From 327745110a11ae12311c701506e8486d69d39102 Mon Sep 17 00:00:00 2001
From: Dimitri Fontaine <dim@tapoueh.org>
Date: Mon, 18 Jan 2016 21:55:01 +0100
Subject: [PATCH] MySQL bytea default value can be "". Fix 291.

Thanks to a reproducable test case we can see that MySQL default for a
varbinary column is an empty string, so tweak the transform function
byte-vector-to-bytea in order to cope with that.
---
 src/utils/transforms.lisp | 37 ++++++++++++++++++++-----------------
 1 file changed, 20 insertions(+), 17 deletions(-)

diff --git a/src/utils/transforms.lisp b/src/utils/transforms.lisp
index 743a9fc..4e33e66 100644
--- a/src/utils/transforms.lisp
+++ b/src/utils/transforms.lisp
@@ -223,25 +223,28 @@
   http://www.postgresql.org/docs/9.3/interactive/datatype-binary.html
 
   Note that we choose here the bytea Hex Format."
-  (declare (type (or null (simple-array (unsigned-byte 8) (*))) vector))
-  (when vector
-    (let ((hex-digits "0123456789abcdef")
-	  (bytea (make-array (+ 2 (* 2 (length vector)))
-			     :initial-element #\0
-			     :element-type 'standard-char)))
+  (declare (type (or null string (simple-array (unsigned-byte 8) (*))) vector))
+  (etypecase vector
+    (null nil)
+    (string (assert (string= "" vector)) nil)
+    (simple-array
+     (let ((hex-digits "0123456789abcdef")
+           (bytea (make-array (+ 2 (* 2 (length vector)))
+                              :initial-element #\0
+                              :element-type 'standard-char)))
 
-      ;; The entire string is preceded by the sequence \x (to distinguish it
-      ;; from the escape format).
-      (setf (aref bytea 0) #\\)
-      (setf (aref bytea 1) #\x)
+       ;; The entire string is preceded by the sequence \x (to distinguish it
+       ;; from the escape format).
+       (setf (aref bytea 0) #\\)
+       (setf (aref bytea 1) #\x)
 
-      (loop for pos from 2 by 2
-	 for byte across vector
-	 do (let ((high (ldb (byte 4 4) byte))
-		  (low  (ldb (byte 4 0) byte)))
-	      (setf (aref bytea pos)       (aref hex-digits high))
-	      (setf (aref bytea (+ pos 1)) (aref hex-digits low)))
-	 finally (return bytea)))))
+       (loop for pos from 2 by 2
+          for byte across vector
+          do (let ((high (ldb (byte 4 4) byte))
+                   (low  (ldb (byte 4 0) byte)))
+               (setf (aref bytea pos)       (aref hex-digits high))
+               (setf (aref bytea (+ pos 1)) (aref hex-digits low)))
+          finally (return bytea))))))
 
 (defun ensure-parse-integer (string-or-integer)
   "Return an integer value if string-or-integer is an integer or a string