Support PostgreSQL enum, please :) about squeryl

[max-l]

Question: should database enums be maped by Scala enums, Int, maybe both should be supported ?

[dimgel]

Maybe Scala enums or strings. Int is inconvenient: statement "create type t as enum('a', 'b', 'c')" contains symbolic names, not ints.

[max-l]

Ok, I think both needs to be supported then, I need to find out how Scala enums work
internally, I mean how they can be set/get by reflection. Do you know ?
Another thing is that some DBs don't support enums, so we have to see if a
"lowest common denominator" can be good in all cases.

[dimgel]

Do you know ?

Unfortunately no.

lowest common denominator

No much help from me here either. The first idea - it's String because enum value maybe converted to string, and before Postgres supported enums, they were emulated with text + check constraint.

But the problem is about declaration. If class field is declared as string, how would you know it must be casted to enum? Where would you get enum's name from? Maybe annotation is needed here which provides enum (generally - any custom type) name.

For example, if you see:
@enum("kind_enum") kind: String
or:
@type("kind_enum") kind: String

then in SQL you generate:
cast(kind as kind_enum)

It was just draft idea.

[dflemstr]

To reflect on Enumerations, you can use "classOf[MyEnumeration#Value]" to gain access to the class, if you want to access information about individual value alternatives.

Enumeration values can be gotten via "MyEnumeration.values" (The "MyEnumeration" object can be accessed reflexively like any other singleton object, by e.g. appending "$" to the name).

Every Enumeration value has an id: Int. This is the common denominator for Enumerations, at least. You can also get enumeration values by id and map each enumeration value to a string.

I don't see how this is any more or less difficult than mapping any other kind of value to a database...

[max-l]

Fixed as of 0.9.4-RC1
http://github.com/max-l/Squeryl/commit/e2daa20d51034b5810dca9923f6ffba85df05fe5