Posted over 10 years ago. Visible to the public. Repeats.

Copying validation errors from one attribute to another

When using virtual attributes, the attached trait can be useful to automatically copy errors from one attribute to another.

Here is a typical use case where Paperclip creates a virtual attribute :attachment, but there are validations on both :attachment and :attachment_file_name. If the form has a file picker on :attachment, you would like to highlight it with errors from any attribute:

class Note < ActiveRecord::Base has_attached_file :attachment validates_attachment_presence :attachment validates_format_of :attachment_file_name, :with => /^\d+\.jpg$/ include DoesCopyErrors[from: :attachment_file_name, to: :attachment] end

If you'd like to remove the errors from the source attribute once they are copied to the target attribute, you can use the :move option:

include DoesCopyErors[from: :attachment_file_name, to: :attachment, move: true]

By refactoring problematic code and creating automated tests, makandra can vastly improve the maintainability of your Rails application.

Owner of this card:

Henning Koch
Last edit:
3 months ago
by Jakob Scholz
About this deck:
We are makandra and do test-driven, agile Ruby on Rails software development.
License for source code
Posted by Henning Koch to makandra dev
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