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.

1 files changed, 15 insertions, 3 deletions

diff --git a/lisp/progmodes/sql.el b/lisp/progmodes/sql.el
index a11d4560aed..4d0bed77d56 100644
--- a/lisp/progmodes/sql.el
+++ b/lisp/progmodes/sql.el
@@ -1072,14 +1072,26 @@ add your name with a \"-U\" prefix (such as \"-Umark\") to the list."
   :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"