54 KiB

Raw Blame History

XPath Tutorial

Part 1: What is XPath?

XPath is a language

"XPath is a language for addressing parts of an XML document"

—XML Path Language 1.0

This abstract from the official specifications says it all:

"XPath is a language": an XPath expression is a character string...
"for addressing parts of an XML document": ...a string that that you pass to an XPath engine acting over an XML (or HTML) document, outputting parts of it, and following the data model explained below.

Why learn XPath?

with XPath, you can navigate everywhere inside a DOM tree
it's a must-have skill for accurate web data extraction
XPath is more powerful than CSS selectors
it allows selection and filtering with a fine-grained look at the text content
XPath allows complex conditioning with axes
XPath is extensible with custom functions (we won’t cover that in this tutorial though)

XPath data model

XPath's data model is a tree of nodes representing a document. Nodes can be either:

element nodes (<p>This is a paragraph</p>),
or attribute nodes (href="page.html" inside an <a> tag),
or text nodes ("I have something to say"),
or comment nodes (),
(or root nodes, or namespace nodes, or processing instructions nodes but we will not cover them here.)

In XPath's data model, everything is a node : elements, attributes, comments... (but not all nodes are elements.)

And nodes have an order, the document order: the order in which they appear in the XML/HTML source.

In effect, this data model allows you to represent everything inside an XML or HTML document, in a structured, ordered and hierarchical way.

Throughout this tutorial, we'll use the following sample HTML page to illustrate how XPath works:

<html>
<head>
  <title>This is a title</title>
  <meta content="text/html; charset=utf-8" http-equiv="content-type">
</head>
<body>
  <div>
    <div>
      <p>This is a paragraph.</p>
      <p>Is this <a href="page2.html">a link</a>?</p>
      <br>
      Apparently.
    </div>
    <div class="second">
      Nothing to add.
      Except maybe this <a href="page3.html">other link</a>.
      <!-- And this comment -->
    </div>
  </div>
</body>
</html>

Here is an ASCII tree representation of our toy HTML document for an XPath engine, according to the data model:

# 0--(ROOT)
 +-- # 1--<html>
     +-- # 2--(TXT): '\n'
     +-- # 3--<head>
     |   +-- # 4--(TXT): '\n  '
     |   +-- # 5--<title>
     |   |   +-- # 6--(TXT): 'This is a title'
     |   +-- # 7--(TXT): '\n  '
     |   +-- # 8--<meta>
     |   |   +-- # 9--(ATTR): content: 'text/html; charset=utf-8'
     |   |   +-- #10--(ATTR): http-equiv: 'content-type'
     |   +-- #11--(TXT): '\n'
     +-- #12--(TXT): '\n'
     +-- #13--<body>
     |   +-- #14--(TXT): '\n  '
     |   +-- #15--<div>
     |   |   +-- #16--(TXT): '\n    '
     |   |   +-- #17--<div>
     |   |   |   +-- #18--(TXT): '\n      '
     |   |   |   +-- #19--<p>
     |   |   |   |   +-- #20--(TXT): 'This is a paragraph.'
     |   |   |   +-- #21--(TXT): '\n      '
     |   |   |   +-- #22--<p>
     |   |   |   |   +-- #23--(TXT): 'Is this '
     |   |   |   |   +-- #24--<a>
     |   |   |   |   |   +-- #25--(ATTR): href: 'page2.html'
     |   |   |   |   |   +-- #26--(TXT): 'a link'
     |   |   |   |   +-- #27--(TXT): '?'
     |   |   |   +-- #28--(TXT): '\n      '
     |   |   |   +-- #29--<br>
     |   |   |   +-- #30--(TXT): '\n      Apparently.\n    '
     |   |   +-- #31--(TXT): '\n    '
     |   |   +-- #32--<div>
     |   |   |   +-- #33--(ATTR): class: 'second'
     |   |   |   +-- #34--(TXT): '\n      Nothing to add.\n      Except maybe this '
     |   |   |   +-- #35--<a>
     |   |   |   |   +-- #36--(ATTR): href: 'page3.html'
     |   |   |   |   +-- #37--(TXT): 'other link'
     |   |   |   +-- #38--(TXT): '. \n      '
     |   |   |   +-- #39--(COMM): ' And this comment '
     |   |   |   +-- #40--(TXT): '\n    '
     |   |   +-- #41--(TXT): '\n  '
     |   +-- #42--(TXT): '\n'
     +-- #43--(TXT): '\n'

You can see various tree branches and leaves:

e.g. <div> or <p>: these are element nodes
(TXT) represent text nodes
(ATTR) represent attribute nodes
(COMM) represent comment nodes

The #<number> are the document orders of each node.

Note

You can also notice that text with only whitespace (space and newlines in our example) are proper nodes, they do have their document order and can be selected with XPath.

In-browser widget and using parsel

To illustrate and learn XPath, we will use an in-browser widget allowing you to play around with XPath expressions and see the output live. We will also illustrate some Python pattern for data extraction with XPath using the parsel library which powers Scrapy selectors under the hood. It is a Python module written on top of lxml.

Note

lxml itself is built using the C library libxml2, which has a conformant XPath 1.0 engine. You should be able to run the same XPath expressions with any XPath 1.0 engine, and get the same results.

This tutorial only showcases XPath 1.0. (XPath has reached version 3, but you can already do a lot with XPath 1.0 and Python. And there's no XPath>1.0 implementation in Python today.)

When showing Python code snippets using Parsel, we assume that we have a Selector -- called doc -- created with the HTML content, similarly to the following:

System Message: WARNING/2 (<stdin>, line 175)

Cannot analyze code. Pygments package not found.

.. code:: python

    import parsel


    htmlsample = '''<html>
    <head>
      <title>This is a title</title>
      <meta content="text/html; charset=utf-8" http-equiv="content-type" />
    </head>
    <body>
      <div>
        <div>
          <p>This is a paragraph.</p>
          <p>Is this <a href="page2.html">a link</a>?</p>
          <br />
          Apparently.
        </div>
        <div class="second">
          Nothing to add.
          Except maybe this <a href="page3.html">other link</a>.
          <!-- And this comment -->
        </div>
      </div>
    </body>
    </html>'''

    doc = parsel.Selector(text=htmlsample)

XPath return types

When applied over a document, an XPath expression can return either:

a node-set -- this is the most common case, and often it's a set of element nodes
a string
a number (floating point)
a boolean

Note

When an XPath expression returns a node-set, you do get a set of nodes, even if there's only one node in the set. With parsel, you get a list of nodes though, not a Python set.

XPath expressions

We will now take a look at some example XPath expressions to get a feeling of how they work. We'll explain the syntax in more details later on.

XPath expressions are passed to an XPath engine as strings.

Selecting the root node of a document (warning: special case)

The root node is a special node: this is a quote from XPath 1.0 specs:

"The root node is the root of the tree. A root node does not occur except as the root of the tree. The element node for the document element is a child of the root node."

Selecting the root node of a document with XPath is one of the shortest XPath expressions: "/" (a string with only a forward slash).

System Message: ERROR/3 (<stdin>, line 242)

Unknown directive type "xpathdemo".

.. xpathdemo:: /

    <html>
    <head>
      <title>This is a title</title>
      <meta content="text/html; charset=utf-8" http-equiv="content-type" />
    </head>
    <body>
      <div>
        <div>
          <p>This is a paragraph.</p>
          <p>Is this <a href="page2.html">a link</a>?</p>
          <br />
          Apparently.
        </div>
        <div class="second">
          Nothing to add.
          Except maybe this <a href="page3.html">other link</a>.
          <!-- And this comment -->
        </div>
      </div>
    </body>
    </html>

This is very similar to cd / in a shell within a Unix filesystem (going to the root directory).

Warning

Unfortunately, this "/" expression does not work as expected with parsel. We get an empty list instead of the root node.

It is a limitation of lxml apparently, because it works with libxml2 directly. In practice though, this doesn't matter much because the root node is virtually never used directly.

Selecting elements

Elements build the structure and hierarchy of the document. An element in HTML (and XML) is what you see in the source code between an opening and corresponding closing tag, and everything in between.

<title>This is a title</title> is a title element,
<p>Is this <a href="page2.html">a link</a>?</p> is a p (paragraph) element.

Selecting elements is probably the most common use-case for XPath on HTML documents.

Elements can have children -- the root node being the ancestor of them all. Their children can also have children and so on. Sometimes, elements only have one child. This hierarchy forms a family tree of nodes.

Note

Text nodes are not elements. (They are still nodes, obviously.) They do not have children nodes, but they are always children of some element.

Therefore, text nodes are always leaves of the document tree.

We said earlier that the document element is a child of the root node. In fact, the document element is the only child of the root node. And for our sample HTML document, it's the top-level <html>...</html> element. Still, selecting it will return a single-node node-set, the XPath expression being /*:

System Message: ERROR/3 (<stdin>, line 309)

Unknown directive type "xpathdemo".

.. xpathdemo:: /*

    <html>
    <head>
      <title>This is a title</title>
      <meta content="text/html; charset=utf-8" http-equiv="content-type" />
    </head>
    <body>
      <div>
        <div>
          <p>This is a paragraph.</p>
          <p>Is this <a href="page2.html">a link</a>?</p>
          <br />
          Apparently.
        </div>
        <div class="second">
          Nothing to add.
          Except maybe this <a href="page3.html">other link</a>.
          <!-- And this comment -->
        </div>
      </div>
    </body>
    </html>

The asterisk here, *, means "any element". And /* means "any element under the root node". HTML documents have only one element like this: the <html> element.

Another example: how to get <title> elements? Use /html/head/title:

System Message: ERROR/3 (<stdin>, line 339)

Unknown directive type "xpathdemo".

.. xpathdemo:: /html/head/title

    <html>
    <head>
      <title>This is a title</title>
      <meta content="text/html; charset=utf-8" http-equiv="content-type" />
    </head>
    <body>
      <div>
        <div>
          <p>This is a paragraph.</p>
          <p>Is this <a href="page2.html">a link</a>?</p>
          <br />
          Apparently.
        </div>
        <div class="second">
          Nothing to add.
          Except maybe this <a href="page3.html">other link</a>.
          <!-- And this comment -->
        </div>
      </div>
    </body>
    </html>

Again, if you are familiar with the Unix filesystem, you probably intuitively understand what this does:

start from the root (of the document)
- select the <html> node (with /html)
  - select the <head> node under the <html> node (appending /head)
    
    select the <title> node under the <head> node (appending /title)

In other words, the XPath expression represents the path from the root node down to the target node(s). Parts of this path are read from left to right, and represent a top-to-bottom direction in the document tree.

Much like a Unix filepath represents the path from the filesystem's root to the target file(s) or directory(ies). There's one major difference with a Unix filesystem though: in an HTML or XML document, an element can have multiple children with the same name. For example, the <div> just under the <body> has 2 <div> children:

System Message: ERROR/3 (<stdin>, line 386)

Unknown directive type "xpathdemo".

.. xpathdemo:: /html/body/div/div

    <html>
    <head>
      <title>This is a title</title>
      <meta content="text/html; charset=utf-8" http-equiv="content-type" />
    </head>
    <body>
      <div>
        <div>
          <p>This is a paragraph.</p>
          <p>Is this <a href="page2.html">a link</a>?</p>
          <br />
          Apparently.
        </div>
        <div class="second">
          Nothing to add.
          Except maybe this <a href="page3.html">other link</a>.
          <!-- And this comment -->
        </div>
      </div>
    </body>
    </html>

Another example is getting the paragraphs inside the first child of that <div> under <body>, there are two of them:

System Message: ERROR/3 (<stdin>, line 413)

Unknown directive type "xpathdemo".

.. xpathdemo:: /html/body/div/div[1]/p

    <html>
    <head>
      <title>This is a title</title>
      <meta content="text/html; charset=utf-8" http-equiv="content-type" />
    </head>
    <body>
      <div>
        <div>
          <p>This is a paragraph.</p>
          <p>Is this <a href="page2.html">a link</a>?</p>
          <br />
          Apparently.
        </div>
        <div class="second">
          Nothing to add.
          Except maybe this <a href="page3.html">other link</a>.
          <!-- And this comment -->
        </div>
      </div>
    </body>
    </html>

Here we're introducing a positional predicate, [1]. The div[1] part means "the first <div> child under its parent".

If you recall, earlier we used a * asterisk to mean any element. There are other elements with those two paragraphs under that very <div>. Let's try and select all of them, regardless of their name:

System Message: ERROR/3 (<stdin>, line 444)

Unknown directive type "xpathdemo".

.. xpathdemo:: /html/body/div/div[1]/*

    <html>
    <head>
      <title>This is a title</title>
      <meta content="text/html; charset=utf-8" http-equiv="content-type" />
    </head>
    <body>
      <div>
        <div>
          <p>This is a paragraph.</p>
          <p>Is this <a href="page2.html">a link</a>?</p>
          <br />
          Apparently.
        </div>
        <div class="second">
          Nothing to add.
          Except maybe this <a href="page3.html">other link</a>.
          <!-- And this comment -->
        </div>
      </div>
    </body>
    </html>

Note

Continuing the filesystem anamogy, * is similar in effect to what you can do in a Unix shell to find files or directories without explicit full names.

See the <br/> being selected? It's an empty element (i.e. with node children) but it is there nonetheless.

Selecting text nodes

If we stay around these <p> and <br> elements, you may have noticed that the ASCII tree representation from the beginning also shows some text after the <br/> break: the string "Apparently.". It is a text node.

Selecting text nodes is a bit different than selecting elements: you use the special text() syntax. Let's try it by replacing the last part of our last XPath expression, forming /html/body/div/div[1]/text():

System Message: ERROR/3 (<stdin>, line 487)

Unknown directive type "xpathdemo".

.. xpathdemo:: /html/body/div/div[1]/text()

    <html>
    <head>
      <title>This is a title</title>
      <meta content="text/html; charset=utf-8" http-equiv="content-type" />
    </head>
    <body>
      <div>
        <div>
          <p>This is a paragraph.</p>
          <p>Is this <a href="page2.html">a link</a>?</p>
          <br />
          Apparently.
        </div>
        <div class="second">
          Nothing to add.
          Except maybe this <a href="page3.html">other link</a>.
          <!-- And this comment -->
        </div>
      </div>
    </body>
    </html>

You may have expected only one text result, the last one, "Apparently.". But we got four! And three of them are blank even. Why is that?

In fact, HTML authors usually indent their tags with whitespace for readability. This does not usually change the layout in your browser. But this whitespace counts as text nodes for XPath's data model, it is not stripped nor filtered.

Let's represent that <div> as a Python string as it appears in the HTML source:

#
#   text node #1                       text node #2                                           text node #3
#     <------>                           <------>                                               <------>
'<div>\n      <p>This is a paragraph.</p>\n      <p>Is this <a href="page2.html">a link</a>?</p>\n      <br>\n  Apparently.\n    </div>'

We've marked the first three text nodes before the non-whitespace only text node.

Another example is to get the text nodes of <title> elements (remember that <title> is an element, and that it happens it contains a text node, with the string content "This is a title"):

System Message: ERROR/3 (<stdin>, line 535)

Unknown directive type "xpathdemo".

.. xpathdemo:: /html/head/title/text()

    <html>
    <head>
      <title>This is a title</title>
      <meta content="text/html; charset=utf-8" http-equiv="content-type" />
    </head>
    <body>
      <div>
        <div>
          <p>This is a paragraph.</p>
          <p>Is this <a href="page2.html">a link</a>?</p>
          <br />
          Apparently.
        </div>
        <div class="second">
          Nothing to add.
          Except maybe this <a href="page3.html">other link</a>.
          <!-- And this comment -->
        </div>
      </div>
    </body>
    </html>

Note

Again, there's only one <title>, and it contains only one text node, but selecting text nodes in <title> returns a single string-value in a list, not one string.

Selecting nodes without a full, explicit path

What we did until now is tell the XPath engine how to get to nodes, node by node, from parent to child, from root node down to target nodes. This assumes that you know the hierarchy of nodes beforehand. This can be the case, but most often than not, either you do not know or you do not want to indicate all the steps from the root node down to the node(s) you are interested in (this can be very error prone -- have you put enough div/div/div...?).

XPath provides a handy shortcut when you do not know at what level you expect your target node to be. Say for example that we want to select all <p> paragraph elements inside the <body>. We don't a-priori know what their parent node is. (For all we know, they can be anywhere under the <body> element.) The shortcut to use is // (two forward slashes). Let's try this: //body//p

System Message: ERROR/3 (<stdin>, line 584)

Unknown directive type "xpathdemo".

.. xpathdemo:: //body//p

    <html>
    <head>
      <title>This is a title</title>
      <meta content="text/html; charset=utf-8" http-equiv="content-type" />
    </head>
    <body>
      <div>
        <div>
          <p>This is a paragraph.</p>
          <p>Is this <a href="page2.html">a link</a>?</p>
          <br />
          Apparently.
        </div>
        <div class="second">
          Nothing to add.
          Except maybe this <a href="page3.html">other link</a>.
          <!-- And this comment -->
        </div>
      </div>
    </body>
    </html>

So we got 2 paragraphs, what we expected.

This also works for text nodes (there are a lot of them in our sample document!). Try //body//text():

System Message: ERROR/3 (<stdin>, line 613)

Unknown directive type "xpathdemo".

.. xpathdemo:: //body//text()

    <html>
    <head>
      <title>This is a title</title>
      <meta content="text/html; charset=utf-8" http-equiv="content-type" />
    </head>
    <body>
      <div>
        <div>
          <p>This is a paragraph.</p>
          <p>Is this <a href="page2.html">a link</a>?</p>
          <br />
          Apparently.
        </div>
        <div class="second">
          Nothing to add.
          Except maybe this <a href="page3.html">other link</a>.
          <!-- And this comment -->
        </div>
      </div>
    </body>
    </html>

Selecting attributes

Elements can also have attributes. In our sample document, we have two <a> elements, each with a href attribute. There's also a <meta> element with two attributes: content and http-equiv.

This is how you can select these attributes, with an @ prefix before the attribute name:

System Message: ERROR/3 (<stdin>, line 649)

Unknown directive type "xpathdemo".

.. xpathdemo:: //a/@href

    <html>
    <head>
      <title>This is a title</title>
      <meta content="text/html; charset=utf-8" http-equiv="content-type" />
    </head>
    <body>
      <div>
        <div>
          <p>This is a paragraph.</p>
          <p>Is this <a href="page2.html">a link</a>?</p>
          <br />
          Apparently.
        </div>
        <div class="second">
          Nothing to add.
          Except maybe this <a href="page3.html">other link</a>.
          <!-- And this comment -->
        </div>
      </div>
    </body>
    </html>

System Message: ERROR/3 (<stdin>, line 674)

Unknown directive type "xpathdemo".

.. xpathdemo:: //meta/@*

    <html>
    <head>
      <title>This is a title</title>
      <meta content="text/html; charset=utf-8" http-equiv="content-type" />
    </head>
    <body>
      <div>
        <div>
          <p>This is a paragraph.</p>
          <p>Is this <a href="page2.html">a link</a>?</p>
          <br />
          Apparently.
        </div>
        <div class="second">
          Nothing to add.
          Except maybe this <a href="page3.html">other link</a>.
          <!-- And this comment -->
        </div>
      </div>
    </body>
    </html>

The * (asterisk) here after @ means the same thing as in /* exept that this is for attributes, and not elements: meaning that you want any attributes, whatever their name.

Get a string representation of an element

The XPath language also comes with a few string functions, that you can wrap around an XPath expression selecting elements:

System Message: ERROR/3 (<stdin>, line 710)

Unknown directive type "xpathdemo".

.. xpathdemo:: string(/html/head/title)

    <html>
    <head>
      <title>This is a title</title>
      <meta content="text/html; charset=utf-8" http-equiv="content-type" />
    </head>
    <body>
      <div>
        <div>
          <p>This is a paragraph.</p>
          <p>Is this <a href="page2.html">a link</a>?</p>
          <br />
          Apparently.
        </div>
        <div class="second">
          Nothing to add.
          Except maybe this <a href="page3.html">other link</a>.
          <!-- And this comment -->
        </div>
      </div>
    </body>
    </html>

This example uses string(<xpathexpression>), one of several handy functions in XPath. string() will concatenate all text content from the selected node and all of its children, recursively, effectively stripping HTML tags.

You may wonder what's the difference between string(/html/head/title) and /html/head/title/text() from earlier? Here, in fact, you get the same result because <title> only has one child text node. (Concatenating this list of one text node is the same as getting it directly with text() at the end.)

But string functions can be very handy when you apply them on nodes that have multiple children and multiple text node children or descendant. What happens when you apply string() on the document <body> for example? You get a text representation of the document, without the tags:

System Message: ERROR/3 (<stdin>, line 752)

Unknown directive type "xpathdemo".

.. xpathdemo:: string(string(//body))

    <html>
    <head>
      <title>This is a title</title>
      <meta content="text/html; charset=utf-8" http-equiv="content-type" />
    </head>
    <body>
      <div>
        <div>
          <p>This is a paragraph.</p>
          <p>Is this <a href="page2.html">a link</a>?</p>
          <br />
          Apparently.
        </div>
        <div class="second">
          Nothing to add.
          Except maybe this <a href="page3.html">other link</a>.
          <!-- And this comment -->
        </div>
      </div>
    </body>
    </html>

Counting elements

We said earlier that XPath expressions could also return numbers. One example of this is counting the number of paragraphs in the document:

System Message: ERROR/3 (<stdin>, line 784)

Unknown directive type "xpathdemo".

.. xpathdemo:: count(//p)

    <html>
    <head>
      <title>This is a title</title>
      <meta content="text/html; charset=utf-8" http-equiv="content-type" />
    </head>
    <body>
      <div>
        <div>
          <p>This is a paragraph.</p>
          <p>Is this <a href="page2.html">a link</a>?</p>
          <br />
          Apparently.
        </div>
        <div class="second">
          Nothing to add.
          Except maybe this <a href="page3.html">other link</a>.
          <!-- And this comment -->
        </div>
      </div>
    </body>
    </html>

Note

With parsel, you get a floating point number back, and in the form of a string. This is specific to parsel. Another XPath engine might return a native floating point number.

Another example: get the number of attributes in the document (whatever their parent element):

System Message: ERROR/3 (<stdin>, line 817)

Unknown directive type "xpathdemo".

.. xpathdemo:: count(//@*)

    <html>
    <head>
      <title>This is a title</title>
      <meta content="text/html; charset=utf-8" http-equiv="content-type" />
    </head>
    <body>
      <div>
        <div>
          <p>This is a paragraph.</p>
          <p>Is this <a href="page2.html">a link</a>?</p>
          <br />
          Apparently.
        </div>
        <div class="second">
          Nothing to add.
          Except maybe this <a href="page3.html">other link</a>.
          <!-- And this comment -->
        </div>
      </div>
    </body>
    </html>

Boolean operations

XPath expressions can also return booleans. This is not that usueful by itself, but it becomes handy when used in predicates (that we will cover a bit later).

For example, testing the number of paragraphs:

System Message: ERROR/3 (<stdin>, line 853)

Unknown directive type "xpathdemo".

.. xpathdemo:: count(//p) = 2

    <html>
    <head>
      <title>This is a title</title>
      <meta content="text/html; charset=utf-8" http-equiv="content-type" />
    </head>
    <body>
      <div>
        <div>
          <p>This is a paragraph.</p>
          <p>Is this <a href="page2.html">a link</a>?</p>
          <br />
          Apparently.
        </div>
        <div class="second">
          Nothing to add.
          Except maybe this <a href="page3.html">other link</a>.
          <!-- And this comment -->
        </div>
      </div>
    </body>
    </html>

System Message: ERROR/3 (<stdin>, line 877)

Unknown directive type "xpathdemo".

.. xpathdemo:: count(//p) = 42

    <html>
    <head>
      <title>This is a title</title>
      <meta content="text/html; charset=utf-8" http-equiv="content-type" />
    </head>
    <body>
      <div>
        <div>
          <p>This is a paragraph.</p>
          <p>Is this <a href="page2.html">a link</a>?</p>
          <br />
          Apparently.
        </div>
        <div class="second">
          Nothing to add.
          Except maybe this <a href="page3.html">other link</a>.
          <!-- And this comment -->
        </div>
      </div>
    </body>
    </html>

Part 2: Location Paths: how to move inside the document tree

A Location path is the most common XPath expression.

It is used to move in any direction from a starting point (the context node) to any node(s) in the tree:

It is a string, with a series of “location steps”: "step1 / step2 / step3 ..."
It represents the selection and filtering of nodes, processed step by step, from left to right.
Each step is of the form: AXIS :: NODETEST [PREDICATE]*

So the examples we saw earlier are or contain an XPath expression: /html/head/title, //body//p etc.

Note: whitespace does NOT matter, except for “//” and “..” (“/ /” and “. .” are syntax errors.). The following 3 expressions produce the same result

System Message: WARNING/2 (<stdin>, line 923)

Cannot analyze code. Pygments package not found.

.. code:: python

    doc.xpath('/html/head/title')

[(1) '<title>This is a title</title>']

System Message: WARNING/2 (<stdin>, line 936)

Cannot analyze code. Pygments package not found.

.. code:: python

    doc.xpath('/    html   / head   /title')

[(1) '<title>This is a title</title>']

System Message: WARNING/2 (<stdin>, line 949)

Cannot analyze code. Pygments package not found.

.. code:: python

    doc.xpath('''
        /html
            /head
                /title''')

[(1) '<title>This is a title</title>']

So don’t be afraid of indenting your XPath expressions to improve readability.

Relative vs. absolute paths

Location paths can be relative or absolute:

"step1/step2/step3" is relative
"/step1/step2/step3" is absolute

i.e. an absolute path is a relative path starting with "/" (slash)

In other terms, absolute paths are relative to the root node.

Tip: use relative paths whenever possible. This prevents unexpected selection of same nodes in loop iterations.

For example, in our sample document, only one <div> contains paragraphs. Looping on each <div> and using the absolute location path //p will produce the same result for each iteration: returning ALL paragraphs in the document everytime.

System Message: WARNING/2 (<stdin>, line 988)

Cannot analyze code. Pygments package not found.

.. code:: python

    for div in doc.xpath('//body//div'):
        print(div.xpath('//p'))

[(1) '<p>This is a paragraph.</p>'
 (2) '<p>Is this <a href="page2.html">a link</a>?</p>']
[(1) '<p>This is a paragraph.</p>'
 (2) '<p>Is this <a href="page2.html">a link</a>?</p>']
[(1) '<p>This is a paragraph.</p>'
 (2) '<p>Is this <a href="page2.html">a link</a>?</p>']

Compare this with using the relative 'p' or './p' expression that will only look at children <p> under each <div>, and only one of those <div> will show having paragraphs as shown below:

System Message: WARNING/2 (<stdin>, line 1008)

Cannot analyze code. Pygments package not found.

.. code:: python

    for div in doc.xpath('//body//div'):
        print(div.xpath('p'))

[]
[(1) '<p>This is a paragraph.</p>'
 (2) '<p>Is this <a href="page2.html">a link</a>?</p>']
[]

System Message: WARNING/2 (<stdin>, line 1022)

Cannot analyze code. Pygments package not found.

.. code:: python

    for div in doc.xpath('//body//div'):
        print(div.xpath('./p'))

[]
[(1) '<p>This is a paragraph.</p>'
 (2) '<p>Is this <a href="page2.html">a link</a>?</p>']
[]

Abbreviated syntax

What we’ve seen earlier is in fact the “abbreviated syntax” for XPath expressions.

The full syntax is quite verbose (but you sometimes need it):

Abbreviated syntax	Full syntax
`/html/head/title`	``/child::html /child:: head /child:: title` ` System Message: WARNING/2 (`<stdin>`, line 1048); backlink Inline literal start-string without end-string.
`//meta/@content`	`/descendant-or-self::node() /child::meta / attribute::content`
`//div/div[@class="second" ]`	`/descendant-or-self::node() /child::div /c hild::div [attribute::class = "second"]`
`//div/a/text()`	`/descendant-or-self::node() /child::div /c hild::a /child::text()`

What are these child::, descendant-or-self:: and attribute::, you may ask? They're axes.

Axes: moving around

Remember: each step of an XPath location path is of the form AXIS :: NODETEST [PREDICATE]*.

The "axis" is the first part of each location path step. It can be explicit, or implicit in abbreviated syntax. For example, in /html/head/title, the child:: axis is omitted in each step.

In this section, we'll use explicit axes as much as we can.

AXIS :: _nodetest [predicate]*_

Axes give the direction to go next, one location step at a time

self (where you are)
parent, child (direct hop)
ancestor, ancestor-or-self, descendant, descendant-or-self (multi-hop)
following, following-sibling, preceding, preceding-sibling (document order)
attribute, namespace (non-element)

Move up or down the tree: self, child, descendant, parent, ancestor

Let's assume that we have selected the first <div> element in our sample document, the one just under the <body> element:

System Message: WARNING/2 (<stdin>, line 1093)

Cannot analyze code. Pygments package not found.

.. code:: python

    first_div = doc.xpath('//body/div')[0]
    first_div

<div>
    <div>
      <p>This is a paragraph.</p>
      <p>Is this <a href="page2.html">a link</a>?</p>
      <br>
      Apparently.
    </div>
    <div class="second">
      Nothing to add.
      Except maybe this <a href="page3.html">other link</a>.
      <!-- And this comment -->
    </div>
  </div>

The self axis represents the context node, i.e. where you are currently in the Location Path step. (This may not sounds very useful, but we will see later when this can be handy.)

System Message: WARNING/2 (<stdin>, line 1123)

Cannot analyze code. Pygments package not found.

.. code:: python

    first_div.xpath('self::*')

[(1) '<div>
    <div>
      <p>This is a paragraph.</p>
      <p>Is this <a href="page2.html">a link</a>?</p>
      <br>
      Apparently.
    </div>
    <div class="second">
      Nothing to add.
      Except maybe this <a href="page3.html">other link</a>.
      <!-- And this comment -->
    </div>
  </div>']

If you chain self:: steps, you'll stay on the same context node:

System Message: WARNING/2 (<stdin>, line 1150)

Cannot analyze code. Pygments package not found.

.. code:: python

    first_div.xpath('self::*/self::*/self::*')

[(1) '<div>
    <div>
      <p>This is a paragraph.</p>
      <p>Is this <a href="page2.html">a link</a>?</p>
      <br>
      Apparently.
    </div>
    <div class="second">
      Nothing to add.
      Except maybe this <a href="page3.html">other link</a>.
      <!-- And this comment -->
    </div>
  </div>']

self:: is usually seen in abbreviated form: i.e. a '.' (dot). So you could aslo use:

System Message: WARNING/2 (<stdin>, line 1178)

Cannot analyze code. Pygments package not found.

.. code:: python

    first_div.xpath('.')

[(1) '<div>
    <div>
      <p>This is a paragraph.</p>
      <p>Is this <a href="page2.html">a link</a>?</p>
      <br>
      Apparently.
    </div>
    <div class="second">
      Nothing to add.
      Except maybe this <a href="page3.html">other link</a>.
      <!-- And this comment -->
    </div>
  </div>']

System Message: WARNING/2 (<stdin>, line 1203)

Cannot analyze code. Pygments package not found.

.. code:: python

    first_div.xpath('././.')

[(1) '<div>
    <div>
      <p>This is a paragraph.</p>
      <p>Is this <a href="page2.html">a link</a>?</p>
      <br>
      Apparently.
    </div>
    <div class="second">
      Nothing to add.
      Except maybe this <a href="page3.html">other link</a>.
      <!-- And this comment -->
    </div>
  </div>']

The child axis is for immediate children nodes of the context node. Here, our context <div> node has 2 <div> children:

System Message: WARNING/2 (<stdin>, line 1231)

Cannot analyze code. Pygments package not found.

.. code:: python

    first_div.xpath('child::*')

[(1) '<div>
      <p>This is a paragraph.</p>
      <p>Is this <a href="page2.html">a link</a>?</p>
      <br>
      Apparently.
    </div>'
 (2) '<div class="second">
      Nothing to add.
      Except maybe this <a href="page3.html">other link</a>.
      <!-- And this comment -->
    </div>']

child is in fact the default axis, hence it can be omitted (e.g. we saw that /html/head/title is equivalent of /child::html/child::head/child::title.)

The parent axis is the dual of child: you go up one level in the DOM:

System Message: WARNING/2 (<stdin>, line 1261)

Cannot analyze code. Pygments package not found.

.. code:: python

    first_div.xpath('parent::*')

[(1) '<body>
  <div>
    <div>
      <p>This is a paragraph.</p>
      <p>Is this <a href="page2.html">a link</a>?</p>
      <br>
      Apparently.
    </div>
    <div class="second">
      Nothing to add.
      Except maybe this <a href="page3.html">other link</a>.
      <!-- And this comment -->
    </div>
  </div>
</body>']

There's an alias for parent::: it's .. (2 dots, much like in a Unix filesystem):

System Message: WARNING/2 (<stdin>, line 1291)

Cannot analyze code. Pygments package not found.

.. code:: python

    first_div.xpath('..')

[(1) '<body>
  <div>
    <div>
      <p>This is a paragraph.</p>
      <p>Is this <a href="page2.html">a link</a>?</p>
      <br>
      Apparently.
    </div>
    <div class="second">
      Nothing to add.
      Except maybe this <a href="page3.html">other link</a>.
      <!-- And this comment -->
    </div>
  </div>
</body>']

Let's simplify our ASCII tree representation from earlier to only consider element nodes:

# 0--(ROOT)
 +-- # 1--<html>
     +-- # 3--<head>
     |   +-- # 5--<title>
     |   +-- # 8--<meta>
     +-- #13--<body>
         +-- #15--<div>
             +-- #17--<div>
             |   +-- #19--<p>
             |   +-- #22--<p>
             |   |   +-- #24--<a>
             |   +-- #29--<br>
             +-- #32--<div>
                 +-- #35--<a>

With this simplified tree representation, this is what self, child and parent select:

                # 0--(ROOT)
                 +-- # 1--<html>
                     +-- # 3--<head>
                     |   +-- # 5--<title>
                     |   +-- # 8--<meta>
parent::* ---------> +-- #13--<body>
                         |
self::* ------------->   +-- #15--<div>
                             |
child::*----+----------->    +-- #17--<div>
            |                |   +-- #19--<p>
            |                |   +-- #22--<p>
            |                |   |   +-- #24--<a>
            |                |   +-- #29--<br>
            +----------->    +-- #32--<div>
                                 +-- #35--<a>

Recursively go up or down

The descendant axis is similar to child but also goes deeper in the tree, looking at children of each child, recursively:

System Message: WARNING/2 (<stdin>, line 1366)

Cannot analyze code. Pygments package not found.

.. code:: python

    first_div.xpath('descendant::*')

[(1) '<div>
      <p>This is a paragraph.</p>
      <p>Is this <a href="page2.html">a link</a>?</p>
      <br>
      Apparently.
    </div>'
 (2) '<p>This is a paragraph.</p>'
 (3) '<p>Is this <a href="page2.html">a link</a>?</p>'
 (4) '<a href="page2.html">a link</a>'
 (5) '<br>'
 (6) '<div class="second">
      Nothing to add.
      Except maybe this <a href="page3.html">other link</a>.
      <!-- And this comment -->
    </div>'
 (7) '<a href="page3.html">other link</a>']

You might guess already what ancestor is for: it is the dual axis of descendant:

System Message: WARNING/2 (<stdin>, line 1397)

Cannot analyze code. Pygments package not found.

.. code:: python

    first_div.xpath('ancestor::*')

[(1) '<html>
<head>
  <title>This is a title</title>
  <meta content="text/html; charset=utf-8" http-equiv="content-type">
</head>
<body>
  <div>
    <div>
      <p>This is a paragraph.</p>
      <p>Is this <a href="page2.html">a link</a>?</p>
      <br>
      Apparently.
    </div>
    <div class="second">
      Nothing to add.
      Except maybe this <a href="page3.html">other link</a>.
      <!-- And this comment -->
    </div>
  </div>
</body>
</html>'
 (2) '<body>
  <div>
    <div>
      <p>This is a paragraph.</p>
      <p>Is this <a href="page2.html">a link</a>?</p>
      <br>
      Apparently.
    </div>
    <div class="second">
      Nothing to add.
      Except maybe this <a href="page3.html">other link</a>.
      <!-- And this comment -->
    </div>
  </div>
</body>']

Special case of `descendant-or-self` axis

TODO: explain

System Message: WARNING/2 (<stdin>, line 1450)

Cannot analyze code. Pygments package not found.

.. code:: python

    first_div.xpath('./descendant-or-self::node()/text()')

[(1) '
    '
 (2) '
      '
 (3) 'This is a paragraph.'
 (4) '
      '
 (5) 'Is this '
 (6) 'a link'
 (7) '?'
 (8) '
      '
 (9) '
      Apparently.
    '
 (10) '
    '
 (11) '
      Nothing to add.
      Except maybe this '
 (12) 'other link'
 (13) '.
      '
 (14) '
    '
 (15) '
  ']

Move "sideways": children nodes of the same parent

If nodes can have parents, children, ancestors and descendants, they can also have siblings (to continue the family metaphor). Siblings are nodes that have the same parent node.

Some siblings may come before the context node (they appear before in the document, their order is lower), or they can come after the context node. There are 2 axis for these 2 directions: preceding-sibling and following-sibling.

Let's first select this paragraph from our sample document: <p>Is this <a href="page2.html">a link</a>?</p>. It's the 2nd child of the 1st <div> of the <div> we used above:

System Message: WARNING/2 (<stdin>, line 1505)

Cannot analyze code. Pygments package not found.

.. code:: python

    paragraph = first_div.xpath('child::div[1]/child::p[2]')[0]

You can notice above that we started using 2 new patterns along with the axes:

child::div vs. child::*: * means "any element node" (this is a NODETEST that we'll cover afterwards)
[1] and [2]: which mean first and second in the current step's node-set (this is a kind of PREDICATE that we'll cover afterwards also)

System Message: WARNING/2 (<stdin>, line 1518)

Cannot analyze code. Pygments package not found.

.. code:: python

    paragraph.xpath('preceding-sibling::*')

[(1) '<p>This is a paragraph.</p>']

System Message: WARNING/2 (<stdin>, line 1531)

Cannot analyze code. Pygments package not found.

.. code:: python

    paragraph.xpath('following-sibling::*')

[(1) '<br>']

Again, let's see which elements were selected in our ASCII tree representation:

                # 0--(ROOT)
                 +-- # 1--<html>
                     +-- # 3--<head>
                     |   +-- # 5--<title>
                     |   +-- # 8--<meta>
                     +-- #13--<body>
                         |
                         +-- #15--<div>
                             |
                             +-- #17--<div>
                             |   |
                             |   |
preceding-sibling::* ----------> +-- #19--<p>
                             |   |
                             |   |
self::* -----------------------> +-- #22--<p>
                             |   |   |
                             |   |   +-- #24--<a>
                             |   |
                             |   |
following-sibling::* ----------> +-- #29--<br>
                             |
                             |
                             +-- #32--<div>
                                 +-- #35--<a>

System Message: WARNING/2 (<stdin>, line 1575)

Cannot analyze code. Pygments package not found.

.. code:: python

    paragraph.xpath('following-sibling::node()')

[(1) '
      '
 (2) '<br>'
 (3) '
      Apparently.
    ']

Nodes before and after, in document order

preceding and following are 2 special axes that do not look at the tree hierarchy, but work on the document order of nodes.

Remember, all nodes in XPath data model have an order, called the document order. Node 1 is the first node in the HTML source, node 2 is the node appearing next etc.

  #1    #2    #3   ...
<html><head><title>...

System Message: WARNING/2 (<stdin>, line 1608)

Cannot analyze code. Pygments package not found.

.. code:: python

    paragraph.xpath('preceding::*')

[(1) '<head>
  <title>This is a title</title>
  <meta content="text/html; charset=utf-8" http-equiv="content-type">
</head>'
 (2) '<title>This is a title</title>'
 (3) '<meta content="text/html; charset=utf-8" http-equiv="content-type">'
 (4) '<p>This is a paragraph.</p>']

System Message: WARNING/2 (<stdin>, line 1627)

Cannot analyze code. Pygments package not found.

.. code:: python

    paragraph.xpath('following::*')

[(1) '<br>'
 (2) '<div class="second">
      Nothing to add.
      Except maybe this <a href="page3.html">other link</a>.
      <!-- And this comment -->
    </div>'
 (3) '<a href="page3.html">other link</a>']

Note that preceding does not include ancestors and following does not include descendants.

This property is mentioned in XPath specs like this:

The ancestor, descendant, following, preceding and self axes partition a document (ignoring attribute and namespace nodes): they do not overlap and together they contain all the nodes in the document.

i.e. document == self U (ancestor U preceding) U (descendant U following)

Node tests

A "node test" is the second part of each step in a location path.

axis :: NODETEST _[predicate]*_

Node tests select node types along the step's axis.

They can be:

a name test:
such as "p", "title" or "a" for elements: /html/head/title contains 3 steps, each with a name test node test
or "href" or "src" for attributes: /a/@href selects "href" attributes of
a *node type test":
"node()": any node type
"text()": text nodes
"comment()": comment nodes
"*" (an asterisk): the meaning depends on the axis:
- an "*" step alone selects any element nodes (a.k.a tags)
- an "@*" selects any attribute node

Note: text() is not a function call that converts a node to it's text representation, it's just a test on the node type.

Compare these 2 expressions:

System Message: WARNING/2 (<stdin>, line 1692)

Cannot analyze code. Pygments package not found.

.. code:: python

    paragraph.xpath('child::text()')

[(1) 'Is this '
 (2) '?']

System Message: WARNING/2 (<stdin>, line 1706)

Cannot analyze code. Pygments package not found.

.. code:: python

    paragraph.xpath('string(self::*)')

[(1) 'Is this a link?']

child::text() selector all children nodes that are also text nodes. "a" is part of the <a> inside the paragraph, sot it's not selected.

Whereas string(self::*) applies to the paragraph (the context node, selected with self::*) and recursively gets text content of children, children of children and so on.

Predicates

axis :: nodetest ** [PREDICATE]* **

Predicates are the last part of each step in a location path. Predicates are optional.

They are used to further filter nodes on properties that cannot be expressed with the step's axis and node test.

Remember that XPath location paths work step by step. Each step produces a node-set for each node from the previous step's node-set, with possibly more than 1 node in each node set.

You may not be interested in all nodes from a node test.

The syntax for predicates is simple: just surround conditions withing square brackets. What's inside the square brackets can be:

a number (see positional predicates below)
a location path: the predicate will select nodes for which the location path matches at least a node
a boolean operation: for example to test a condition on text content or count of children

Positional predicates

The first use-case is selecting nodes based on their position in a node-set. Node-sets order depends on the axis, but let's consider that the order of a node in a node-set is the document order.

Let's say we don't want the 2 paragraphs in the <div> we looked at earlier, only the first one:

System Message: WARNING/2 (<stdin>, line 1762)

Cannot analyze code. Pygments package not found.

.. code:: python

    doc.xpath('//body/div/div/p')

[(1) '<p>This is a paragraph.</p>'
 (2) '<p>Is this <a href="page2.html">a link</a>?</p>']

System Message: WARNING/2 (<stdin>, line 1776)

Cannot analyze code. Pygments package not found.

.. code:: python

    doc.xpath('//body/div/div/p[1]')

[(1) '<p>This is a paragraph.</p>']

If you want the last node in a node-set, you can use last():

System Message: WARNING/2 (<stdin>, line 1791)

Cannot analyze code. Pygments package not found.

.. code:: python

    doc.xpath('//body/div/div[last()]')

[(1) '<div class="second">
      Nothing to add.
      Except maybe this <a href="page3.html">other link</a>.
      <!-- And this comment -->
    </div>']

Position ranges

TODO: things like //table/tbody/tr[position() > 2]

Location paths as predicates

TODO: things like //table[tr/div/a]

Boolean predicates

TODO: things like //table[count(tr)=10]

Special case of string value tests

TODO: things like //table[.//img/@src="pic.png"] or //table[th="Some headers"]

Special trick for testing multiple node names

TODO: things like ./descendant-or-self::*[self::ul or self::ol]

Nested predicates

We said that location paths can be used as predicate. And location paths can have predicates. So it's possible end up with nested predicates.

System Message: WARNING/2 (<stdin>, line 1840)

Cannot analyze code. Pygments package not found.

.. code:: python

    #                <------predicate --------->
    #                    <-nested predicate->
    doc.xpath('//div[p  [a/@href="page2.html"]  ]')

[(1) '<div>
      <p>This is a paragraph.</p>
      <p>Is this <a href="page2.html">a link</a>?</p>
      <br>
      Apparently.
    </div>']

In fact, the above is equivalent to //div[p/a/@href="page2.html"] with no nesting:

System Message: WARNING/2 (<stdin>, line 1863)

Cannot analyze code. Pygments package not found.

.. code:: python

    doc.xpath('//div[p/a/@href="page2.html"]')

[(1) '<div>
      <p>This is a paragraph.</p>
      <p>Is this <a href="page2.html">a link</a>?</p>
      <br>
      Apparently.
    </div>']

Order of predicates is important

You can have multiple predicates in sequence per step, each within its [] brackets, i.e. steps in the form of axis::nodetest[predicate#1][predicate#2][predicate#3]...

Predicates are processed in order, from left to right. And the output of one predicate is fed into the next predicate filter, much like steps produce node-sets for the next step to process.

So the order of predicates is important.

The following 2 location paths produce different results:

System Message: WARNING/2 (<stdin>, line 1896)

Cannot analyze code. Pygments package not found.

.. code:: python

    doc.xpath('//div[2][@class="second"]')

[(1) '<div class="second">
      Nothing to add.
      Except maybe this <a href="page3.html">other link</a>.
      <!-- And this comment -->
    </div>']

System Message: WARNING/2 (<stdin>, line 1913)

Cannot analyze code. Pygments package not found.

.. code:: python

    doc.xpath('//div[@class="second"][2]')

[]

The 2nd produces nothing. Why is that?

//div[2][@class="second"] looks at div elements that are the 2nd child of their parent (because div means child::div, and [2] will select the 2nd node in the current node-set. In our document this happens only once. The final predicate, [@class="second"], filter nodes that have a "class" attribute with value "second". This happens to be valid for that 2nd child div.

On the contrary, //div[@class="second"][2] will first produce //div[@class="second"], which only produces single-node node-sets (again, there's only 1 div with "class" attribute with value "second"). So the subsequent [2] predicate will never match with single-node node-sets.

Abbreviation cheatsheet

Abbreviated step	Meaning
`*` (asterisk)	all element nodes (i.e. not text nodes, not attribute nodes;
	remember that `.//*` is not the same as `.//node()`;
	also, there's not `element()` node test
`@*`	`attribute::*` (all attribute nodes)
`//`	``/descendant-or-self::node()/ \| System Message: WARNING/2 (`<stdin>`, line 1958); backlink Inline literal start-string without end-string. exactly this, nothing mo re, nothing less, \| so``//`is not the same as`/descen System Message: WARNING/2 (`<stdin>`, line 1961); backlink* Inline emphasis start-string without end-string. dant-or-self::`\|`.``(a single dot) System Message: WARNING/2 (`<stdin>`, line 1962); backlink* Inline emphasis start-string without end-string. System Message: WARNING/2 (`<stdin>`, line 1962); backlink Inline literal start-string without end-string. \|``self::node()``, the context n System Message: WARNING/2 (`<stdin>`, line 1963); backlink Inline substitution_reference start-string without end-string. System Message: WARNING/2 (`<stdin>`, line 1963); backlink Inline literal start-string without end-string. System Message: WARNING/2 (`<stdin>`, line 1963); backlink Inline literal start-string without end-string. ode; useful for formation a relative XPath \| e.g.``.//tr System Message: WARNING/2 (`<stdin>`, line 1966) Block quote ends without a blank line; unexpected unindent. `\|`..`(2 dots) \|`par System Message: WARNING/2 (`<stdin>`, line 1967) Definition list ends without a blank line; unexpected unindent. ent::node()`

TODO: explain why //* is not the same as /descendant-or-self::*

String functions

TODO

Part 3: Use-cases for web scraping

TODO

Text extraction

TODO

Attributes extraction

TODO

Attribute names extractions

TODO

CSS Selectors

TODO

Loop on elements (table rows, lists)

TODO

Element boundaries & XPath buckets (advanced)

TODO

EXSLT extensions

TODO

Summary of tips

Use relative XPath expressions whenever possible
Know your axes!
Don't forget that XPath has string() and normalize-space() functions
``text()`` is a node test, not a function call
CSS selectors are very handy, easier to maintain, but also less powerful than XPath

</html>

54 KiB Raw Blame History Unescape Escape

XPath Tutorial

Part 1: What is XPath?

XPath is a language

Why learn XPath?

XPath data model

In-browser widget and using parsel

XPath return types

XPath expressions

Selecting the root node of a document (warning: special case)

Selecting elements

Selecting text nodes

Selecting nodes without a full, explicit path

Selecting attributes

Get a string representation of an element

Counting elements

Boolean operations

Part 2: Location Paths: how to move inside the document tree

Relative vs. absolute paths

Abbreviated syntax

Axes: moving around

Move up or down the tree: self, child, descendant, parent, ancestor

Recursively go up or down

Special case of descendant-or-self axis

Move "sideways": children nodes of the same parent

Nodes before and after, in document order

Node tests

Predicates

Positional predicates

Position ranges

Location paths as predicates

Boolean predicates

Special case of string value tests

Special trick for testing multiple node names

Nested predicates

Order of predicates is important

Abbreviation cheatsheet

String functions

Part 3: Use-cases for web scraping

Text extraction

Attributes extraction

Attribute names extractions

CSS Selectors

Loop on elements (table rows, lists)

Element boundaries & XPath buckets (advanced)

EXSLT extensions

Summary of tips

54 KiB

Raw Blame History

Special case of `descendant-or-self` axis