Say I have the following HTML:
<div class="instruction" id="scan-prompt">
<span class="long instruction">Scan </span>
<span id="slot-to-scan">A-2</span>
<span class="long instruction"> to prep</span>
</div>
And I'm trying to write an XPATH selector like this
//div[#id='scan-prompt' and normalize-space()='Scan A-2 to prep']
Is there a way to see what the normalize-space output actually is?
I know you can do $x("//div[#id='scan-prompt']) in chrome debugger but I don't know how to go from that to seeing the output of normalize-space.
Why can you not simply use the path expression
normalize-space(//div[#id='scan-prompt'])
to see what the normalized string value would look like? Other than that, what normalize-space() does exactly is:
Removing any leading or trailing whitespaces from the string argument
Collapsing any sequence of whitespace characters to just one whitespace character
If handed an element node as an argument (as is the case with your original expression), the function evaluates the string value of that element node. The string value of an element node is the concatenation of all its descendant text nodes.
The result of normalize-space(//div[#id='scan-prompt']) is, given the input you show (whitespace marked with "+"):
Scan+A-2+to+prep
Without invoking normalize-space(), for example string(//div[#id='scan-prompt']):
+
Scan+
A-2+
to+prep+
+
So, simply use path expressions that do nothing else than either giving back a string value or a normalized string value. With Google Chrome by using an XPath expression inside $x().
Related
Let's say I have a piece of HTML like this:
<a>Ask Question<other/>more text</a>
I can match this piece of XPath:
//a[text() = 'Ask Question']
Or...
//a[text() = 'more text']
Or I can use dot to match the whole thing:
//a[. = 'Ask Questionmore text']
This post describes this difference between . (dot) and text(), but in short the first returns a single element, where the latter returns a list of elements. But this is where it gets a bit weird to me. Because while text() can be used to match either of the elements on the list, this is not the case when it comes to the XPath function contains(). If I do this:
//a[contains(text(), 'Ask Question')]
...I get the following error:
Error: Required cardinality of first argument of contains() is one or zero
How can it be that text() works when using a full match (equals), but doesn't work on partial matches (contains)?
For this markup,
<a>Ask Question<other/>more text</a>
notice that the a element has a text node child ("Ask Question"), an empty element child (other), and a second text node child ("more text").
Here's how to reason through what's happening when evaluating //a[contains(text(),'Ask Question')] against that markup:
contains(x,y) expects x to be a string, but text() matches two text nodes.
In XPath 1.0, the rule for converting multiple nodes to a string is this:
A node-set is converted to a string by returning the string-value of
the node in the node-set that is first in document order. If the
node-set is empty, an empty string is returned. [Emphasis added]
In XPath 2.0+, it is an error to provide a sequence of text nodes to a function expecting a string, so contains(text(),'substr') will cause an error for more than one matching text node.
In your case...
XPath 1.0 would treat contains(text(),'Ask Question') as
contains('Ask Question','Ask Question')
which is true. On the other hand, be sure to notice that contains(text(),'more text') will evaluate to false in XPath 1.0. Without knowing the (1)-(3) above, this can be counter-intuitive.
XPath 2.0 would treat it as an error.
Better alternatives
If the goal is to find all a elements whose string value contains the substring, "Ask Question":
//a[contains(.,'Ask Question')]
This is the most common requirement.
If the goal is to find all a elements with an immediate text node child equal to "Ask Question":
//a[text()='Ask Question']
This can be useful when wishing to exclude strings from descendent elements in a such as if you want this a,
<a>Ask Question<other/>more text</a>
but not this a:
<a>more text before <not>Ask Question</not> more text after</a>
See also
How contains() handles a nodeset first arg
How to use XPath contains() for specific text?
Testing text() nodes vs string values in XPath
The reason for this is that the contains function doesn't accept a nodeset as input - it only accepts a string. (Well, it may be engine dependent, because it works for Python's lxml module. According to the specification, it should convert the value of the first node in the set to a string and act on that. See also XPath contains(text(),'some string') doesn't work when used with node with more than one Text subnode)
//a[text() = 'Ask Question'] is matching any a elements which contain a text node which equals Ask Question.
//a[text() = 'more text'] is matching any a elements which contain a text node which equals more text.
So both of these expressions match the same a element.
You can re-work your query to //a[text()[contains(., 'Ask Question')]] so that the contains method will only act on a single text node at a time.
Using regular expressions (in Notepad++), I want to find all JSON sections that contain the string foo. Note that the JSON just happens to be embedded within a limited set of HTML source code which is loaded into Notepad++.
I've written the following regex to accomplish this task:
({[^}]*foo[^}]*})
This works as expected in all the input that is possible.
I want to improve my workflow, so instead of just finding all such JSON sections, I want to write a regex to remove all the HTML & JSON that does not match this expression. The result will be only JSON sections that contain foo.
I tried using the Notepad++ regex Replace functionality with this find expression:
(?:({[^}]*?foo[^}]*?})|.)+
and this replace expression:
$1\n\n$2\n\n$3\n\n$4\n\n$5\n\n$6\n\n$7\n\n$8\n\n$9\n\n
This successfully works for the last occurrence of foo within the JSON, but does not find the rest of the occurrences.
How can I improve my code to find all the occurrences?
Here is a simplified minimal example of input and desired output. I hope I haven't simplified it too much for it to be useful:
Simplified input:
<!DOCTYPE html>
<html>
<div dat="{example foo1}"> </div>
<div dat="{example bar}"> </div>
<div dat="{example foo2}"> </div>
</html>
Desired output:
{example foo1}
{example foo2}
You can use
{[^}]*foo[^}]*}|((?s:.))
Replace with (?1:$0\n). Details:
{[^}]*foo[^}]*} - {, zero or more chars other than }, foo, zero or more chars other than } and then a }
| - or
((?s:.)) - Capturing group 1: any one char ((?s:...) is an inline modifier group where . matches all chars including line break chars, same as if you enabled . matches newline option).
The (?1:$0\n) replacement pattern replaces with an empty string if Group 1 was matched, else the replacement is the match text + a newline.
See the demo and search and replace dialog settings:
Updates
The comment section was full tried to suggest a code here,
Let me know if this is a bit close to your intended result,
Find: ({.+?[\n]*foo[ \d]*})|.*?
Replace all: $1
Also added Toto's example
<a href="javascript:void(0)" title="home">
<span class="menu_icon">Maybe more text here</span>
Home
</a>
So for above code when I write //a as XPath, it gets highlighted, but when I write //a[contains(text(), 'Home')], it is not getting highlighted. I think this is simple and should have worked.
Where's my mistake?
Other answers have missed the actual problem here:
Yes, you could match on #title instead, but that's not why OP's
XPath is failing where it may have worked previously.
Yes, XML and XPath are case sensitive, so Home is not the same as
home, but there is a Home text node as a child of a, so OP is
right to use Home if he doesn't trust #title to be present.
Real Problem
OP's XPath,
//a[contains(text(), 'Home')]
says to select all a elements whose first text node contains the substring Home. Yet, the first text node contains nothing but whitespace.
Explanation: text() selects all child text nodes of the context node, a. When contains() is given multiple nodes as its first argument, it takes the string value of the first node, but Home appears in the second text node, not the first.
Instead, OP should use this XPath,
//a[text()[contains(., 'Home')]]
which says to select all a elements with any text child whose string value contains the substring Home.
If there weren't surrounding whitespace, this XPath could be used to test for equality rather than substring containment:
//a[text()[.='Home']]
Or, with surrounding whitespace, this XPath could be used to trim it away:
//a[text()[normalize-space()= 'Home']]
See also:
Testing text() nodes vs string values in XPath
Why is XPath unclean constructed? Why is text() not needed in predicate?
XPath: difference between dot and text()
yes you are doing 2 mistakes, you're writing Home with an uppercase H when you want to match home with a lowercase h. also you're trying to check the text content, when you want to check check the "title" attribute. correct those 2, and you get:
//a[contains(#title, 'home')]
however, if you want to match the exact string home, instead of any a that has home anywhere in the title attribute, use #zsbappa's code.
You can try this XPath..Its just select element by attribute
//a[#title,'home']
I want to select with XPath only the value from span class="value" without the currency sign character.
<span class="infoValue">
<span class="value">
<span class="currencyLeft">$</span>
1000
</span>
</span>
//span[#class='infoValue']//span[#class='value']
With this xpath, I can select "$1000" . How can I remove or get only the "1000" without " $ " sign with XPath?
When I try with this.
//span[#class='infoValue']//span[#class='value']/span[not(currencyLeft)]"
I only get again the currency sign "$".
'normalize-space(//span[#class="value"]/text()[normalize-space()])'
This XPath,
normalize-space(//span[#class='currencyLeft']/following-sibling::text())
will select
1000
as requested.
You can, of course, specify the heritage to /span[#class='currencyLeft'] more specifically.
There are <span> nodes and text nodes. If you select a span node, you always get the $, because every span node contains it and XPath only selects complete nodes with all their descendants. But $ and 1000 are text nodes, so you can choose one of them:
//span[#class='infoValue']/span[#class='value']/text()
Alternatively, you can treat the span as string and remove the string "$" ("$" is a $, not the $ in the XML file, since latter $ is associated with a certain position/parent/... in the XML file). Although this only works for a single value:
normalize-space(translate(//span[#class='infoValue']/span[#class='value'], "$", ""))
substring-after(//span[#class="value"], "$")
use substring-after function:
Returns the substring of the first argument string that follows the
first occurrence of the second argument string in the first argument
string, or the empty string if the first argument string does not
contain the second argument string.
This is the HTML code:
<div> <span></span> Elangovan </div>
I want to write an XPath for the div based on its contained text. I tried
//div[contains(text(),'Elangovan')]
but this is not working.
Replace text() with string():
//div[contains(string(), "Elangovan")]
Or, you can check that span's following text sibling contains the text:
//div[contains(span/following-sibling::text(), "Elangovan")]
Also see:
Difference between text() and string()
Alternatively to alecxe's correct answer (+1), the following slightly simpler and somewhat more idiomatic XPath will work the same way:
//div[contains(., "Elangovan")]
The reason that your original XPath with text() does not work is that text() will select all text node children of div. However, contains() expects a string in its first argument, and when given a node set of text nodes, it only uses the first one. Here, the first text node contains whitespace, not the sought after string, so the test fails. With the implicit . or the explicit string() first argument, all text node descendants are concatenated together before performing the contains() test, so the test passes.
To make #kjhughes's already good answer just a little more precise, what you're really asking for is a way to look for substrings in the div's string-value:
For every type of node, there is a way of determining a string-value
for a node of that type. For some types of node, the string-value is
part of the node; for other types of node, the string-value is
computed from the string-value of descendant nodes.
Both the context node (. or the div itself) and the set of nodes returned by text() -- or any other argument! -- are first converted to strings when passed to contains. It's just that they're converted in different ways, because one refers to a single element and the other refers to a node-set.
A single element's string-value is the concatenation of the string-values of all its text node descendants. A node-set's string-value, on the other hand, is the string-value of the node in the set that is first in document order.
So the real difference is in what you're converting to a string and how that conversion takes place.