From 439dff974d868b564f660e444b348ad7f61a7989 Mon Sep 17 00:00:00 2001
From: Daniele Varrazzo <daniele.varrazzo@gmail.com>
Date: Sat, 13 Oct 2018 00:47:04 +0100
Subject: [PATCH] Added ConnectionInfo.error_message

---
 doc/src/extensions.rst   |  1 +
 psycopg/conninfo_type.c  | 24 ++++++++++++++++++++++++
 tests/test_connection.py | 12 ++++++++++++
 3 files changed, 37 insertions(+)

diff --git a/doc/src/extensions.rst b/doc/src/extensions.rst
index 9cef3d68..f15c4c1d 100644
--- a/doc/src/extensions.rst
+++ b/doc/src/extensions.rst
@@ -182,6 +182,7 @@ introspection etc.
         of digits is always ``00``. For example, version 9.3.5 will be
         returned as ``90305``, version 10.2 as ``100002``.
 
+    .. autoattribute:: error_message
 
 
 .. class:: Column
diff --git a/psycopg/conninfo_type.c b/psycopg/conninfo_type.c
index 134bb864..4dbaef2b 100644
--- a/psycopg/conninfo_type.c
+++ b/psycopg/conninfo_type.c
@@ -238,6 +238,28 @@ server_version_get(connInfoObject *self)
 }
 
 
+static const char error_message_doc[] =
+"The error message most recently generated by an operation on the connection.\n"
+"\n"
+"`!None` if there is no current message.\n"
+"\n"
+".. seealso:: libpq docs for `PQerrorMessage()`__ for details.\n"
+".. __: https://www.postgresql.org/docs/current/static/libpq-status.html"
+    "#LIBPQ-PQERRORMESSAGE";
+
+static PyObject *
+error_message_get(connInfoObject *self)
+{
+    const char *val;
+
+    val = PQerrorMessage(self->conn->pgconn);
+    if (!val || !val[0]) {
+        Py_RETURN_NONE;
+    }
+    return conn_text_from_chars(self->conn, val);
+}
+
+
 static struct PyGetSetDef connInfoObject_getsets[] = {
     { "dbname", (getter)dbname_get, NULL, (char *)dbname_doc },
     { "user", (getter)user_get, NULL, (char *)user_doc },
@@ -252,6 +274,8 @@ static struct PyGetSetDef connInfoObject_getsets[] = {
         (char *)protocol_version_doc },
     { "server_version", (getter)server_version_get, NULL,
         (char *)server_version_doc },
+    { "error_message", (getter)error_message_get, NULL,
+        (char *)error_message_doc },
     {NULL}
 };
 
diff --git a/tests/test_connection.py b/tests/test_connection.py
index 06735fbb..3d678573 100755
--- a/tests/test_connection.py
+++ b/tests/test_connection.py
@@ -1752,6 +1752,18 @@ class TestConnectionInfo(ConnectingTestCase):
 
         self.assertEqual(self.bconn.info.server_version, 0)
 
+    def test_error_message(self):
+        self.assertIsNone(self.conn.info.error_message)
+        self.assertIsNotNone(self.bconn.info.error_message)
+
+        cur = self.conn.cursor()
+        try:
+            cur.execute("select 1 from nosuchtable")
+        except psycopg2.DatabaseError:
+            pass
+
+        self.assert_('nosuchtable' in self.conn.info.error_message)
+
 
 def test_suite():
     return unittest.TestLoader().loadTestsFromName(__name__)