Enums and STI

[Zac Moody]

Hi all,

I was thinking that someone might want the type column used with Single-Table Inheritance to be an Enum rather than a string.  Is the counter argument that STI is responsible for the type column so it doesn't matter?

If the inheritance_column did support enum, would the resulting code be repeating itself too much?  

class User < ActiveRecord::Base

  enum type: [:student, :teacher]

end

class Teacher < User

end

class Student < User

end

If there's interest in this feature I would be happy to work on adding it.

Zac

[Tomas Varneckas]

Hi,

We have a project at my workplace which heavily relies on a custom in-house extension to ActiveRecord which does this

(but ofcourse in an uglier way). It'd be great if this was a builtin feature.

Hardcoding class names in table rows makes for tedious migrations whenever classes are renamed.

Good luck! :)

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[Zac Moody]

Of course, if this was implemented then polymorphic association `_type` fields should also support Enums for consistency.  I think this would be advantageous for the same reasons.

[Matt Jones]

On May 8, 2014, at 12:25 PM, Tomas Varneckas <t.var...@gmail.com> wrote:

Hi,

We have a project at my workplace which heavily relies on a custom in-house extension to ActiveRecord which does this

(but ofcourse in an uglier way). It'd be great if this was a builtin feature.

Hardcoding class names in table rows makes for tedious migrations whenever classes are renamed.

I’m not sure that a call to `update_all` really counts as “tedious”:

StiBaseClass.where(type: ‘OldType’).update_all(type: ‘NewType’)

The biggest issue I see with using enums for this is that the possible values of an enum need to be listed *someplace* - reflecting on all the subclasses of StiBaseClass won’t work since the order isn’t stable under renaming.

This applies doubly to using enums in polymorphic association _type fields…

—Matt Jones