CONPY-49: Added support for Decimal type

1) When retrieving data with column type MYSQL_TYPE_NEWDECIMAL C/Python
now loads the decimal module and converts data from string into Pythons
decimal.Decimal type.

2) Wnen sending a decimal.Decimal parameter, value will be converted to string
and send with type MYSQL_TYPE_NEWDECIMAL to server.

include/mariadb_python.h

@@ -273,6 +273,8 @@ extern PyObject *Mariadb_NotSupportedError;
 extern PyObject *Mariadb_Warning;
 
 extern PyObject *Mrdb_Pickle;
+extern PyObject *decimal_module,
+                *decimal_type;
 
 /* Object types */
 extern PyTypeObject MrdbPool_Type;

src/mariadb.c

@@ -26,6 +26,8 @@
 
 PyObject *Mrdb_Pickle= NULL;
 PyObject *cnx_pool= NULL;
+PyObject *decimal_module= NULL,
+         *decimal_type= NULL;
 extern uint16_t max_pool_size;
 
 int
@@ -146,6 +148,13 @@ PyMODINIT_FUNC PyInit_mariadb(void)
         goto error;
     }
 
+    /* Import Decimal support (CONPY-49) */
+    if (!(decimal_module= PyImport_ImportModule("decimal")) ||
+        !(decimal_type= PyObject_GetAttrString(decimal_module, "Decimal")))
+    {
+        goto error;
+    }
+
     /* we need pickle for object serialization */
     Mrdb_Pickle= PyImport_ImportModule("pickle");
 

src/mariadb_codecs.c

@@ -413,12 +413,19 @@ field_fetch_fromtext(MrdbCursor *self, char *data, unsigned int column)
                                                 (Py_ssize_t)length[column]);
             }
             break;
+        case MYSQL_TYPE_NEWDECIMAL:
+        {
+            PyObject *decimal;
+
+            decimal= PyObject_CallFunction(decimal_type, "s", (const char *)data);
+            self->values[column]= decimal;
+            break;
+        }
         case MYSQL_TYPE_STRING:
         case MYSQL_TYPE_VAR_STRING:
         case MYSQL_TYPE_JSON:
         case MYSQL_TYPE_VARCHAR:
         case MYSQL_TYPE_DECIMAL:
-        case MYSQL_TYPE_NEWDECIMAL:
         case MYSQL_TYPE_SET:
         case MYSQL_TYPE_ENUM:
         {
@@ -703,12 +710,17 @@ mariadb_get_column_info(PyObject *obj, MrdbParamInfo *paraminfo)
     } else if (PyDateTime_CheckExact(obj)) {
         paraminfo->type= MYSQL_TYPE_DATETIME;
         return 0;
-    } else if (Py_TYPE(obj) == &PyUnicode_Type) {
+   } else if (Py_TYPE(obj) == &PyUnicode_Type) {
         paraminfo->type= MYSQL_TYPE_VAR_STRING;
         return 0;
     } else if (obj == Py_None) {
         paraminfo->type= MYSQL_TYPE_NULL;
         return 0;
+    } else if (!strcmp(Py_TYPE(obj)->tp_name, "decimal.Decimal")) {
+        /* CINPY-49: C-API has no correspondent data type for DECUMAL column type,
+           so we need to convert decimal.Decimal Object to string during callback */
+        paraminfo->type= MYSQL_TYPE_NEWDECIMAL;
+        return 0;
     }
     else {
         /* no corresponding object, return error  */
@@ -868,7 +880,7 @@ mariadb_get_parameter_info(MrdbCursor *self,
             if (rc == 2)
             {
                 mariadb_throw_exception(NULL, Mariadb_DataError, 0,
-                    "Data type '%s' in column %d not supported in MariaDB",
+                    "Data type '%s' in column %d not supported in MariaDB Connector/Python",
                      Py_TYPE(paramvalue.value)->tp_name, column_nr);
             }
        
@@ -1174,9 +1186,19 @@ mariadb_param_to_bind(MYSQL_BIND *bind,
             bind->buffer= &value->tm;
             mariadb_pydate_to_tm(bind->buffer_type, value->value, &value->tm);
             break;
+        case MYSQL_TYPE_NEWDECIMAL:
+            {
+                Py_ssize_t len;
+                PyObject *obj= PyObject_Str(value->value);
+                bind->buffer= (void *)PyUnicode_AsUTF8AndSize(obj, &len);
+                bind->buffer_length= (unsigned long)len;
+                Py_DECREF(obj);
+            }
+            break;
         case MYSQL_TYPE_VAR_STRING:
             {
                 Py_ssize_t len;
+
                 bind->buffer= (void *)PyUnicode_AsUTF8AndSize(value->value, &len);
                 bind->buffer_length= (unsigned long)len;
                 break;

src/mariadb_cursor.c

@@ -726,6 +726,7 @@ PyObject *MrdbCursor_execute(MrdbCursor *self,
 
                         /* we need to clear the result first, otherwise the cursor remains
                            in usuable state (query out of order) */
+
                         if ((result= mysql_store_result(self->stmt->mysql)))
                             mysql_free_result(result);
 

test/integration/test_cursor.py

@@ -5,6 +5,7 @@ import collections
 import datetime
 import unittest
 import os
+from decimal import Decimal
 
 import mariadb
 
@@ -786,7 +787,7 @@ class TestCursor(unittest.TestCase):
         self.assertEqual(row[0], 0)
         del con
 
-    def test_conpy49(self):
+    def test_conpy48(self):
         con= create_connection()
         cur=con.cursor()
         cur.execute("select %s", [True])
@@ -834,6 +835,15 @@ class TestCursor(unittest.TestCase):
         cur.execute("drop table if exists temp")
         del con
 
+    def test_conpy49(self):
+        con= create_connection()
+        cur=con.cursor()
+        cur.execute("create temporary table t1 (a decimal(10,2))")
+        cur.execute("insert into t1 values (?)", (Decimal('10.2'),))
+        cur.execute("select a from t1")
+        row=cur.fetchone()
+        self.assertEqual(row[0], Decimal('10.20'))
+        del con
 
 if __name__ == '__main__':
     unittest.main()