Enum, ActiveModel and I18n

[Sadjow Leão]

Hi folks,

I'm thinking about a Pull Request for Rails. But, I want to validate with you.

Why not put Enum into ActiveModel? We may need some enumeration into another model without ActiveRecord, a example: something like a mail object form with a enumeration for subject... and other situations.

And a second Pull Request is:

i18n for enum values. We need that.

What do you think about?

Thanks,

[Rafael Mendonça França]

Hi,

Could you explain a bit more about the use case you are thinking for enum feature on Active Model?

By what you described I believe you can reach with validates_inclusion_of and a hash. An example of the controller and view would help.

Also, could you also explain what is the use case for i18n for enum values?

Rafael Mendonça França
http://twitter.com/rafaelfranca
https://github.com/rafaelfranca

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[Sadjow Leão]

Hi Rafael,

I think that as ActiveModel holds the attributes, it can hold the enums. Enums are like attributes, but with a pre-defined collection of values( enum is a special kind of attribute). And not only ActiveRecord objects can have enumerations. I think that this is natural of a model and not only of a record of database.

With enum attribute in ActiveModel, we can take advantage of the same API of enums for create objects like Form Objects, ValueObjects(ActiveModel) and etc ..... With this, we can extend the use of enums`s API.

That way, we can have a conversion for the translations(humanization) of enumerations:

A example of a YML file with the enum values translations that we could access by  example a method `Employee.type.human`:

A method called Employee.type.collection could return the collection with translated humanized values, that can be used by a select box in a form.

--

Sadjow Medeiros Leão

Software Engineer

http://about.me/sadjow

http://www.linkedin.com/pub/sadjow-le%C3%A3o/16/1/966

[T.J. Schuck]

> Why not put Enum into ActiveModel? We may need some enumeration into another model without ActiveRecord, a example: something like a mail object form with a enumeration for subject…

If the object isn’t persisted to the DB, it doesn’t seem like you’d need to use AR::Enum — the primary benefit is that it maps the options to integers in the DB column.  For a non-persisted model, you can just use a regular attribute with an inclusion validation like Rafael mentioned.

> By what you described I believe you can reach with validates_inclusion_of and a hash.

Note that AR::Enum doesn’t play nicely with `inclusion` validations — see https://github.com/rails/rails/issues/13971 — so this only applies to the provided workaround for a  non-persisted object.

[Sadjow Leão]

Yeap, T.J.

But, actually enums are not only for persisted AR objects, we can find enumerations where we can have a pre-defined list of values.

A validation doesn't matter here. I'need the same enum API for a model.

Without this behaviour in ActiveModel, we will end up making a similar behaviour of enums to accomplish this need.

Sadjow Medeiros Leão

Software Engineer

http://github.com/sadjow

http://www.linkedin.com/pub/sadjow-le%C3%A3o/16/1/966

[Rafael Mendonça França]

Could you please provide a concrete example of what you need from enum feature? How would you like to use?

Rafael Mendonça França
http://twitter.com/rafaelfranca
https://github.com/rafaelfranca