Re: [PATCH] ob-sql.el: Option to reference connections in `sql-connection-alist'

[Stefano Rodighiero <stefano.rodighiero@gmail.com>]

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On Sun, Apr 7, 2019 at 9:24 AM Nicolas Goaziou <mail@nicolasgoaziou.fr>
wrote:

Thank you for your review.
I am attaching a new patch that should address your remarks.
Also, see comments below.


> > +Given a param NAME, if :dbconnection is defined in PARAMS then
> > +look for the param into the corresponding connection defined in
> > +`sql-connection-alist`, otherwise look into PARAMS.  Look
> > +`sql-connection-alist` (part of SQL mode) for how to define
> > +database connections."
> > +  (if (assq :dbconnection params)
> > +      (let* ((dbconnection (cdr (assq :dbconnection params)))
> > +             (name-mapping '((dbhost . sql-server)
> > +                             (dbport . sql-port)
> > +                             (dbuser . sql-user)
> > +                             (dbpassword . sql-password)
> > +                             (database . sql-database)))
> > +             (mapped-name (cdr (assq name name-mapping))))
> > +        (cadr (assq mapped-name
> > +                    (cdr (assoc dbconnection
> > +                                sql-connection-alist)))))
> > +    (cdr (assq name params))))
>
> Isn't there a type mismatch here?
>

I think you are talking about the asymmetry of `cdr' and `cadr'
in the two branches of `if'.
Unfortunately, it's what I need to access `sql-connection-alist'.
This custom's name is IMO a bit misleading. Here a passage
from its documentation:

'''
Each element of the alist is as follows:

  (CONNECTION \(SQL-VARIABLE VALUE) ...)
'''

And here a piece of code from `sql-connect' as defined
in sql.el (here, connect-set is the set of options attached
to a particular connection):

'''
(dolist (vv connect-set)
                  (let ((var (car vv))
                        (val (cadr vv)))
                    (set-default var (eval val))))
'''

regards,
s.


-- 
www.stefanorodighiero.net

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From e810b3b4b9259b708dd37ac04339e2f71e76478a Mon Sep 17 00:00:00 2001
From: Stefano Rodighiero <stefano.rodighiero@gmail.com>
Date: Sun, 24 Mar 2019 11:35:21 +0100
Subject: [PATCH] ob-sql.el: Option to reference connections in
 `sql-connection-alist'

* lisp/ob-sql.el (org-babel-find-db-connection-param): new function.

Provide a new param called :dbconnection, that can be used to
reference connections defined in `sql-connection-alist', a custom
variable defined in sql.el.

TINYCHANGE
---
 lisp/ob-sql.el | 30 +++++++++++++++++++++++++-----
 1 file changed, 25 insertions(+), 5 deletions(-)

diff --git a/lisp/ob-sql.el b/lisp/ob-sql.el
index 2a58188..1007e74 100644
--- a/lisp/ob-sql.el
+++ b/lisp/ob-sql.el
@@ -39,6 +39,7 @@
 ;; - dbport
 ;; - dbuser
 ;; - dbpassword
+;; - dbconnection (to reference connections in sql-connection-alist)
 ;; - database
 ;; - colnames (default, nil, means "yes")
 ;; - result-params
@@ -174,16 +175,35 @@ Otherwise, use Emacs' standard conversion function."
 	((string= "windows-nt" system-type) file)
 	(t (format "%S" (convert-standard-filename file)))))
 
+(defun org-babel-find-db-connection-param (params name)
+  "Return database connection parameter NAME.
+Given a parameter NAME, if :dbconnection is defined in PARAMS
+then look for the parameter into the corresponding connection
+defined in `sql-connection-alist`, otherwise look into PARAMS.
+Look `sql-connection-alist` (part of SQL mode) for how to define
+database connections."
+  (if (assq :dbconnection params)
+      (let* ((dbconnection (cdr (assq :dbconnection params)))
+             (name-mapping '((:dbhost . sql-server)
+                             (:dbport . sql-port)
+                             (:dbuser . sql-user)
+                             (:dbpassword . sql-password)
+                             (:database . sql-database)))
+             (mapped-name (cdr (assq name name-mapping))))
+        (cadr (assq mapped-name
+                    (cdr (assoc dbconnection sql-connection-alist)))))
+    (cdr (assq name params))))
+
 (defun org-babel-execute:sql (body params)
   "Execute a block of Sql code with Babel.
 This function is called by `org-babel-execute-src-block'."
   (let* ((result-params (cdr (assq :result-params params)))
          (cmdline (cdr (assq :cmdline params)))
-         (dbhost (cdr (assq :dbhost params)))
-         (dbport (cdr (assq :dbport params)))
-         (dbuser (cdr (assq :dbuser params)))
-         (dbpassword (cdr (assq :dbpassword params)))
-         (database (cdr (assq :database params)))
+         (dbhost (org-babel-find-db-connection-param params :dbhost))
+         (dbport (org-babel-find-db-connection-param params :dbport))
+         (dbuser (org-babel-find-db-connection-param params :dbuser))
+         (dbpassword (org-babel-find-db-connection-param params :dbpassword))
+         (database (org-babel-find-db-connection-param params :database))
          (engine (cdr (assq :engine params)))
          (colnames-p (not (equal "no" (cdr (assq :colnames params)))))
          (in-file (org-babel-temp-file "sql-in-"))
-- 
2.7.4