Negate regex of validates_format_of

Question

In my rails model I have some kind of template system. I want to make sure that users editing it do not make accidental mistakes so I use some simple validators.

They can use markers like ##user_id## that will be replaced later. I want to make sure they do not enter something like ###user_id## that contains too many #, so not any ### (or ####) must appear in the field.

class Template
  validates_format_of :text, :with => /##user_id##/, 
    :message => "##user_id## must be present"
  validates_format_of :text, :not_with => /###/, 
    :message => "Too many #"
end

Unfortunately there is no :not_with option ... is there any chance to solve it using a :with-regex or should I go a separate validate method?

I tried some negative look-ahead, but as there are (mostly) several ## and only one ### they always match one of them.

Miscreant · Accepted Answer · 2013-10-24 20:39:06Z

4

Use the :without option:

validates_format_of :text, :without => /###/, :message => "Too many #"

answered Oct 24, 2013 at 20:39

Miscreant

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Comments

Kyle · Accepted Answer · 2012-06-26 15:18:05Z

1

What about this...

validates_format_of :text, :with => /(^|[^#])##user_id##($|[^#])/

EDIT: I copied acheong87's rubular examples with my regex.

answered Jun 26, 2012 at 15:18

Kyle

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Comments

Andrew Cheong · Accepted Answer · 2012-06-26 15:18:51Z

0

Can you do something like this?

    /^(.(?!###+user_id##|##user_id###+))*$/

Here's a live demo: http://rubular.com/r/SPwsyDlj0y.

In (more) English, it says,

A string in which no character is followed by ###+user_id## or ##user_id###+.

answered Jun 26, 2012 at 15:18

Andrew Cheong

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1 Comment

arnep Over a year ago

This is some kind of query I tried before, but unfortunately it is not working with the validates_format_of

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