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;;; emacsql-pg.el --- back-end for PostgreSQL via pg -*- lexical-binding: t; -*-
;;; Commentary:
;; Unlike emacsql-psql, this connection type uses Eric Marsden's pg.el
;; to connect to PostgreSQL. It speaks directly to the database, so
;; unlike the other EmacSQL connection types, this one requires no
;; external command line programs.
;; The only pg functions required are pg:connect, pg:disconnect,
;; pg:exec, and pg:result. Unfortunately, since pg.el is synchronous
;; it will not be fully compliant once EmacSQL supports asynchronous
;; queries. But, on the plus side, this means the implementation below
;; is dead simple.
;;; Code:
(require 'pg)
(require 'eieio)
(require 'cl-lib)
(require 'cl-generic)
(require 'emacsql)
(require 'emacsql-psql) ; for reserved words
(defclass emacsql-pg-connection (emacsql-connection)
((pgcon :reader emacsql-pg-pgcon :initarg :pgcon)
(dbname :reader emacsql-pg-dbname :initarg :dbname)
(result :accessor emacsql-pg-result)
(types :allocation :class
:reader emacsql-types
:initform '((integer "BIGINT")
(float "DOUBLE PRECISION")
(object "TEXT")
(nil "TEXT"))))
(:documentation "A connection to a PostgreSQL database via pg.el."))
(cl-defun emacsql-pg (dbname user &key
(host "localhost") (password "") (port 5432) debug)
"Connect to a PostgreSQL server using pg.el."
(let* ((pgcon (pg:connect dbname user password host port))
(connection (make-instance 'emacsql-pg-connection
:process (pgcon-process pgcon)
:pgcon pgcon
:dbname dbname)))
(when debug (emacsql-enable-debugging connection))
(emacsql connection [:set (= default-transaction-isolation 'SERIALIZABLE)])
(emacsql-register connection)))
(cl-defmethod emacsql-close ((connection emacsql-pg-connection))
(ignore-errors (pg:disconnect (emacsql-pg-pgcon connection))))
(cl-defmethod emacsql-send-message ((connection emacsql-pg-connection) message)
(condition-case error
(setf (emacsql-pg-result connection)
(pg:exec (emacsql-pg-pgcon connection) message))
(error (signal 'emacsql-error error))))
(cl-defmethod emacsql-waiting-p ((_connection emacsql-pg-connection))
;; pg:exec will block
t)
(cl-defmethod emacsql-parse ((connection emacsql-pg-connection))
(let ((tuples (pg:result (emacsql-pg-result connection) :tuples)))
(cl-loop for tuple in tuples collect
(cl-loop for value in tuple
when (stringp value) collect (read value)
else collect value))))
(provide 'emacsql-pg)
;;; emacsql-pg.el ends here
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