$ gem install hatch
Hatch how to certify the attributes of your models, and it will give you the appropriate object.
If you don't hatch your model with all the correct attributes, you'll get an object representing an invalid instance of it.
require 'hatch' class Address include Hatch certify(:street, 'Address must have a street') do |street| !street.nil? && !street.empty? end certify(:number, 'Address must have a positive number') do |number| !number.nil? && number > 0 end end address = Address.hatch(street: 'Fake St', number: 1234) address.class # => Address address.valid? # => true not_an_address = Address.hatch(street: '', number: 1234) not_an_address.class # => Address::InvalidAddress not_an_address.valid? # => false
certify(:attribute, 'error message', &validation) to verify when an attribute is valid.
In case you're wondering, the
Model::InvalidModel is polymorphic with your
Model in all the reader methods declared by
Hatch also supports some common validations we all like to have!
certifies(:attribute, :validation, 'error message') will do the trick.
class Address include Hatch certifies(:street, :not_empty, "This is an error! Where's my street?!") certifies(:number, :positive_number) end
Common validations come in the following flavours (along with default error messages)
'must not be nil'
'must be a positive number'
'must not be empty'
Aaand that's it for the moment. I'll keep on adding more as they come to my mind. If they come to yours first, feel free to add them and PR.
You'll also get a handy
errors hash with a couple of super powers.
not_an_address = Address.hatch(street: '', number: 1234) not_an_address.class # => Address::InvalidAddress not_an_address.errors.full_messages # => ['Address must have a street'] not_an_address.errors.on(:street) # => 'Address must have a street' not_an_address.errors[:number] # =>  not_an_address.errors.empty? # => false
Interesting use cases
Hatch is essentially a validator, so you can rely on it to certify your attributes before they get to the model.
class AddressForm include Hatch certify(:street, 'Address must have a street') do |street| !street.nil? && !street.empty? end certify(:number, 'Address must have a positive number') do |number| !number.nil? && number > 0 end end # Meanwhile, in your favorite Ruby web framework... address_form = AddressForm.hatch(params['address']) if address_form.valid? Address.create(params['address']) else # try again end
One of the nicest things about
Hatch is that errors can be any object of your desire! Power to thy user.
class LowAwesomenessError attr_accessor :code, :message end class Address include Hatch error = LowAwesomenessError.new # => #<LowAwesomenessError:0x007fdb3458eeb0> error.code, error.message = :moar_awesome_plz, 'this is not awesome enough' certifies(:street, :presence, error) end not_an_address = Address.hatch(street: '') not_an_address.errors.on(:street) # => #<LowAwesomenessError:0x007fdb3458eeb0 @code=:moar_awesome_plz, @message="this is not awesome enough">
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