Re: Working with PostgreSQL enums in C code

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Fri, May 28, 2010 at 12:07 AM, Joseph Adams
> <joeyadams3(dot)14159(at)gmail(dot)com> wrote:
>> I learned that to return an enum value from C, one needs to return the
>> OID of the right row of the pg_enum table. I eventually managed to
>> write the code below, which is mostly based on the enum_in function in
>> src/backend/utils/adt/enum.c .

> PG_RETURN macros shouldn't do any nontrivial processing (see the
> existing ones for references).

Yeah, that was my first reaction too. If we don't already have one,
it would be appropriate to provide a "lookup enum value" function
(functionally about the same as enum_in, but designed to be called
conveniently from C). Then, if you needed to work from a textual
enum label, you'd call that function and then PG_RETURN_OID.

However, for a built-in enum type, I agree with Robert's solution of
just #define-ing fixed OIDs for the values of the type.

regards, tom lane