[AVRO-1518] Python client support decimal.Decimal types -> double encoding / decoding

• Type: Improvement
• Status: Patch Available
• Priority: Major
• Resolution: Unresolved
• Fix Version/s: 1.9.0
• Component/s: python
• Tags: python
• Assignee: Scott Reynolds
• Reporter: Scott Reynolds
• Created: 23/May/14 21:09
• Updated: 24/Oct/19 08:25

Description

Python standard library > 2.4 provides a Decimal type that has much better semantics then standard binary float. Avro library should be able to accept Decimal's and encode them as doubles.
(https://docs.python.org/2/library/decimal.html)

I also believe it should, by default, turn Avro double's into Decimal object instead of a float.

Simple patch allows for encoding a Decimal into an Avro double

--- io.py	2014-05-23 13:41:14.000000000 -0700
+++ /Users/sreynolds/Projects/avro-1.7.6 2/src/avro/io.py	2014-05-23 13:44:03.000000000 -0700
@@ -46,6 +46,11 @@ try:
 except ImportError:
 	import simplejson as json

+try:
+        from decimal import Decimal
+except ImportError:
+        Decimal = float
+
 #
 # Constants
 #
@@ -117,7 +122,7 @@ def validate(expected_schema, datum):
             and LONG_MIN_VALUE <= datum <= LONG_MAX_VALUE)
   elif schema_type in ['float', 'double']:
     return (isinstance(datum, int) or isinstance(datum, long)
-            or isinstance(datum, float))
+            or isinstance(datum, float) or instance(datum, Decimal))
   elif schema_type == 'fixed':
     return isinstance(datum, str) and len(datum) == expected_schema.size
   elif schema_type == 'enum':