Rails 4 - Validate Elements in Array

Question

One of my models contains a virtual attribute called things. This attribute is an array, and I'd like every element within that array to be validated against a set of rules. Here is my current attempt at validation:

validates :things, presence: true,  length: { minimum: 2, maximum: 255 }

The problem with this code is that it validates the entire array itself, not each individual element within the array. I know I can write a custom validator, but is there any way to use the existing validation options to run these validations against every element in the array? The other topics I found on this are for older versions of Rails, so I'm not sure if Rails 4 has something new that could help with this.

Thanks in advance for any help!

Demi Magus · Accepted Answer · 2015-07-25 03:55:14Z

1

Have you tried a custom validation? You can create a custom validation inside your model.

Something like this, where "things" is the name of the attribute that you want to validate:

model.rb

validate :check_each_thing

def check_each_thing
  things.each do |thing|
    if thing.present?
      if thing.size < 2 || thing.size > 255
        errors.add(:things, 'It should be longer than 2 and shorter than 255.')
      end
    else
      errors.add(:things, 'It should be present.')
    end
  end
end

Hope it helps :)

answered Jul 25, 2015 at 3:55

Demi Magus

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1 Comment

Alexander Over a year ago

Hi Demi, thank you for the answer! As I mentioned in my question, I know I can write a custom validator, but I wanted to see if there is another way to accomplish this. It seems like this is my only option. Thank you for the help!

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