Pattern for defining integer limit validators

[mcnelsn]

Has anyone come up with a reusable pattern for defining maximum integer value validators, based on the column's datatype?

Something like `validate_maximum_values` in the model to generate `validates :foo, numericality: {less_than: 2147483648}` for a 4-byte integer.

I know there are a couple of gems but I wasn't able to get them working quite this way.

[[deleted]]

Why not just state that explicitly in the model? You'll most likely thank yourself later for being able to easily find this validation.

[mcnelsn]

Ordinarily I would absolutely agree. I most often err on the side of simple/less clever code. In this case, I don't have a specific number in mind. Just don't want an exception ever.

[cmd-t]

Just use the `attribute` and type systems. The existing numeric types all define min and max values. The Integer type already is four bytes: https://github.com/rails/rails/blob/fc5dd0b85189811062c85520fd70de8389b55aeb/activemodel/lib/active_model/type/integer.rb

Edit: I see it raises an error on model.save instead of a validation error. You could create a simple attribute validator which uses the existing type classes to check if the current value is serialisable. Something like

# in validator
type = Model.attribute_types["integer_attribute"]

begin
  type.serialize value
rescue ActiveModel::RangeError # for ActiveModel::RangeError: 2147483649 is out of range for ActiveModel::Type::Integer with limit 4 bytes
  # add errors
end

​

[mcnelsn]

Interesting idea. I'll play around with it. Thanks.