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A validator and RSpec matcher for requiring an attachment using Active Storage
class AttachedValidator < ActiveModel::EachValidator
def validate_each(record, attribute, value)
record.errors.add(attribute, :attached, options) unless value.attached?
end
end
en:
activerecord:
errors:
messages:
attached: is not attached
require "rspec/expectations"
RSpec::Matchers.define :validate_attachment_of do |attr_name|
match do |record|
matcher.matches?(record, attr_name)
end
chain :on do |validation_context|
matcher.on(validation_context)
end
chain :with_message do |message|
matcher.with_message(message)
end
private
def matcher
@matcher ||= ValidateAttachmentOfMatcher.new
end
class ValidateAttachmentOfMatcher
def on(validation_context)
@validation_context = validation_context
end
def with_message(message)
@message = message
end
def matches?(record, attr_name)
record.send(attr_name).purge
record.valid?(validation_context)
record.errors[attr_name].include? message
end
private
attr_reader :validation_context
def message
@message || I18n.translate("activerecord.errors.messages.attached")
end
end
end
@rubendinho

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@rubendinho rubendinho commented Sep 25, 2019

Thanks for putting this together. This has worked great for me in Rails 5.2. In Rails 6, you will get an FrozenError: can't modify frozen Hash error from line 32. Instead of purging, the blob should be set to nil.

To fix, that line should be replaced with:

record.send("#{attr_name}=", nil)

An explanation here: rails/rails#37069

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