xpath-helper 0.1.3

Build complicated XPath queries without the hassle - JavaScript & Python

A chainable API to build complex XPath queries along the different XPath axes. Available both in Python and JavaScript.

• Documentation — Consult the quick start guide and the online documentation.

Installation

xpath-helper requires python 3.5+ and can be installed using pip:

pip install xpath-helper

Quick-start

You can chain method call on the different XPath axes and easily add filters.

from xpath_helper import xh, filter

# Finds a paragraph <p> containing a CSS class 'very-nice-p'
p = xh.get_element_by_tag('p', filter.attribute_contains('class', 'very-nice-p'))
str(p) # "//p[contains(@class, 'very-nice-p')]"

# Finds the paragraph that is following the above one
next_p = p.get_following_sibling_by_tag('p')
str(next_p) # "//p[contains(@class, 'very-nice-p')]/following-sibling::p"

# Finds the modal containing a button with text "Register" 
modal = xh.get_element(filter.value_equals('Register')).get_ancestor(filter.attribute_equals('class', 'modal'))
str(modal) # "//*[text() = 'Register']/ancestor::*[@class='modal']"

# An elaborated filter with a boolean expression
li = xh.get_element_by_tag("li", filter.and_operator(
  filter.or_operator(
    filter.value_contains("JavaScript"), filter.value_contains("Python")
  ),
  filter.has_attribute("data-description")
))
str(li) # "//li[((text()[contains(., 'JavaScript')] or text()[contains(., 'Python')]) and @data-description)]"

Chaining

XPath natively lets your build complex queries chaining them along its different axes. Read this article to understand the different XPath axes.

This library let you do exactly the same by chaining method calls along the different axes: descendant aliased as element, descendant-or-self, child, parent, ancestor, ancestor-or-self, preceding, preceding-sibling, following, following-sibling.

For each axis, xpath-helper provides 3 methods, like for instance get_element(filter), get_element_by_tag(tag, filter), get_element_by_svg_tag(svgTag, filter) for the descendant axis aliased as element.

The complete Python API can be found here.

from xpath_helper import xh, filter

# Finds an element into the page, moves to its parent, 
# finds a brother node of the parent positioned after it.
el = xh.get_element_by_tag(
    'p', filter.attribute_contains('class', 'very-nice-p')
).get_parent().get_following_sibling_by_tag('p')
str(el) # "//p[contains(@class, 'very-nice-p')]/../following-sibling::p"

# Finds an element into the page, moves to its ancestor 
# containing 'very-nice-p' ass CSS class, 
# finds a brother node of the ancestor positioned before it.
el = xh.get_element_by_tag(
    'p', filter.attribute_contains('class', 'very-nice-p')
).get_ancestor_by_tag(
  'div'
).get_preceding_sibling(filter.has_attribute('data-foo-bar'))
str(el) # "//p[contains(@class, 'very-nice-p')]/../following-sibling::p//p[contains(@class, 'very-nice-p')]/ancestor::div/preceding-sibling::*[@data-foo-bar]"

It is also possible to keep a relative path in a variable and re-use it after.

from xpath_helper import xh, filter
# Stores the path of a modal window
modal = xh.get_element(filter.attribute_contains('class', 'modal'))
# Finds the Submit button inside the modal window
submit_button = modal.get_element_by_tag('button', filter.value_equals('Submit'))
# Finds the Cancel button inside the modal window
cancel_button = modal.get_element_by_tag('button', filter.value_equals('Cancel'))

Filters

To select elements more precisely you can add filters: on attributes, on element values, element position, and combining them with conditional operators: and_operator(...), or_operator(...), and not_operator(...).

The complete filter API can be found here.

Attributes

Find below a few examples of filters on attributes.

from xpath_helper import xh, filter
# Looks for an element that has a class attribute equals to 'foo'
el = xh.get_element(filter.attribute_equals('class', 'foo'))
# Looks for an element that has a class attribute containing 'bar'
el = xh.get_element(filter.attribute_contains('class', 'bar'))
# Looks for an element that has the attribute 'alt'
img = xh.get_element_by_tag('img', filter.has_attribute('alt'))
# Looks for all the li element with a data-attribute superior to 3
li = xh.get_element_by_tag('li', filter.attribute_greater_than('data-index', 3))

Values

Find below a few examples of filters on node values.

from xpath_helper import xh, filter

# Looks for a button whose text is 'Submit'
button = xh.get_element_by_tag('button', filter.value_equals('Submit'))
# Looks for an element whose text contains 'foobar'
el = xh.get_element(filter.value_contains('foobar'))
# Looks for all the li element with a value superior to 3
li = xh.get_element_by_tag('li', filter.value_greater_than(3))

Position

Find below a few examples of filters on node position.

from xpath_helper import xh, filter

# Looks for the first li element in ul list
first = xh.get_element_by_tag('ul').get_element_by_tag('li', filter.get_first())
# Looks for the first li element in ul list
last = xh.get_element_by_tag('ul').get_element_by_tag('li', filter.get_last())
# Looks for the third li element in ul list
third = xh.get_element_by_tag('ul').get_element_by_tag('li', filter.get(3))

Conditional expression

Find below a few examples of filters with conditional expression.

from xpath_helper import xh, filter

# Finds an element that has a CSS class 'a-link' and contains an attribute href
el = xh.get_element(
  filter.attribute_contains('class', 'a-link').and_operator(
    filter.has_attribute('href')
  )
)
str(el) # "//*[contains(@class, 'a-link') and (@href)]"

# Finds an element that has a CSS class 'foo' or a CSS class 'bar'
el = xh.get_element(
  filter.attribute_contains('class', 'foo').or_operator(
    filter.attribute_contains('class', 'bar')
  )
)
str(el) # "//*[contains(@class, 'foo') or (contains(@class, 'bar'))]"

# Builds a complex logical expression combining and & or
el = xh.get_element(
  filter.and_operator(
    filter.or_operator(
      filter.value_contains("JavaScript"),
      filter.value_contains("Pyhton")
    ),
      filter.value_contains("package")
  )
)
str(el) # "//*[((text()[contains(., 'JavaScript')] or text()[contains(., 'Pyhton')]) and text()[contains(., 'package')])]"

SVG

Navigating into SVG elements from an HTML file can be tricky with XPath, that is why a subset of functions have been added. They are all ending with ...by_svg_tag and can be used as below.

from xpath_helper import xh, filter

# Stores the path of a modal window
path = xh.get_element_by_svg_tag('path', filter.attribute_equals('d', 'M 310 130 L 90 130 L 90 183.63'))
str(path) # "//*[local-name() = 'path'][@d='M 310 130 L 90 130 L 90 183.63']"

# Finds the Submit button inside the modal window
g = xh.get_element_by_svg_tag(
  'path', filter.attribute_equals('id', 'id-path')
).get_ancestor_by_svg_tag('g')
str(g) # "//*[local-name() = 'path'][@id='id-path']/ancestor::*[local-name() = 'g']"