Add support for custom decimal string formatter (#125)

* Handle possible input types to format as decimals

* Stringify resulting data post-decimal conversion, fix return

* Pylint fixes

* added tests for singer.decimal logic

* modified transform to parse NaN values as NaNs

* changed logic to transform occurrence of snan into a nan

Co-authored-by: Jacob Baca <jbaca@stitchdata.com>
Co-authored-by: Jacob Baca <52418765+jacobrobertbaca@users.noreply.github.com>

Author: 3 people

singer/transform.py

@@ -1,4 +1,5 @@
 import datetime
+import decimal
 import logging
 import re
 from jsonschema import RefResolver
@@ -271,7 +272,25 @@ def _transform(self, data, typ, schema, path):
                 return False, None
 
             return True, data
+        elif schema.get("format") == "singer.decimal":
+            if data is None:
+                return False, None
+
+            if isinstance(data, (str, float, int)):
+                try:
+                    return True, str(decimal.Decimal(str(data)).normalize())
+                except:
+                    return False, None
+            elif isinstance(data, decimal.Decimal):
+                try:
+                    if data.is_snan():
+                        return True, 'NaN'
+                    else:
+                        return True, str(data.normalize())
+                except:
+                    return False, None
 
+            return False, None
         elif typ == "object":
             # Objects do not necessarily specify properties
             return self._transform_object(data,

tests/test_transform.py

@@ -1,4 +1,5 @@
 import unittest
+import decimal
 from singer import transform
 from singer.transform import *
 
@@ -252,6 +253,68 @@ def test_null_object_transform(self):
         empty_data = {'addrs': {}}
         self.assertDictEqual(empty_data, transform(empty_data, schema))
 
+    def test_decimal_types_transform(self):
+        schema =  {"type": "object",
+                   "properties": {"percentage": {"type": ["string"],
+                                                 "format": "singer.decimal"}}}
+
+        inf = {'percentage': 'Infinity'}
+        negative_inf = {'percentage': '-Infinity'}
+        root2  = {'percentage': 1.4142135623730951}
+        nan = {'percentage': decimal.Decimal('NaN')}
+        snan = {'percentage': decimal.Decimal('sNaN')}
+
+        self.assertEquals(inf, transform(inf, schema))
+        self.assertEquals(negative_inf, transform(negative_inf, schema))
+        self.assertEquals({'percentage': '1.4142135623730951'}, transform(root2, schema))
+        self.assertEquals({'percentage': 'NaN'}, transform(nan, schema))
+        self.assertEquals({'percentage': 'NaN'}, transform(snan, schema))
+
+
+        str1 = {'percentage':'0.1'}
+        str2 = {'percentage': '0.0000000000001'}
+        str3 = {'percentage': '1E+13'}
+        str4 = {'percentage': '100'}
+        str5 = {'percentage': '-100'}
+        self.assertEquals(str1, transform(str1, schema))
+        self.assertEquals({'percentage': '1E-13'}, transform(str2, schema))
+        self.assertEquals({'percentage': '1E+13'}, transform(str3, schema))
+        self.assertEquals({'percentage': '1E+2'}, transform(str4, schema))
+        self.assertEquals({'percentage': '-1E+2'}, transform(str5, schema))
+
+        float1 = {'percentage': 12.0000000000000000000000000001234556}
+        float2 = {'percentage': 0.0123}
+        float3 = {'percentage': 100.0123}
+        float4 = {'percentage': -100.0123}
+        self.assertEquals({'percentage':'12'}, transform(float1, schema))
+        self.assertEquals({'percentage':'0.0123'}, transform(float2, schema))
+        self.assertEquals({'percentage':'100.0123'}, transform(float3, schema))
+        self.assertEquals({'percentage':'-100.0123'}, transform(float4, schema))
+
+        int1 = {'percentage': 123}
+        int2 = {'percentage': 0}
+        int3 = {'percentage': -1000}
+        self.assertEquals({'percentage':'123'}, transform(int1, schema))
+        self.assertEquals({'percentage':'0'}, transform(int2, schema))
+        self.assertEquals({'percentage':'-1E+3'}, transform(int3, schema))
+
+        dec1 = {'percentage': decimal.Decimal('1.1010101')}
+        dec2 = {'percentage': decimal.Decimal('.111111111111111111111111')}
+        dec3 = {'percentage': decimal.Decimal('-.111111111111111111111111')}
+        dec4 = {'percentage': decimal.Decimal('100')}
+        self.assertEquals({'percentage':'1.1010101'}, transform(dec1, schema))
+        self.assertEquals({'percentage':'0.111111111111111111111111'}, transform(dec2, schema))
+        self.assertEquals({'percentage':'-0.111111111111111111111111'}, transform(dec3, schema))
+        self.assertEquals({'percentage':'1E+2'}, transform(dec4, schema))
+
+        bad1 = {'percentage': 'fsdkjl'}
+        with self.assertRaises(SchemaMismatch):
+            transform(bad1, schema)
+
+        badnull = {'percentage': None}
+        with self.assertRaises(SchemaMismatch):
+            self.assertEquals({'percentage':None}, transform(badnull, schema))
+
 class TestTransformsWithMetadata(unittest.TestCase):
 
     def test_drops_no_data_when_not_dict(self):