- pg8000 + postgresql dialects now check for float/numeric return

types to more intelligently determine float() vs. Decimal(),
[ticket:1567]
- since result processing is a hot issue of late, the DBAPI type
returned from cursor.description is certainly useful in cases like
these to determine an efficient result processor.   There's likely
other result processors that can make use of it.  But, backwards
incompat change to result_processor().  Happy major version number..

1 files changed, 35 insertions, 14 deletions

diff --git a/lib/sqlalchemy/dialects/postgresql/pg8000.py b/lib/sqlalchemy/dialects/postgresql/pg8000.py
index 17fe86be6..e90bebb6b 100644
--- a/lib/sqlalchemy/dialects/postgresql/pg8000.py
+++ b/lib/sqlalchemy/dialects/postgresql/pg8000.py
@@ -21,25 +21,47 @@ Passing data from/to the Interval type is not supported as of yet.
 """
 from sqlalchemy.engine import default
 import decimal
-from sqlalchemy import util
+from sqlalchemy import util, exc
 from sqlalchemy import types as sqltypes
-from sqlalchemy.dialects.postgresql.base import PGDialect, PGCompiler, PGIdentifierPreparer, PGExecutionContext
+from sqlalchemy.dialects.postgresql.base import PGDialect, \
+                PGCompiler, PGIdentifierPreparer, PGExecutionContext
 
 class _PGNumeric(sqltypes.Numeric):
     def bind_processor(self, dialect):
-        return None
-
-    def result_processor(self, dialect):
+        def process(value):
+            if value is not None:
+                return float(value)
+            else:
+                return value
+        return process
+    
+    def result_processor(self, dialect, coltype):
         if self.asdecimal:
-            return None
+            if coltype in (700, 701):
+                def process(value):
+                    if value is not None:
+                        return decimal.Decimal(str(value))
+                    else:
+                        return value
+                return process
+            elif coltype == 1700:
+                # pg8000 returns Decimal natively for 1700
+                return None
+            else:
+                raise exc.InvalidRequestError("Unknown PG numeric type: %d" % coltype)
         else:
-            def process(value):
-                if isinstance(value, decimal.Decimal):
-                    return float(value)
-                else:
-                    return value
-            return process
-
+            if coltype in (700, 701):
+                # pg8000 returns float natively for 701
+                return None
+            elif coltype == 1700:
+                def process(value):
+                    if value is not None:
+                        return float(value)
+                    else:
+                        return value
+                return process
+            else:
+                raise exc.InvalidRequestError("Unknown PG numeric type: %d" % coltype)
 
 class PostgreSQL_pg8000ExecutionContext(PGExecutionContext):
     pass
@@ -79,7 +101,6 @@ class PostgreSQL_pg8000(PGDialect):
         PGDialect.colspecs,
         {
             sqltypes.Numeric : _PGNumeric,
-            sqltypes.Float: sqltypes.Float,  # prevents _PGNumeric from being used
         }
     )