validation to disallow a single character (<) in Rails

Question

I'd like to disallow the < character in first_name in our model. What would the regex for this be?

I tried

  validates :first_name, format: { with: /[^<]/ }

but doesn't seem to work.

Slightly more correct is `\A` instead of `^` - `\A` is for start of string rather than start of line (even though they should be the same here). https://ruby-doc.org/core-2.5.1/Regexp.html#class-Regexp-label-Anchors — Dave Slutzkin, Jan 18 '19 at 18:43
@DaveSlutzkin the `^` in this case has nothing to do with start of line it is an exclusionary character class e.g. any character except ` — engineersmnky, Jan 18 '19 at 19:54

Matt · Accepted Answer · 2019-01-21T12:36:12.637

2

You can use without instead of with in the validation
You may want to escape the less-than, as zishe suggests, but I don't think this is necessary.

validates :first_name, format: { without: /</ }

https://guides.rubyonrails.org/active_record_validations.html#format

edit: incorporated @engineersmnky points, much simpler.

edited Jan 21 '19 at 12:36

answered Jan 18 '19 at 17:27

Matt

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The "hat" inside a character class means any character **Not** in this class. However the OP's validation will only fail if the **Only** character is `" – engineersmnky Jan 18 '19 at 19:53

score 0 · Answer 2 · answered Jan 18 '19 at 17:29

0

You are currently only capturing the first character. So you probably want to do something like [^<].* (a string starting with anything but < and followed by arbitrary characters)

answered Jan 18 '19 at 17:29

inyono

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validation to disallow a single character (<) in Rails

2 Answers2