Rails custom validation based on a regex?

I have the following regex that I use in my routes.rb for /type-in-something-here

# A-Z, a-z,开发者_开发知识库 0-9, _ in the middle but never starting or ending in a _
# At least 5, no more than 500 characters

In the routes this works well as:

match ':uuid' => 'room#show', :constraints => { :uuid => /[A-Za-z\d]([-\w]{,498}[A-Za-z\d])?/ }

I want to have this also as a validation so invalid records aren't created. So I added the following to room.rb:

validates_format_of :uuid, :with => /[A-Za-z\d]([-\w]{,498}[A-Za-z\d])?/i, :message => "Invalid! Alphanumerics only."

But this validates_format_of isn't working, and instead of adding an error it's allow the record to save.

Any ideas what's wrong?

Thanks

For validation purposes, remember to add the beginning and end of string markers \A and \Z:

validates_format_of :uuid, :with => /\A[A-Za-z\d]([-\w]{,498}[A-Za-z\d])?\Z/i

Otherwise your regex will happily match any string that contains at least a letter or a digit. For some reason Rails implicitly adds the boundaries in the routes. (Probably because it embeds the regex inside a larger one to match the entire URL, with explicit checks for / and the end of the URL.)

using something like this

validates :uuid, :format => {:with => /[A-Za-z\d]([-\w]{,498}[A-Za-z\d])?/i},
                 :message => "your message"

For more check this

validates :name, format: { with: /\A[a-zA-Z]+\z/,
message: "Only letters are allowed" }