IIS Url Rewite: Add Trailing Slash, Preserve Anchors and Query Strings - regex

Question

I've searched several SO posts and haven't found what I'm looking for. It might exists but might be fairly old enough to not show up for me. I found a post (Nginx rewrite: add trailing slash, preserve anchors and query strings) so close to what I need, but it's regex solution does not work for URL Rewrite for IIS, unless I'm doing it wrong.
Problem
I'm trying to add a forward slash / to the end of my url paths while also preserving any existing for query strings ? and anchors #.
Desired Solution
Basically, here's the desired results to each problem:
Entry: https://my.site.com/about
Result: https://my.site.com/about/
Entry: https://my.site.com/about?query=string
Result: https://my.site.com/about/?query=string
Entry: https://my.site.com/about#TestAnchor
Result: https://my.site.com/about/#TestAnchor
Entry: https://my.site.com/about?query=string#TestAnchor
Result: https://my.site.com/about/?query=string#TestAnchor
Current Tests
Our current regex ignores query strings and anchors, but I would like to take them into consideration now.
<rule name="AddTrailingSlash" stopProcessing="true">
<match url="^([^.?]+[^.?/])$" />
<action type="Redirect" url="{R:1}/" redirectType="Permanent" />
</rule>
I've also tested another regex but it only works if the url contains both a query string AND an anchor.
<rule name="AddTrailingSlash" stopProcessing="true">
<match url="^(.*)(\?.*?)(\#.*?)$" />
<action type="Redirect" url="{R:1}/{R:2}{R:3}" redirectType="Permanent" />
</rule>
NOTE: I just tested this last one (^(.*)(\?.*?)(\#.*?)$) and it actually doesn't work. If the url already contains a / before the ? the test passes which it should not, so I have more work to do here.
Question
Is there a single regex that I can use to solve this or do I need to use multiple rules?

Answer 1

TL;DR
IIS Rewrite (ALL) URIs with Trailing Slash & preserve Fragment and Query Strings
<rule name="AddTrailingSlash" stopProcessing="true">
<match url="^([^/]+:\/\/[^/#?]+|[^?#]+?)\/?((?:[^/?#]+\.[^/?#]+)?(?:[?#].*)?$)" />
<action type="Redirect" url="{R:1}/{R:2}" redirectType="Permanent" />
</rule>
IIS use ECMAScript so you can Try it here : https://regexr.com/6ele7
Update
IIS Rewrite (Considered) URIs with Trailing Slash & preserve Fragment and Query Strings
<rule name="AddTrailingSlash" stopProcessing="true">
<match url="^([^/]+:\/\/[^/#?]+|[^?#]+\/[^/.?#]+)([?#].*)?$" />
<action type="Redirect" url="{R:1}/{R:2}" redirectType="Permanent" />
</rule>
Try it here : https://regexr.com/6fk3g
http://127.0.0.1 --> http://127.0.0.1/
https://localhost --> https://localhost/
https://localhost? --> https://localhost/?
https://localhost/ --> https://localhost/
https://my.site.com --> https://my.site.com/
https://my.site.com:443? --> https://my.site.com:443/?
https://my.site.com/ --> https://my.site.com/
https://my.site.com/about.php --> https://my.site.com/about.php
https://my.site.com/about.php? --> https://my.site.com/about.php?
https://my.site.com/about --> https://my.site.com/about/
https://my.site.com/about? --> https://my.site.com/about/?
https://my.site.com/about/ --> https://my.site.com/about/
https://my.site.com/about/? --> https://my.site.com/about/?
https://my.site.com/about?query --> https://my.site.com/about/?query
https://my.site.com/about/?query --> https://my.site.com/about/?query
https://my.site.com/about.php?query --> https://my.site.com/about.php?query
https://my.site.com/about#hash --> https://my.site.com/about/#hash
https://my.site.com/about/#hash --> https://my.site.com/about/#hash
https://my.site.com/about.php#hash --> https://my.site.com/about.php#hash
https://my.site.com/about?query#hash --> https://my.site.com/about/?query#hash
https://my.site.com/about/?query#hash --> https://my.site.com/about/?query#hash
https://my.site.com/folder.name/about?query --> https://my.site.com/folder.name/about/?query
https://my.site.com/about?query#hash:http://test.com?q --> https://my.site.com/about/?query#hash:http://test.com?q
Explaination (All)
Level 1 - Lets just think about your examples:
^([^?#]+?)\/?([?#].*)?$
Group #1: ^ In first, [^?#] Any character except ?/#, Go much but lazy +? (Stop on first possible, by looking to next)
Ignore: \/? Then if a / exist or not
Group #2: [?#] = ?/# And .* Any much character next to that till $ End, (...)? If exist
It work well. But it will deal not right with:
https://my.site.com/about.php?query --> https://my.site.com/about.php/?query !!!
So let's add an exception...
Level 2 - How if we take possible file name Name.name.name.ext as Group #2?
^([^?#]+?)\/?((?:[^/?#]+\.[^/?#]+)?(?:[?#].*)?)$
(?:...) Non-Capturing group
([^/?#]+\.[^/?#]+)? Look for any possible file name or (?:[?#].*)? Any possible query or anchor strings
Now everything is OK, except this:
https://my.site.com? --> https://my.site.com? !!!
So we need another exception in Group #1
Level 3 - Take just domain URI as an alternative
^([^/]+:\/\/[^/#?]+|[^?#]+?)\/?((?:[^/?#]+\.[^/?#]+)?(?:[?#].*)?$)
(...|...) Alternative
[^/]+:\/\/[^/#?]+ First check if (not lazy) any pattern like ...://... till not / # ? exist?
Now it work great!
+ Explaination (Considered)
Level 4 - How if we just add a Not-Accepting . & / character set in first group to just match considered URIs and ignore others?
^([^/]+:\/\/[^/#?]+|[^?#]+\/[^/.?#]+)([?#].*)?$
\/[^/.?#]+ Check if after last / the set of characters be not /.?#
Now it is even smaller and faster!
Analyzing other method
As #károly-szabó answered well here, instead of looking for Not-Accepted character sets, we can look for matched pattern.
So if we want to use the method but in simpler way (2 Groups) (+ Some minor optimization), the regex will be:
^(https?:\/\/[\w.:-]+\/?(?:[\w.-]+\/)*[\w-]+(?!\/))([?#].*)?$
But URI path Accepted characters are more.
So a wider version of that Regex can be:
^(https?:\/\/[\w.:-]+\/?(?:[\w!#-)+-.;=#~]+\/)*[\w!#-);=#~+,-]+(?!\/))([?#].*)?$
Try it here: https://regexr.com/6elea
Note: Still "multibyte Unicode as domain name is allowed" but i ignored that in this method.
P.S.
Actually i don't think that we should rewrite it on IIS, because of these reasons:
Anchors char # can be part of a folder name (by %23)
A file name can have no extension
IIS/Browsers usually will (/should) handle Anchors/Queries
Ref:
IIS: UrlRewrite middleware query strings are preserved
Google/Anchor tags are stripped from URLs
RFC URI References
URI Wiki
How does IIS URL Rewrite handle # anchor tags
I Mean:
https://my.site.com/ --> (=Call root)
https://my.site.com/about --> (=Call root > Folder/File name about)
https://my.site.com/about/ --> (=Call root > Folder name about)
https://my.site.com/about?query --> (=Call root > Folder/File name about + Query)
https://my.site.com/about/?query --> (=Call root > Folder name about + Query)
https://my.site.com/about.php?query --> (=Call root > File name about.php + Query)
[When browser strip it:]
https://my.site.com/about#hash --> (=Call root > Folder/File name about + Anchor)
https://my.site.com/about/#hash --> (=Call root > Folder name about + Anchor)
https://my.site.com/about.php#hash --> (=Call root > File name about.php + Anchor)
[If not?]
https://my.site.com/folder#name/?query#hash
https://my.site.com/folder.name/about.php?query=one/two

Answer 2

You can try with this regex https://regex101.com/r/6TSqaP/2. This is matching every provided example and solves the problem if the url already has an ending '/'.
^((?:https?:\/\/[\w\.\-]*)(?:[\w\-]+\/)*(?:[\w\-]+)(?!\/))(\?.*?)?(\#.*?)?$
I used your second example as base for my regex, with the following logic.
The parts of the url: scheme://authority/path?query#fragment
first capture group matches the scheme://authority/path part of the url
second capture group optional and matching the ?query
third capture group also optional and for the #fragment
regex explanation
^( # should start with this
(?:https?:\/\/[\w\.\-]*) # match the http or https protocol and the domain
(?:[\w\-]+\/)* # match the path except the last element of it (optional)
(?:[\w\-]+)(?!\/) # match the last path element, but only if it's not closed with '/'
) # {R:1}
(\?.*?)? # {R:2} query (optional)
(\#.*?)? # {R:3} fragment (optional)
$ # string should end
Nginx
<rule name="AddTrailingSlash" stopProcessing="true">
<match url="^((?:https?:\/\/[\w\.\-]*)(?:[\w\-]+\/)*(?:[\w\-]+)(?!\/))(\?.*?)?(\#.*?)?$" />
<action type="Redirect" url="{R:1}/{R:2}{R:3}" redirectType="Permanent" />
</rule>
Edit: Updated regex to handle dashes (-) and multiple path elements