CODEWITHSUNDEEP
ruby-on-railspaperclip
user1887348
user1887348

Reputation: 339

Correct validating uniqueness of uploaded images which allows posting without uploading

I want to allow posting either messages without images or with a unique image, I added following code in my model

validates :image_fingerprint, :uniqueness => true

It forbids posting similar images but it forbids as well posting more than one message without image. I tried to add

:allow_blank => true

and

:allow_nil => true

but it leads to the following error:

TypeError in PostsController#create can't convert nil into String

How can I fix it?

Upvotes: 1

Views: 244

Answers (1)

Billy Chan
Billy Chan

Reputation: 24815

You can use :unless on validation, only if this attribute not blank

validates :image_fingerprint, :uniqueness => true, 
  :unless => Proc.new { |a| a.image_fingerprint.blank? }

Reference:

You can associate the :if and :unless options with a symbol corresponding to the name of a method that will get called right before validation happens. This is the most commonly used option.

Finally, it’s possible to associate :if and :unless with a Proc object which will be called. Using a Proc object gives you the ability to write an inline condition instead of a separate method. This option is best suited for one-liners.

http://guides.rubyonrails.org/active_record_validations_callbacks.html#conditional-validation

Upvotes: 2

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