Merge pull request #54 from qweqq/patch-2

fix #53 Loss of scale when reading numeric with zero value

Author: pcisar

src/firebird/driver/core.py

@@ -3392,7 +3392,7 @@ def _extract_db_array_to_list(self, esize: int, dtype: int, subtype: int,
                 elif dtype in (a.blr_short, a.blr_long, a.blr_int64):
                     val = (0).from_bytes(buf[bufpos:bufpos + esize], 'little', signed=True)
                     if subtype or scale:
-                        val = decimal.Decimal(val) / _ten_to[abs(scale)]
+                        val = decimal.Decimal(val).scaleb(-abs(scale))
                 elif dtype == a.blr_bool:
                     val = (0).from_bytes(buf[bufpos:bufpos + esize], 'little') == 1
                 elif dtype == a.blr_float:
@@ -3799,7 +3799,7 @@ def _unpack_output(self) -> tuple:
                     value = (0).from_bytes(buffer[offset:offset + length], 'little', signed=True)
                     # It's scalled integer?
                     if desc.subtype or desc.scale:
-                        value = decimal.Decimal(value) / _ten_to[abs(desc.scale)]
+                        value = decimal.Decimal(value).scaleb(-abs(desc.scale))
                 elif datatype == SQLDataType.DATE:
                     value = _util.decode_date(buffer[offset:offset+length])
                 elif datatype == SQLDataType.TIME:

tests/test_issues.py

@@ -31,3 +31,11 @@ def test_issue_02(db_connection):
         cur.execute('select C1,C2,C3 from T2 where C1 = 1')
         rows = cur.fetchall()
         assert rows == [(1, None, 1)]
+
+def test_issue_53(db_connection):
+    with db_connection.cursor() as cur:
+        cur.execute("select cast('0.00' as numeric(9,2)) from rdb$database")
+        numeric_val = cur.fetchone()[0]
+        numeric_val_exponent = numeric_val.as_tuple()[2]
+        db_connection.commit()
+        assert numeric_val_exponent == -2