

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1. Parent Axis

The parent axis selects the parent of the current node.

Example 1: Basic

XPath: parent::vehicle

Explanation: If the current node is <model>, the XPath parent::vehicle selects the <vehicle> element that contains this <model>.

Example 2: Intermediate

XPath: parent::*

Explanation: If the current node is <year>, the XPath parent::* selects the parent <vehicle> element. This selects any parent node, not just <vehicle>.

Example 3: Advanced

XPath: parent::garage

Explanation: If the current node is <make> inside any <vehicle>, the XPath parent::garage selects the <garage> element. This is useful when navigating up to the root element.

2. Child Axis

The child axis selects all children of the current node.

Example 1: Basic

XPath: child::vehicle

Explanation: From <garage>, the XPath child::vehicle selects all <vehicle> elements.

Example 2: Intermediate

XPath: child::make

Explanation: From <vehicle>, the XPath child::make selects the <make> element.

Example 3: Advanced

XPath: child::*

Explanation: From <vehicle>, the XPath child::* selects all child elements of <vehicle>, including <make>, <model>, and <year>.

3. Ancestor Axis

The ancestor axis selects all ancestors (parent, grandparent, etc.) of the current node.

Example 1: Basic

XPath: ancestor::*

Explanation: If the current node is <year>, the XPath ancestor::* selects the <vehicle> and <garage> elements.

Example 2: Intermediate

XPath: ancestor::vehicle

Explanation: If the current node is <model> inside <vehicle>, the XPath ancestor::vehicle selects the current <vehicle> element.

Example 3: Advanced

XPath: ancestor::garage

Explanation: If the current node is <model> inside a <vehicle>, the XPath ancestor::garage selects the <garage> element.

4. Descendant Axis

The descendant axis selects all descendants (children, grandchildren, etc.) of the current node.

Example 1: Basic

XPath: descendant::*

Explanation: From <garage>, the XPath descendant::* selects all elements: <vehicle>, <make>, <model>, and <year>.

Example 2: Intermediate

XPath: descendant::make

Explanation: From <garage>, the XPath descendant::make selects all <make> elements within <vehicle>.

Example 3: Advanced

XPath: descendant::year

Explanation: From <vehicle>, the XPath descendant::year selects the <year> element within that <vehicle>.

5. Following Axis

The following axis selects everything in the document after the closing tag of the current node.

Example 1: Basic

XPath: following::*

Explanation: If the current node is the first <vehicle>, the XPath following::* selects the second <vehicle> and the third <vehicle>.

Example 2: Intermediate

XPath: following::*

Explanation: If the current node is <make> of the first <vehicle>, the XPath following::* selects the <model> and <year> of the first <vehicle>, and all <vehicle> elements after it.

Example 3: Advanced

XPath: following::*

Explanation: If the current node is <year> of the first <vehicle>, the XPath following::* selects the <make>, <model>, and <year> of the remaining <vehicle> elements.

6. Following-Sibling Axis

The following-sibling axis selects all siblings after the current node.

Example 1: Basic

XPath: following-sibling::*

Explanation: If the current node is the first <vehicle>, the XPath following-sibling::* selects the second <vehicle> and the third <vehicle>.

Example 2: Intermediate

XPath: following-sibling::*

Explanation: If the current node is <make> of the first <vehicle>, the XPath following-sibling::* selects the <model> and <year> of the first <vehicle> and the next <vehicle> elements.

Example 3: Advanced

XPath: following-sibling::*

Explanation: If the current node is <year> of the first <vehicle>, the XPath following-sibling::* selects the <make>, <model>, and <year> of the second and third <vehicle> elements.

7. Preceding Axis

The preceding axis selects all nodes that appear before the current node in the document.

Example 1: Basic

XPath: preceding::*

Explanation: If the current node is the second <vehicle>, the XPath preceding::* selects the first <vehicle> and its <make>, <model>, and <year>.

Example 2: Intermediate

XPath: preceding::*

Explanation: If the current node is <make> of the second <vehicle>, the XPath preceding::* selects all nodes before it, including the first <vehicle> and its child elements.

Example 3: Advanced

XPath: preceding::*

Explanation: If the current node is <year> of the second <vehicle>, the XPath preceding::* selects all nodes before it, including the first <vehicle> and its children.

8. Preceding-Sibling Axis

The preceding-sibling axis selects all siblings before the current node.

Example 1: Basic

XPath: preceding-sibling::*

Explanation: If the current node is the second <vehicle>, the XPath preceding-sibling::* selects the first <vehicle>.

Example 2: Intermediate

XPath: preceding-sibling::*

Explanation: If the current node is <year> of the second <vehicle>, the XPath preceding-sibling::* selects the <model> of the second <vehicle> and all siblings before it.

Example 3: Advanced

XPath: preceding-sibling::*

Explanation: If the current node is <make> of the second <vehicle>, the XPath preceding-sibling::* selects the <make> of the first <vehicle>.

Combining All Categories: 10 XPath Queries

1. XPath: parent::vehicle/child::model

   • Explanation: From <make>, select the sibling <model> within the same <vehicle>.

2. XPath: descendant::vehicle/ancestor::garage

   • Explanation: From any <vehicle>, select the <garage> element.

3. XPath: following-sibling::vehicle/descendant::year

   • Explanation: From the first <vehicle>, select the <year> of all following <vehicle> elements.

4. XPath: preceding-sibling::vehicle/child::make

   • Explanation: From the second <vehicle>, select the <make> of the preceding sibling <vehicle>.

5. XPath: following::*[preceding-sibling::vehicle]/descendant::make

   • Explanation: From the first <vehicle>, select the <make> elements of all following <vehicle> elements.

6. XPath: ancestor::garage/descendant::vehicle/child::model

   • Explanation: From <make> inside <vehicle>, select all <model> elements of <vehicle> descendants within <garage>.

7. XPath: preceding::vehicle/following-sibling::vehicle/descendant::model

   • Explanation: From the third <vehicle>, select the <model> elements of preceding <vehicle> siblings and all following <vehicle> siblings.

8. XPath: descendant::make[following-sibling::vehicle]/ancestor::garage

   • Explanation: From <make> elements that have following <vehicle> siblings, select the <garage> ancestor.

9. XPath: following::vehicle[preceding-sibling::vehicle]/descendant::year

   • Explanation: From <make> of any <vehicle>, select the <year> of all following <vehicle> elements with preceding siblings.

10. XPath: preceding::vehicle/child::*[following-sibling::vehicle]

    • Explanation: From the second <vehicle>, select all children that are siblings of any following <vehicle> elements.