How do I abandon validations after single (important) failure? - ruby-on-rails

Question

I have a class with some validations:
class HeyThere < ActiveRecord::Base
validate :check_something
validate :check_something_property_1
validate :check_something_property_2
validate :check_something_property_3
def check_something
errors.add(:something, "not there") if something.nil?
end
def check_something_property_1
errors.add(:something, "bad property 1") if something.property_1 > 10
end
def check_something_property_2
errors.add(:something, "bad property 2") if something.property_2 == "ha!"
end
def check_something_property_3
errors.add(:something, "bad property 3") if something.property_3
end
end
The problem is, if something doesn't exist, the first validation triggers, but the second one throws an exception:
undefined method `property_1' for nil:NilClass
For the example, I gave general examples for the validations, but in reality, they are fairly complex. I could change each one to if something && something.property_N whatever, but that feels hacky, and makes the code less-readable, plus, its not very DRY when the number of validations becomes larger.
Is there a way to cancel the remaining validations if the first one fails?

Answer 1

Since they depend on each other, these shouldn't be separate validations. Do this:
class PastaRecipe < ActiveRecord::Base
validate :have_ingredients
private
def have_ingredients
# Don't run the remaining validations if any one validation fails.
have_pasta &&
have_sauce &&
have_water
end
def have_pasta
errors.add(:pasta, "need to buy pasta!") unless pasta.purchased?
end
def have_sauce
errors.add(:sauce, "need delicious sauce!") unless sauce.delicious?
end
def have_water
errors.add(:water, "need to boil water!") unless water.boiled?
end
end

Answer 2

Since you don't want to use if-else statements, I suggest using raise to halt the entire validation chain:
class HeyThere < ActiveRecord::Base
validate :check_something
validate :check_something_property_1
validate :check_something_property_2
validate :check_something_property_3
def check_something
if something.nil?
errors.add(:something, "not there")
raise ActiveRecord::RecordInvalid, self
end
end
def check_something_property_1
errors.add(:something, "bad property 1") if something.property_1 > 10
end
def check_something_property_2
errors.add(:something, "bad property 2") if something.property_2 == "ha!"
end
def check_something_property_3
errors.add(:something, "bad property 3") if something.property_3
end
end

Answer 3

I did something like this. I'm just using the validations module here, but it applies to active record models the same way. There are a lot of different modifications that can be done to this, but this is almost the exact implementation I used.
Must list validations in order
Can be modified to halt on any error including instance.errors[:base]
Can halt on ANY error using instance.errors.any?
with_options method will actually pass the "unless: Proc" to each validation, so it actually
runs for each validation
with_options can be replaced by just putting if or unless conditions on each validation
Class definition. Non-AR version. Same can be done with ActiveRecord::Base classes
class Skippy
# wouldnt need to do this initialize on the ActiveRecord::Base model version
include ActiveModel::Validations
validate :first
validate :second
validate :halt_on_third
validates_presence_of :or_halt_on_fourth
with_options unless: Proc.new{ |instance| [:halt_on_thirds_error_key, :or_halt_on_fourth].any?{ |key| instance.errors[key].any? } } do |instance|
instance.validate :wont_run_fifth
instance.validates_presence_of :and_wont_run_sixth
end
# wouldn't need to do these on the ActiveRecord::Base model version
attr_accessor :attributes
def initialize
#attributes = { or_halt_on_fourth: "I'm here" }
end
def read_attribute_for_validation(key)
#attributes[key]
end
def first
errors.add :base, 'Base error from first'
end
def second
errors.add :second, 'Just an error'
end
def halt_on_third
errors.add :halt_on_thirds_error_key, 'Halting error' unless #donthalt
end
def wont_run_fifth
errors.add :wont_run_fifth, 'ran because there were no halting errors'
end
end
Demo
2.0.0 :040 > skippy = Skippy.new
=> #<Skippy:0x0000000d98c1c0 #attributes={:or_halt_on_fourth=>"I'm here"}>
2.0.0 :041 > skippy.errors.any?
=> false
2.0.0 :042 > skippy.valid?
=> false
2.0.0 :043 > skippy.errors.full_messages
=> ["Base error from first", "Second Just an error", "Halt on thirds error key Halting error"]
2.0.0 :044 > skippy.errors.clear
=> {}
2.0.0 :045 > skippy.instance_variable_set(:#donthalt, true)
=> true
2.0.0 :046 > skippy.errors.any?
=> false
2.0.0 :047 > skippy.valid?
=> false
2.0.0 :048 > skippy.errors.full_messages
=> ["Base error from first", "Second Just an error", "Wont run fifth ran because there were no halting errors", "And wont run sixth can't be blank"]
2.0.0 :049 > skippy.errors.clear; skippy.attributes = {}; skippy.errors.any?
=> false
2.0.0 :050 > skippy.valid?; skippy.errors.full_messages
=> ["Base error from first", "Second Just an error", "Or halt on fourth can't be blank"]
2.0.0 :051 >