Rails custom route with constraints - regexp anchor characters are not allowed in routing requirements

问题

I have the following route:

  get 'users/:user_id/:name', to: 'profiles#show',
    :constraints => { :name => /[a-zA-Z0-9_]+$/ }, as: 'user_profile'

Which produces the error:

Regexp anchor characters are not allowed in routing requirements: /[a-zA-Z0-9_]+$/

So I get that the ^ character isn't allowed, but not sure what character is producing this particular routing error.

回答1:

In regex we have two anchors:

1. Beginning of line/string ^
2. End of line/string $

---

Try to remove $ from the pattern and you should be good to go...

回答2:

The regex anchors are ^ and $, but they don't achieve anything here. "(Y)ou don’t need to use anchors because all routes are anchored at the start.".

So the constraint:

:constraints => { :name => /[a-zA-Z0-9_]+/ }

will do what you want - ensure the name is composed of 1 or more of those characters, and nothing else. BTW you can simplify the regex:

:constraints => { :name => /\w+/ }

来源：https://stackoverflow.com/questions/13222382/rails-custom-route-with-constraints-regexp-anchor-characters-are-not-allowed-i