Work-in-progress support for retrieving PG_DIAG result error fields.

psycopg/diagnostics.h

@@ -0,0 +1,38 @@
+/* diagnostics.c - definition for the psycopg Diagnostics type
+ *
+ * Copyright (C) 2013 Matthew Woodcraft <matthew@woodcraft.me.uk>
+ *
+ * This file is part of psycopg.
+ *
+ * psycopg2 is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * In addition, as a special exception, the copyright holders give
+ * permission to link this program with the OpenSSL library (or with
+ * modified versions of OpenSSL that use the same license as OpenSSL),
+ * and distribute linked combinations including the two.
+ *
+ * You must obey the GNU Lesser General Public License in all respects for
+ * all of the code used other than OpenSSL.
+ *
+ * psycopg2 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 Lesser General Public
+ * License for more details.
+ */
+
+#ifndef PSYCOPG_DIAGNOSTICS_H
+#define PSYCOPG_DIAGNOSTICS_H 1
+
+extern HIDDEN PyTypeObject diagnosticsType;
+
+typedef struct {
+    PyObject_HEAD
+
+    PyObject *err;           /* exception to retrieve the diagnostics from */
+
+} diagnosticsObject;
+
+#endif /* PSYCOPG_DIAGNOSTICS_H */

psycopg/diagnostics_type.c

@@ -0,0 +1,204 @@
+/* diagnostics.c - present information from libpq error responses
+ *
+ * Copyright (C) 2013 Matthew Woodcraft <matthew@woodcraft.me.uk>
+ *
+ * This file is part of psycopg.
+ *
+ * psycopg2 is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * In addition, as a special exception, the copyright holders give
+ * permission to link this program with the OpenSSL library (or with
+ * modified versions of OpenSSL that use the same license as OpenSSL),
+ * and distribute linked combinations including the two.
+ *
+ * You must obey the GNU Lesser General Public License in all respects for
+ * all of the code used other than OpenSSL.
+ *
+ * psycopg2 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 Lesser General Public
+ * License for more details.
+ */
+
+#define PSYCOPG_MODULE
+#include "psycopg/psycopg.h"
+
+#include "psycopg/diagnostics.h"
+#include "psycopg/cursor.h"
+
+/* These are new in PostgreSQL 9.3. Defining them here so that psycopg2 can
+ * use them with a 9.3+ server even if compiled against pre-9.3 headers. */
+#ifndef PG_DIAG_SCHEMA_NAME
+#define PG_DIAG_SCHEMA_NAME     's'
+#endif
+#ifndef PG_DIAG_TABLE_NAME
+#define PG_DIAG_TABLE_NAME      't'
+#endif
+#ifndef PG_DIAG_COLUMN_NAME
+#define PG_DIAG_COLUMN_NAME     'c'
+#endif
+#ifndef PG_DIAG_DATATYPE_NAME
+#define PG_DIAG_DATATYPE_NAME   'd'
+#endif
+#ifndef PG_DIAG_CONSTRAINT_NAME
+#define PG_DIAG_CONSTRAINT_NAME 'n'
+#endif
+
+
+/* Retrieve an error string from the exception's cursor.
+ *
+ * If the cursor or its result isn't available, return None.
+ */
+static PyObject *
+psyco_diagnostics_get_field(diagnosticsObject *self, void *closure)
+{
+    // closure contains the field code.
+    PyObject *rv = NULL;
+    PyObject *curs = NULL;
+    const char* errortext;
+    if (!(curs = PyObject_GetAttrString(self->err, "cursor")) ||
+        !PyObject_TypeCheck(curs, &cursorType) ||
+        ((cursorObject *)curs)->pgres == NULL) {
+        goto exit;
+    }
+    errortext = PQresultErrorField(
+        ((cursorObject *)curs)->pgres, (Py_intptr_t) closure);
+    if (errortext) {
+        // FIXME: does this need to use conn_text_from_chars()?
+        rv = PyString_FromString(errortext);
+    }
+exit:
+    if (!rv) {
+        rv = Py_None;
+        Py_INCREF(rv);
+    }
+    Py_XDECREF(curs);
+    return rv;
+}
+
+
+/* object calculated member list */
+static struct PyGetSetDef diagnosticsObject_getsets[] = {
+    { "schema_name", (getter)psyco_diagnostics_get_field, NULL,
+      NULL, (void*) PG_DIAG_SCHEMA_NAME },
+    { "table_name", (getter)psyco_diagnostics_get_field, NULL,
+      NULL, (void*) PG_DIAG_TABLE_NAME },
+    { "column_name", (getter)psyco_diagnostics_get_field, NULL,
+      NULL, (void*) PG_DIAG_COLUMN_NAME },
+    { "datatype_name", (getter)psyco_diagnostics_get_field, NULL,
+      NULL, (void*) PG_DIAG_DATATYPE_NAME },
+    { "constraint_name", (getter)psyco_diagnostics_get_field, NULL,
+      NULL, (void*) PG_DIAG_CONSTRAINT_NAME },
+    {NULL}
+};
+
+/* initialization and finalization methods */
+
+static int
+diagnostics_setup(diagnosticsObject *self, PyObject *err)
+{
+    self->err = err;
+    Py_INCREF(err);
+
+    return 0;
+}
+
+static void
+diagnostics_dealloc(PyObject* obj)
+{
+    diagnosticsObject *self = (diagnosticsObject *)obj;
+
+    Py_XDECREF(self->err);
+
+    Py_TYPE(obj)->tp_free(obj);
+}
+
+static int
+diagnostics_init(PyObject *obj, PyObject *args, PyObject *kwds)
+{
+    PyObject *err = NULL;
+
+    if (!PyArg_ParseTuple(args, "O", &err))
+        return -1;
+
+    return diagnostics_setup((diagnosticsObject *)obj, err);
+}
+
+static PyObject *
+diagnostics_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    return type->tp_alloc(type, 0);
+}
+
+static void
+diagnostics_del(PyObject* self)
+{
+    PyObject_Del(self);
+}
+
+
+/* object type */
+
+#define diagnosticsType_doc \
+"Details from a database error report."
+
+PyTypeObject diagnosticsType = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "psycopg2._psycopg.Diagnostics",
+    sizeof(diagnosticsObject),
+    0,
+    diagnostics_dealloc, /*tp_dealloc*/
+    0,          /*tp_print*/
+    0,          /*tp_getattr*/
+    0,          /*tp_setattr*/
+    0,          /*tp_compare*/
+    0,          /*tp_repr*/
+    0,          /*tp_as_number*/
+    0,          /*tp_as_sequence*/
+    0,          /*tp_as_mapping*/
+    0,          /*tp_hash */
+
+    0,          /*tp_call*/
+    0,          /*tp_str*/
+    0,          /*tp_getattro*/
+    0,          /*tp_setattro*/
+    0,          /*tp_as_buffer*/
+
+    Py_TPFLAGS_DEFAULT|Py_TPFLAGS_BASETYPE, /*tp_flags*/
+    diagnosticsType_doc, /*tp_doc*/
+
+    0,          /*tp_traverse*/
+    0,          /*tp_clear*/
+
+    0,          /*tp_richcompare*/
+    0,          /*tp_weaklistoffset*/
+
+    0,          /*tp_iter*/
+    0,          /*tp_iternext*/
+
+    /* Attribute descriptor and subclassing stuff */
+
+    0,          /*tp_methods*/
+    0,          /*tp_members*/
+    diagnosticsObject_getsets, /*tp_getset*/
+    0,          /*tp_base*/
+    0,          /*tp_dict*/
+
+    0,          /*tp_descr_get*/
+    0,          /*tp_descr_set*/
+    0,          /*tp_dictoffset*/
+
+    diagnostics_init, /*tp_init*/
+    0, /*tp_alloc  will be set to PyType_GenericAlloc in module init*/
+    diagnostics_new, /*tp_new*/
+    (freefunc)diagnostics_del, /*tp_free  Low-level free-memory routine */
+    0,          /*tp_is_gc For PyObject_IS_GC */
+    0,          /*tp_bases*/
+    0,          /*tp_mro method resolution order */
+    0,          /*tp_cache*/
+    0,          /*tp_subclasses*/
+    0           /*tp_weaklist*/
+};

psycopg/pqpath.c

@@ -1509,7 +1509,8 @@ pq_fetch(cursorObject *curs, int no_result)
     default:
         Dprintf("pq_fetch: uh-oh, something FAILED: pgconn = %p", curs->conn);
         pq_raise(curs->conn, curs, NULL);
-        IFCLEARPGRES(curs->pgres);
+        /* don't clear curs->pgres, because it contains detailed error
+           information */
         ex = -1;
         break;
     }

psycopg/psycopgmodule.c

@@ -35,6 +35,7 @@
 #include "psycopg/typecast.h"
 #include "psycopg/microprotocols.h"
 #include "psycopg/microprotocols_proto.h"
+#include "psycopg/diagnostics.h"
 
 #include "psycopg/adapter_qstring.h"
 #include "psycopg/adapter_binary.h"
@@ -500,6 +501,7 @@ psyco_errors_init(void)
     PyObject *base;
     PyObject *str = NULL;
     PyObject *descr = NULL;
+    PyObject *diag_property = NULL;
     int rv = -1;
 
 #if PY_VERSION_HEX >= 0x02050000
@@ -541,6 +543,12 @@ psyco_errors_init(void)
     PyObject_SetAttrString(Error, "pgcode", Py_None);
     PyObject_SetAttrString(Error, "cursor", Py_None);
 
+    if (!(diag_property = PyObject_CallFunctionObjArgs(
+            (PyObject *) &PyProperty_Type, &diagnosticsType, NULL))) {
+        goto exit;
+    }
+    PyObject_SetAttrString(Error, "diag", diag_property);
+
     /* install __reduce_ex__ on Error to make all the subclasses picklable.
      *
      * Don't install it on Py 2.4: it is not used by the pickle
@@ -560,6 +568,7 @@ psyco_errors_init(void)
     rv = 0;
 
 exit:
+    Py_XDECREF(diag_property);
     Py_XDECREF(descr);
     Py_XDECREF(str);
     Py_XDECREF(dict);
@@ -882,6 +891,7 @@ INIT_MODULE(_psycopg)(void)
     Py_TYPE(&chunkType)      = &PyType_Type;
     Py_TYPE(&NotifyType)     = &PyType_Type;
     Py_TYPE(&XidType)        = &PyType_Type;
+    Py_TYPE(&diagnosticsType) = &PyType_Type;
 
     if (PyType_Ready(&connectionType) == -1) goto exit;
     if (PyType_Ready(&cursorType) == -1) goto exit;
@@ -898,6 +908,7 @@ INIT_MODULE(_psycopg)(void)
     if (PyType_Ready(&chunkType) == -1) goto exit;
     if (PyType_Ready(&NotifyType) == -1) goto exit;
     if (PyType_Ready(&XidType) == -1) goto exit;
+    if (PyType_Ready(&diagnosticsType) == -1) goto exit;
 
 #ifdef PSYCOPG_EXTENSIONS
     Py_TYPE(&lobjectType)    = &PyType_Type;
@@ -987,6 +998,7 @@ INIT_MODULE(_psycopg)(void)
     PyModule_AddObject(module, "ISQLQuote", (PyObject*)&isqlquoteType);
     PyModule_AddObject(module, "Notify", (PyObject*)&NotifyType);
     PyModule_AddObject(module, "Xid", (PyObject*)&XidType);
+    PyModule_AddObject(module, "Diagnostics", (PyObject*)&diagnosticsType);
 #ifdef PSYCOPG_EXTENSIONS
     PyModule_AddObject(module, "lobject", (PyObject*)&lobjectType);
 #endif
@@ -1031,6 +1043,7 @@ INIT_MODULE(_psycopg)(void)
     pydatetimeType.tp_alloc = PyType_GenericAlloc;
     NotifyType.tp_alloc = PyType_GenericAlloc;
     XidType.tp_alloc = PyType_GenericAlloc;
+    diagnosticsType.tp_alloc = PyType_GenericAlloc;
 
 #ifdef PSYCOPG_EXTENSIONS
     lobjectType.tp_alloc = PyType_GenericAlloc;

setup.py

@@ -424,6 +424,7 @@ sources = [
 
     'connection_int.c', 'connection_type.c',
     'cursor_int.c', 'cursor_type.c',
+    'diagnostics_type.c',
     'lobject_int.c', 'lobject_type.c',
     'notify_type.c', 'xid_type.c',
 
@@ -437,7 +438,7 @@ sources = [
 depends = [
     # headers
     'config.h', 'pgtypes.h', 'psycopg.h', 'python.h',
-    'connection.h', 'cursor.h', 'green.h', 'lobject.h',
+    'connection.h', 'cursor.h', 'diagnostics.h', 'green.h', 'lobject.h',
     'notify.h', 'pqpath.h', 'xid.h',
 
     'adapter_asis.h', 'adapter_binary.h', 'adapter_datetime.h',

tests/test_module.py

@@ -22,7 +22,8 @@
 # FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
 # License for more details.
 
-from testutils import unittest, skip_before_python
+from testutils import unittest, skip_before_python, skip_before_postgres
+
 from testconfig import dsn
 
 import psycopg2
@@ -154,6 +155,24 @@ class ExceptionsTestCase(unittest.TestCase):
         self.assert_(e.pgerror)
         self.assert_(e.cursor is cur)
 
+    @skip_before_postgres(9, 3)
+    def test_diagnostics(self):
+        cur = self.conn.cursor()
+        cur.execute("""
+            create temp table test_exc (
+                data int constraint chk_eq1 check (data = 1)
+            )""")
+        try:
+            cur.execute("insert into test_exc values(2)")
+        except psycopg2.Error, exc:
+            e = exc
+        self.assertEqual(e.pgcode, '23514')
+        self.assertEqual(e.diag.schema_name[:7], "pg_temp")
+        self.assertEqual(e.diag.table_name, "test_exc")
+        self.assertEqual(e.diag.column_name, None)
+        self.assertEqual(e.diag.constraint_name, "chk_eq1")
+        self.assertEqual(e.diag.datatype_name, None)
+
     @skip_before_python(2, 5)
     def test_pickle(self):
         import pickle