Normally, the result of a pg-exec
query is an object from which Scheme
strings can be extracted to represent the datum from a particular tuple/field
coordinate, using pg-getvalue
(see Retrieving Data). If this
string is sufficient for your needs, you can skip this chapter, which
describes how to use the PostgreSQL-to-Scheme (and back) type conversion
support installed with Guile-PG, including how to register new converters.
To get started, load the postgres-types
module:
(use-modules (database postgres-types))
But before we get to conversions, recall that the pg-ftype
example
(see Processing Results)
defines a procedure that returns the name of a PostgreSQL type by doing a
query on the pg_type
(internal) table. Here is a more efficient
implementation:
(define CONN (pg-connectdb ...)) (define (pg-ftype-name result fnum) (assq-ref (oid-type-name-cache CONN) (pg-ftype result fnum)))
It uses a bonus procedure in this module: