I have a bunch of records in a QuickBase table that contain a rich text field. In other words, they each contain some paragraphs of text intermingled with HTML tags like <p>, <strong>, etc.
I need to migrate the records to a new table where the corresponding field is a plain text field. For this, I would like to strip out all HTML tags and leave only the text in the field values.
For example, from the below input, I would expect to extract just a small example link to a webpage:
<p>just a small <a href="#">
example</a> link</p><p>to a webpage</p>
As I am trying to get this done quickly and without coding or using an external tool, I am constrained to using Quickbase Pipelines' Text channel tool. The way it works is that I define a regex pattern and it outputs only the bits that match the pattern.
So far I've been able to come up with this regular expression (Python-flavored as QB's backend is written in Python) that correctly does the exact opposite of what I need. I.e. it matches only the HTML tags:
/(<[^>]*>)/
In a sense, I need the negative image of this expression but have not be able to build it myself.
Your help in "negating" the above expression is most appreciated.
Assuming there are no < or > elsewhere or entity-encoded, an idea using a lookbehind.
(?:(?<=>)|^)[^<]+
See this demo at regex101
(?:(?<=>)|^) is an alternation between either ^ start of the string or looking behind for any >. From there [^<]+ matches one or more characters that are not < (negated character class).
I would like to replace the text in a google doc. At the moment I have place markers as follows
Invoice ##invoiceNumber##
I replace the invoice number with
body.replaceText('##invoiceNumber##',invoiceNumber);
Which is fine but I can only run the script once as obviously ##invoiceNumber## is no longer in the document. I was thinking I could replace the text after Invoice as this will stay the same, appendParagraph looks like it might to the trick but I can't figure it out. I think something like body.appendParagraph("Invoice") would select the area? Not sure how to append to this after that.
You could try something like this I think:
body.replaceText('InvoiceNumber \\w{1,9} ','InvoiceNumber ' + invoicenumber);
I don't know how big your invoice numbers are but that will except from 1 to 9 word characters preceeded by a space and followed by a space. That pattern might have to be modified depending upon your textual needs.
Word Characters [A-Za-z0-9_]
If your invoice numbers are unique enough perhaps you could just replace them.
Reference
Regular Expression Syntax
Note: the regex pattern is passed as a string rather than a regular expression
I have a single text field that contains HTML markup. The system that generates this field content always seems to generate a first line with a non-visible carriage return value in it and I can't seem to prevent if from doing so.
Does anyone know of a way (perhaps using a Regular Expression), to remove that first line from this text field?
I'd prefer to leave all other instances of the carriage return values in the field as is, so if it's a RegEx statement that will just remove the first line of a text field, that would work for me.
Any suggestions most welcomed.
Cheers,
Wayne
Usually the trim (often removes whitespaces, CR ) method is used for this in many programming languages. You did not state in what language you will be doing this...
I am creating an application that will take a URL as input, retrieve the page's html content off the web and extract everything that isn't contained in a tag. In other words, the textual content of the page, as seen by the visitor to that page. That includes 'masking' out everything encapsuled in <script></script>, <style></style> and <!-- -->, since these portions contain text that is not enveloped within a tag (but is best left alone).
I have constructed this regex:
(?:<(?P<tag>script|style)[\s\S]*?</(?P=tag)>)|(?:<!--[\s\S]*?-->)|(?:<[\s\S]*?>)
It correctly selects all the content that i want to ignore, and only leaves the page's text contents. However, that means that what I want to extract won't show up in the match collection (I am using VB.Net in Visual Studio 2010).
Is there a way to "invert" the matching of a whole document like this, so that I'd get matches on all the text strings that are left out by the matching in the above regex?
So far, what I did was to add another alternative at the end, that selects "any sequence that doesn't contain < or >", which then means the leftover text. I named that last bit in a capture group, and when I iterate over the matches, I check for the presence of text in the "text" group. This works, but I was wondering if it was possible to do it all through regex and just end up with matches on the plain text.
This is supposed to work generically, without knowing any specific tags in the html. It's supposed to extract all text. Additionally, I need to preserve the original html so the page retains all its links and scripts - i only need to be able to extract the text so that I can perform searches and replacements within it, without fear of "renaming" any tags, attributes or script variables etc (so I can't just do a "replace with nothing" on all the matches I get, because even though I am then left with what I need, it's a hassle to reinsert that back into the correct places of the fully functional document).
I want to know if this is at all possible using regex (and I know about HTML Agility Pack and XPath, but don't feel like).
Any suggestions?
Update:
Here is the (regex-based) solution I ended up with: http://www.martinwardener.com/regex/, implemented in a demo web application that will show both the active regex strings along with a test engine which lets you run the parsing on any online html page, giving you parse times and extracted results (for link, url and text portions individually - as well as views where all the regex matches are highlighted in place in the complete HTML document).
what I did was to add another alternative at the end, that selects "any sequence that doesn't contain < or >", which then means the leftover text. I named that last bit in a capture group, and when I iterate over the matches, I check for the presence of text in the "text" group.
That's what one would normally do. Or even simpler, replace every match of the markup pattern with and empty string and what you've got left is the stuff you're looking for.
It kind of works, but there seems to be a string here and there that gets picked up that shouldn't be.
Well yeah, that's because your expression—and regex in general—is inadequate to parse even valid HTML, let alone the horrors that are out there on the real web. First tip to look at, if you really want to chase this futile approach: attribute values (as well as text content in general) may contain an unescaped > character.
I would like to once again suggest the benefits of HTML Agility Pack.
ETA: since you seem to want it, here's some examples of markup that looks like it'll trip up your expression.
<a href=link></a> - unquoted
<a href= link></a> - unquoted, space at front matched but then required at back
- very common URL char missing in group
- more URL chars missing in group
<a href=lïnk></a> - IRI
<a href
="link"> - newline (or tab)
<div style="background-image: url(link);"> - unquoted
<div style="background-image: url( 'link' );"> - spaced
<div style="background-image: url('link');"> - html escape
<div style="background-image: ur\l('link');"> - css escape
<div style="background-image: url('link\')link');"> - css escape
<div style="background-image: url(\
'link')"> - CSS folding
<div style="background-image: url
('link')"> - newline (or tab)
and that's just completely valid markup that won't match the right link, not any of the possible invalid markup, markup that shouldn't but does match a link, or any of the many problems with your other technique of splitting markup from text. This is the tip of the iceberg.
Regex is not reliable for retrieving textual contents of HTML documents. Regex cannot handle nested tags. Supposing a document doesn't contain any nested tag, regex still requires every tags are properly closed.
If you are using PHP, for simplicity, I strongly recommend you to use DOM (Document Object Model) to parse/extract HTML documents. DOM library usually exists in every programming language.
If you're looking to extract parts of a string not matched by a regex, you could simply replace the parts that are matched with an empty string for the same effect.
Note that the only reason this might work is because the tags you're interested in removing, <script> and <style> tags, cannot be nested.
However, it's not uncommon for one <script> tag to contain code to programmatically append another <script> tag, in which case your regex will fail. It will also fail in the case where any tag isn't properly closed.
You cannot parse HTML with regular expressions.
Parsing HTML with regular expressions leads to sadness.
I know you're just doing it for fun, but there are so many packages out there than actually do the parsing the right way, AND do it reliably, AND have been tested.
Don't go reinventing the wheel, and doing it a way that is all but guaranteed to frustrate you down the road.
OK, so here's how I'm doing it:
Using my original regex (with the added search pattern for the plain text, which happens to be any text that's left over after the tag searches are done):
(?:(?:<(?P<tag>script|style)[\s\S]*?</(?P=tag)>)|(?:<!--[\s\S]*?-->)|(?:<[\s\S]*?>))|(?P<text>[^<>]*)
Then in VB.Net:
Dim regexText As New Regex("(?:(?:<(?<tag>script|style)[\s\S]*?</\k<tag>>)|(?:<!--[\s\S]*?-->)|(?:<[\s\S]*?>))|(?<text>[^<>]*)", RegexOptions.IgnoreCase)
Dim source As String = File.ReadAllText("html.txt")
Dim evaluator As New MatchEvaluator(AddressOf MatchEvalFunction)
Dim newHtml As String = regexText.Replace(source, evaluator)
The actual replacing of text happens here:
Private Function MatchEvalFunction(ByVal match As Match) As String
Dim plainText As String = match.Groups("text").Value
If plainText IsNot Nothing AndAlso plainText <> "" Then
MatchEvalFunction = match.Value.Replace(plainText, plainText.Replace("Original word", "Replacement word"))
Else
MatchEvalFunction = match.Value
End If
End Function
Voila. newHtml now contains an exact copy of the original, except every occurrence of "Original word" in the page (as it's presented in a browser) is switched with "Replacement word", and all html and script code is preserved untouched. Of course, one could / would put in a more elaborate replacement routine, but this shows the basic principle. This is 12 lines of code, including function declaration and loading of html code etc. I'd be very interested in seeing a parallel solution, done in DOM etc for comparison (yes, I know this approach can be thrown off balance by certain occurrences of some nested tags quirks - in SCRIPT rewriting - but the damage from that will still be very limited, if any (see some of the comments above), and in general this will do the job pretty darn well).
For Your Information,
Instead of Regex, With JQuery , Its possible to extract text alone from a html markup. For that you can use the following pattern.
$("<div/>").html("#elementId").text()
You can refer this JSFIDDLE
I have a problem creating a regular expression for the following task:
Suppose we have HTML-like text of the kind:
<x>...<y>a</y>...<y>b</y>...</x>
I want to get a collection of values inside <y></y> tags located inside a given <x> tag, so the result of the above example would be a collection of two elements ["a","b"].
Additionally, we know that:
<y> tags cannot be enclosed in other <y> tags
... can include any text or other tags.
How can I achieve this with RegExp?
This is a job for an HTML/XML parser. You could do it with regular expressions, but it would be very messy. There are examples in the page I linked to.
I'm taking your word on this:
"y" tags cannot be enclosed in other "y" tags
input looks like: <x>...<y>a</y>...<y>b</y>...</x>
and the fact that everything else is also not nested and correctly formatted. (Disclaimer: If it is not, it's not my fault.)
First, find the contents of any X tags with a loop over the matches of this:
<x[^>]*>(.*?)</x>
Then (in the loop body) find any Y tags within match group 1 of the "outer" match from above:
<y[^>]*>(.*?)</y>
Pseudo-code:
input = "<x>...<y>a</y>...<y>b</y>...</x>"
x_re = "<x[^>]*>(.*?)</x>"
y_re = "<y[^>]*>(.*?)</y>"
for each x_match in input.match_all(x_re)
for each y_match in x_match.group(1).value.match_all(y_re)
print y_match.group(1).value
next y_match
next x_match
Pseudo-output:
a
b
Further clarification in the comments revealed that there is an arbitrary amount of Y elements within any X element. This means there can be no single regex that matches them and extracts their contents.
Short and simple: Use XPath :)
It would help if we knew what language or tool you're using; there's a great deal of variation in syntax, semantics, and capabilities. Here's one way to do it in Java:
String str = "<y>c</y>...<x>...<y>a</y>...<y>b</y>...</x>...<y>d</y>";
String regex = "<y[^>]*+>(?=(?:[^<]++|<(?!/?+x\\b))*+</x>)(.*?)</y>";
Matcher m = Pattern.compile(regex).matcher(str);
while (m.find())
{
System.out.println(m.group(1));
}
Once I've matched a <y>, I use a lookahead to affirm that there's a </x> somewhere up ahead, but there's no <x> between the current position and it. Assuming the pseudo-HTML is reasonably well-formed, that means the current match position is inside an "x" element.
I used possessive quantifiers heavily because they make things like this so much easier, but as you can see, the regex is still a bit of a monster. Aside from Java, the only regex flavors I know of that support possessive quantifiers are PHP and the JGS tools (RegexBuddy/PowerGrep/EditPad Pro). On the other hand, many languages provide a way to get all of the matches at once, but in Java I had to code my own loop for that.
So it is possible to do this job with one regex, but a very complicated one, and both the regex and the enclosing code have to be tailored to the language you're working in.