Rails custom validation based on a regex?

Question

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

# A-Z, a-z, 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

molf · Accepted Answer · 2011-10-06 22:02:46Z

17

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.)

edited Oct 6, 2011 at 22:02

answered Oct 6, 2011 at 21:56

molf

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1 Comment

Benjie Over a year ago

Note that using \Z at the end of the regex allows a trailing newline. You probably want \z instead. (Apologies for commenting on an old issue.)

Nikhil · Accepted Answer · 2011-10-06 21:47:05Z

11

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

answered Oct 6, 2011 at 21:47

Nikhil

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1 Comment

vaughanos Over a year ago

This works well for me, however the closing brace is in the incorrect place in this example. It should be: validates :uuid, :format => {:with => /.../i, :message => "..."}

The Whiz of Oz · Accepted Answer · 2016-12-13 08:20:15Z

5

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

edited Dec 13, 2016 at 8:20

The Whiz of Oz

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answered Dec 18, 2015 at 7:05

Nimish

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