From f432bc8fe15507653caff6f57e54d4bf6a78fbd7 Mon Sep 17 00:00:00 2001
From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Sat, 3 Apr 2010 10:58:13 -0400
Subject: [PATCH] - the Numeric type raises an *enormous* warning when expected
 to convert floats to Decimal from a DBAPI that returns floats. This includes
 SQLite, Oracle, Sybase, MS-SQL. [ticket:1759]

---
 CHANGES                                     |  5 +++++
 lib/sqlalchemy/dialects/oracle/cx_oracle.py |  1 +
 lib/sqlalchemy/types.py                     | 10 +++++++++-
 test/dialect/test_oracle.py                 |  5 +++--
 test/sql/test_types.py                      |  7 ++++---
 5 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/CHANGES b/CHANGES
index a7c0ef4d48..6ad85a17c2 100644
--- a/CHANGES
+++ b/CHANGES
@@ -85,6 +85,11 @@ CHANGES
      render inside of column expressions already assigned a label.
      [ticket:1747]
 
+   - the Numeric type raises an *enormous* warning when expected
+     to convert floats to Decimal from a DBAPI that returns floats.
+     This includes SQLite, Oracle, Sybase, MS-SQL.
+     [ticket:1759]
+     
 - postgresql
    - The psycopg2 dialect will log NOTICE messages via the
      "sqlalchemy.dialects.postgresql" logger name. 
diff --git a/lib/sqlalchemy/dialects/oracle/cx_oracle.py b/lib/sqlalchemy/dialects/oracle/cx_oracle.py
index 91af6620bc..c02f188861 100644
--- a/lib/sqlalchemy/dialects/oracle/cx_oracle.py
+++ b/lib/sqlalchemy/dialects/oracle/cx_oracle.py
@@ -345,6 +345,7 @@ class ReturningResultProxy(base.FullyBufferedResultProxy):
 class OracleDialect_cx_oracle(OracleDialect):
     execution_ctx_cls = OracleExecutionContext_cx_oracle
     statement_compiler = OracleCompiler_cx_oracle
+
     driver = "cx_oracle"
     
     colspecs = colspecs = {
diff --git a/lib/sqlalchemy/types.py b/lib/sqlalchemy/types.py
index 16cd57f268..dba75b36e2 100644
--- a/lib/sqlalchemy/types.py
+++ b/lib/sqlalchemy/types.py
@@ -939,6 +939,13 @@ class Numeric(_DateAffinity, TypeEngine):
                 # we're a "numeric", DBAPI will give us Decimal directly
                 return None
             else:
+                util.warn("Dialect %s+%s does *not* support Decimal objects natively, "
+                            "and SQLAlchemy must convert from floating point - "
+                            "rounding errors and other issues may occur. "
+                            "Please consider storing Decimal numbers as strings or "
+                            "integers on this platform for lossless storage." % 
+                            (dialect.name, dialect.driver))
+                
                 # we're a "numeric", DBAPI returns floats, convert.
                 if self.scale is not None:
                     return processors.to_decimal_processor_factory(_python_Decimal, self.scale)
@@ -976,7 +983,8 @@ class Float(Numeric):
         :param precision: the numeric precision for use in DDL ``CREATE TABLE``.
         
         :param asdecimal: the same flag as that of :class:`Numeric`, but
-          defaults to ``False``.
+          defaults to ``False``.   Note that setting this flag to ``True``
+          results in floating point conversion.
 
         """
         self.precision = precision
diff --git a/test/dialect/test_oracle.py b/test/dialect/test_oracle.py
index bcb34b05c7..29014799a6 100644
--- a/test/dialect/test_oracle.py
+++ b/test/dialect/test_oracle.py
@@ -34,9 +34,9 @@ create or replace procedure foo(x_in IN number, x_out OUT number, y_out OUT numb
     def test_out_params(self):
         result = testing.db.execute(text("begin foo(:x_in, :x_out, :y_out, :z_out); end;", 
                         bindparams=[
-                                bindparam('x_in', Numeric), 
+                                bindparam('x_in', Float), 
                                 outparam('x_out', Integer), 
-                                outparam('y_out', Numeric), 
+                                outparam('y_out', Float), 
                                 outparam('z_out', String)]), 
                                 x_in=5)
         eq_(
@@ -627,6 +627,7 @@ class TypesTest(TestBase, AssertsCompiledSQL):
         finally:
             metadata.drop_all()
         
+    @testing.emits_warning(r".*does \*not\* support Decimal objects natively")    
     def test_numerics(self):
         m = MetaData(testing.db)
         t1 = Table('t1', m, 
diff --git a/test/sql/test_types.py b/test/sql/test_types.py
index 089ef727d2..764ac75848 100644
--- a/test/sql/test_types.py
+++ b/test/sql/test_types.py
@@ -1057,6 +1057,7 @@ class NumericTest(TestBase):
     def teardown(self):
         metadata.drop_all()
         
+    @testing.emits_warning(r".*does \*not\* support Decimal objects natively")    
     def _do_test(self, type_, input_, output, filter_ = None):
         t = Table('t', metadata, Column('x', type_))
         t.create()
@@ -1067,10 +1068,10 @@ class NumericTest(TestBase):
         if filter_:
             result = set(filter_(x) for x in result)
             output = set(filter_(x) for x in output)
-        print result
-        print output
+        #print result
+        #print output
         eq_(result, output)
-        
+    
     def test_numeric_as_decimal(self):
         self._do_test(
             Numeric(precision=8, scale=4),
-- 
2.47.3