How can I replace all instances of a match with itself and more? Ruby

Question

Ok, so say I have a bunch of inputs in an HTML file like this:

<input class="form-control" type="text" id="ogwb">
<input class="form-control" type="text" id="aosgh">
<input class="form-control" type="text" id="aghw">

How can I replace all instances of the ids with themselves and a name and value attribute having the same id value like so:

<input class="form-control" type="text" id="ogwb" name="ogwb" value="<?php echo htmlspecialchars($_POST['ogwb']); ?>">
<input class="form-control" type="text" id="aosgh" name="aosgh" value="<?php echo htmlspecialchars($_POST['aosgh']); ?>">
<input class="form-control" type="text" id="aghw" name="aghw" value="<?php echo htmlspecialchars($_POST['aghw']); ?>">

This is what I've tried:

f = File.read('my.html')
$arr = f.scan(/id="([^"]*)"/)

$arr.each{ |a|
    e_ = a.join(", ")+'"'
    e__ = a.join(", ")+'"'+' name="'+a.join(", ")+'" value="<?php echo htmlspecialchars($_POST['+"'"+a.join(", ")+"'"+']); ?>"'
    f.gsub(/#{e_}/,e__)
}

Which if I do puts e_ and puts e__ I get the match and replace I want, but gsub doesn't seem to work.

https://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags — bjhaid, Oct 14 '16 at 03:58
Use something like [nokogiri](http://www.nokogiri.org/) instead — bjhaid, Oct 14 '16 at 03:59

Addison · Answer 1 · 2016-10-14T03:46:44.440

1

You will want to use regex to grab this:

<input class="form-control" type="text" id="([^"]+)">

Notice that I surrounded the text value of the id with a capturing group (the brackets). This is capture group #1.

You can access the first captured group with \1.

So you'll want to search for the previous regex, and replace it with the following:

<input class="form-control" type="text" id="\1" name="\1" value="<?php echo htmlspecialchars($_POST['\1']); ?>">

Demonstration: https://regex101.com/r/qeHkmg/1

Documentation: http://www.regular-expressions.info/replacebackref.html

edited Oct 14 '16 at 03:46

answered Oct 14 '16 at 03:41

Addison

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Make sure you escape the ``\``'s with more ``\``'s when using gsub. – Addison Oct 14 '16 at 04:13

How can I replace all instances of a match with itself and more? Ruby

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