bug#24646: [PATCH] Complete the name of PostgreSQL databases

["Simen Heggestøyl" <simenheg@gmail.com>]

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Thank you for your detailed feedback, Michael.

I agree with all of your points and have modified the patch accordingly,
except for one:

On Mon, Nov 7, 2016 at 5:03 AM, Michael Mauger <michael@mauger.com> 
wrote:
> * `dolist' can specify the return value rather than having a separate 
> expression after the loop. That is, (dolist (row (process-lines ...) 
> (nreverse res)) ...)) is equivalent to (dolist (row (process-lines 
> ...)) ...) (nreverse res)

I'm aware of it, but I tend to avoid using it, since I have many times
myself overlooked it when reading code that uses it. If it's OK with you
I'll leave it like it is, but if you insist I can change it.

> * I'm concerned about the change to the `completing-read' call in 
> `sql-get-login-ext'. Rather than `nil', I'd suggest `confirm' so that 
> if the value isn't in the list, it must be confirmed.
> * If the REQUIRE-MATCH parameter should really be something other 
> than `t', then possibbly we should add another keyword 
> :completion-required whose value would be used in the 
> `completing-read' call (default to `t' to preserve current 
> functionality).

It's not important to me. I made the change because I thought it could
be frustrating for the user if `sql-postgres-list-databases' doesn't
work as it should, but I realize now that changing it probably deserves
a discussion and a patch on its own.

-- Simen

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From b26312bc9000f8ec39a525eefad5f0c93c767b86 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simen=20Heggest=C3=B8yl?= <simenheg@gmail.com>
Date: Thu, 6 Oct 2016 20:42:53 +0200
Subject: [PATCH] Complete the name of PostgreSQL databases

* lisp/progmodes/sql.el (sql-postgres-login-params): Complete database
name.
(sql-postgres-list-databases): New function returning a list of
available PostgreSQL databases.

* test/lisp/progmodes/sql-tests.el: New file with tests for sql.el.
---
 lisp/progmodes/sql.el            | 18 ++++++++++++---
 test/lisp/progmodes/sql-tests.el | 47 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 62 insertions(+), 3 deletions(-)
 create mode 100644 test/lisp/progmodes/sql-tests.el

diff --git a/lisp/progmodes/sql.el b/lisp/progmodes/sql.el
index a11d456..4d0bed7 100644
--- a/lisp/progmodes/sql.el
+++ b/lisp/progmodes/sql.el
@@ -1072,14 +1072,26 @@ sql-postgres-options
   :version "20.8"
   :group 'SQL)
 
-(defcustom sql-postgres-login-params `((user :default ,(user-login-name))
-                                       (database :default ,(user-login-name))
-                                       server)
+(defcustom sql-postgres-login-params
+  `((user :default ,(user-login-name))
+    (database :default ,(user-login-name)
+              :completion ,(completion-table-dynamic
+                            (lambda (_) (sql-postgres-list-databases))))
+    server)
   "List of login parameters needed to connect to Postgres."
   :type 'sql-login-params
   :version "24.1"
   :group 'SQL)
 
+(defun sql-postgres-list-databases ()
+  "Return a list of available PostgreSQL databases."
+  (when (executable-find sql-postgres-program)
+    (let ((res '()))
+      (dolist (row (process-lines sql-postgres-program "-ltX"))
+        (when (string-match "^ \\([[:alnum:]-_]+\\) +|.*" row)
+          (push (match-string 1 row) res)))
+      (nreverse res))))
+
 ;; Customization for Interbase
 
 (defcustom sql-interbase-program "isql"
diff --git a/test/lisp/progmodes/sql-tests.el b/test/lisp/progmodes/sql-tests.el
new file mode 100644
index 0000000..e05247a
--- /dev/null
+++ b/test/lisp/progmodes/sql-tests.el
@@ -0,0 +1,47 @@
+;;; sql-tests.el --- Tests for sql.el  -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2016 Free Software Foundation, Inc.
+
+;; Author: Simen Heggestøyl <simenheg@gmail.com>
+;; Keywords:
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;;
+
+;;; Code:
+
+(require 'cl-lib)
+(require 'ert)
+(require 'sql)
+
+(ert-deftest sql-tests-postgres-list-databases ()
+  "Test that output from `psql -ltX' is parsed correctly."
+  (cl-letf
+      (((symbol-function 'executable-find)
+        (lambda (_command) t))
+       ((symbol-function 'process-lines)
+        (lambda (_program &rest _args)
+          '(" db-name-1 | foo-user | UTF8     | en_US.UTF-8 | en_US.UTF-8 | "
+            " db_name_2 | foo-user | UTF8     | en_US.UTF-8 | en_US.UTF-8 | "
+            ""))))
+    (should (equal (sql-postgres-list-databases)
+                   '("db-name-1" "db_name_2")))))
+
+(provide 'sql-tests)
+;;; sql-tests.el ends here
-- 
2.10.2