Add connection.get_dsn_parameters()

doc/src/connection.rst

@@ -568,6 +568,24 @@ The ``connection`` class
         .. versionadded:: 2.0.12
 
 
+    .. method:: get_dsn_parameters()
+
+        Get the effective dsn parameters for the connection as a dictionary.
+
+        The *password* parameter is removed from the result.
+
+        Example::
+
+            >>> conn.get_dsn_parameters()
+            {'dbname': 'test', 'user': 'postgres', 'port': '5432', 'sslmode': 'prefer'}
+
+        Requires libpq >= 9.3.
+
+        .. seealso:: libpq docs for `PQconninfo()`__ for details.
+
+            .. __: http://www.postgresql.org/docs/current/static/libpq-connect.html#LIBPQ-PQCONNINFO
+
+
     .. index::
         pair: Transaction; Status
 

psycopg/connection_type.c

@@ -733,6 +733,37 @@ psyco_conn_get_parameter_status(connectionObject *self, PyObject *args)
     return conn_text_from_chars(self, val);
 }
 
+/* get_dsn_parameters method - Get connection parameters */
+
+#define psyco_conn_get_dsn_parameters_doc \
+"get_dsn_parameters() -- Get effective connection parameters.\n\n"
+
+static PyObject *
+psyco_conn_get_dsn_parameters(connectionObject *self)
+{
+#if PG_VERSION_NUM >= 90300
+    PyObject *res = NULL;
+    PQconninfoOption *options = NULL;
+
+    EXC_IF_CONN_CLOSED(self);
+
+    if (!(options = PQconninfo(self->pgconn))) {
+        PyErr_NoMemory();
+        goto exit;
+    }
+
+    res = psycopg_dict_from_conninfo_options(options, /* include_password = */ 0);
+
+exit:
+    PQconninfoFree(options);
+
+    return res;
+#else
+    PyErr_SetString(NotSupportedError, "PQconninfo not available in libpq < 9.3");
+    return NULL;
+#endif
+}
+
 
 /* lobject method - allocate a new lobject */
 
@@ -977,6 +1008,8 @@ static struct PyMethodDef connectionObject_methods[] = {
      METH_NOARGS, psyco_conn_get_transaction_status_doc},
     {"get_parameter_status", (PyCFunction)psyco_conn_get_parameter_status,
      METH_VARARGS, psyco_conn_get_parameter_status_doc},
+    {"get_dsn_parameters", (PyCFunction)psyco_conn_get_dsn_parameters,
+     METH_NOARGS, psyco_conn_get_dsn_parameters_doc},
     {"get_backend_pid", (PyCFunction)psyco_conn_get_backend_pid,
      METH_NOARGS, psyco_conn_get_backend_pid_doc},
     {"lobject", (PyCFunction)psyco_conn_lobject,

psycopg/psycopg.h

@@ -131,6 +131,9 @@ STEALS(1) HIDDEN PyObject * psycopg_ensure_bytes(PyObject *obj);
 
 STEALS(1) HIDDEN PyObject * psycopg_ensure_text(PyObject *obj);
 
+HIDDEN PyObject *psycopg_dict_from_conninfo_options(PQconninfoOption *options,
+              int include_password);
+
 /* Exceptions docstrings */
 #define Error_doc \
 "Base class for error exceptions."

psycopg/psycopgmodule.c

@@ -118,8 +118,8 @@ static PyObject *
 psyco_parse_dsn(PyObject *self, PyObject *args, PyObject *kwargs)
 {
     char *err = NULL;
-    PQconninfoOption *options = NULL, *o;
+    PQconninfoOption *options = NULL;
-    PyObject *dict = NULL, *res = NULL, *dsn;
+    PyObject *res = NULL, *dsn;
 
     static char *kwlist[] = {"dsn", NULL};
     if (!PyArg_ParseTupleAndKeywords(args, kwargs, "O", kwlist, &dsn)) {
@@ -140,26 +140,10 @@ psyco_parse_dsn(PyObject *self, PyObject *args, PyObject *kwargs)
         goto exit;
     }
 
-    if (!(dict = PyDict_New())) { goto exit; }
+    res = psycopg_dict_from_conninfo_options(options, /* include_password = */ 1);
-    for (o = options; o->keyword != NULL; o++) {
-        if (o->val != NULL) {
-            PyObject *value;
-            if (!(value = Text_FromUTF8(o->val))) { goto exit; }
-            if (PyDict_SetItemString(dict, o->keyword, value) != 0) {
-                Py_DECREF(value);
-                goto exit;
-            }
-            Py_DECREF(value);
-        }
-    }
-
-    /* success */
-    res = dict;
-    dict = NULL;
 
 exit:
     PQconninfoFree(options);    /* safe on null */
-    Py_XDECREF(dict);
     Py_XDECREF(dsn);
 
     return res;

psycopg/utils.c

@@ -247,3 +247,32 @@ psycopg_is_text_file(PyObject *f)
     }
 }
 
+/* Make a dict out of PQconninfoOption array */
+PyObject *
+psycopg_dict_from_conninfo_options(PQconninfoOption *options, int include_password)
+{
+    PyObject *dict, *res = NULL;
+    PQconninfoOption *o;
+
+    if (!(dict = PyDict_New())) { goto exit; }
+    for (o = options; o->keyword != NULL; o++) {
+        if (o->val != NULL &&
+            (include_password || strcmp(o->keyword, "password") != 0)) {
+            PyObject *value;
+            if (!(value = Text_FromUTF8(o->val))) { goto exit; }
+            if (PyDict_SetItemString(dict, o->keyword, value) != 0) {
+                Py_DECREF(value);
+                goto exit;
+            }
+            Py_DECREF(value);
+        }
+    }
+
+    res = dict;
+    dict = NULL;
+
+exit:
+    Py_XDECREF(dict);
+
+    return res;
+}

tests/test_connection.py

@@ -381,6 +381,12 @@ class ParseDsnTestCase(ConnectingTestCase):
         self.assertRaises(TypeError, parse_dsn, None)
         self.assertRaises(TypeError, parse_dsn, 42)
 
+    def test_get_dsn_paramaters(self):
+        conn = self.connect()
+        d = conn.get_dsn_parameters()
+        self.assertEqual(d['dbname'], dbname)  # the only param we can check reliably
+        self.assertNotIn('password', d)
+
 
 class IsolationLevelsTestCase(ConnectingTestCase):