I am not very familiar with regex. I am trying to match routes in ruby. I have a situation where I have some /route/:id that can take the 'id' parameter. I would like to match the route to any string with parameters as long as there is no forward slash. So anything like /route/123 should match but anything like /route/subroute/123 should not since there is a forward slash after 'subroute'. This is my current regex pattern that matches the '/routes/' portion and allows any string to take place of the 'id' parameter: \A\/routes\/\z*. This works, but if a forward slash is present in the 'id' portion of the route, the match still succeeds. What can I do to allow any string as the 'id' as long as a forward slash is not present?
CodePudding user response：
This ended up being the pattern that worked for my case:
^\/route(\/[A-Za-z0-9\-\_]*)?$
Since it is a route, I found it better to allow only valid url characters and I use the parentheses (...)? for cases of routes that do not take parameters at all so '/route', '/route/', and '/route/abc' will all work, but '/route/abc/' will not.
CodePudding user response：
In Ruby, ^ marks the start of any line, not string, so instead of ^, you need \A. Same with $, to match a string end position, you need to use \z.
Also, to match a single path subpart (the string between two slashes here) you can use a negated character class [^\/] / [^\/]*. If you plan to restrict the chars in the subpart to alphanumeric, hyphen and underscore, you can replace [^\/] with [\w-].
So, you can also use
/\A\/route(?:\/[\w-]*)?\z/
Details:
\A- start of string\/route- a literal/routestring(?:\/[\w-]*)?- an optional (due to the last?) non-capturing group that matches an optional sequence of/and then zero or more alphanumeric, underscore (\w) or hyphen chars\z- end of string.
See the Rubular demo (here, ^ and $ are used for demo purposes only since the input is a single multiline text).