Rails, validate maxlength of input field

Question

I have a comment model where I limit the maximum length of a comment like:

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validates_length_of :comment, :maximum => 500

In my view I have input field declared:

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<%= f.text_area :comment,:as => :text, :maxlength => 500 %>

The limit on the input field works as expected, it limits to maximum 500 chars.

However, the model limit does not work as expected. A text of 500 chars with newlines gives a validation error. The model counts newlines as two characters (and possible other characters too). So

This input will work, no newlines:

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 abc abc abc abc....

This will not:

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abc

abc
.
.

Is there a simple way to make validates_length_of to count newlines (and other) as one character?.

===Result1===

I combined the great answers from Jon and Dario and created this:

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before_validation(:on => :create) do
  self.comment = comment.gsub("\r\n","\n") if self.comment
end

Answer 1

Browsers send newlines from textareas as "\r\n" Effectively each newline is counted as two chars when using Rails default length validator

So either make a replace method in the controller, or make a custom length validator.

Answer 2

You could use tokenizer option of the length validator, to count only the words, not the line breaks.

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validates :comment, length: {
  maximum: 500,
  tokenizer: lambda { |str| str.scan(/\w+/) }
}

For more information, take a look here: Active Record Validations and Callbacks