Merge pull request #1 from yourlabs/decimal_normalization

Decimal normalization

Author: jpic

README.rst

@@ -47,6 +47,9 @@ django.core.serializers.python.Serializer.get_dump_object() - returns a dict,
 this app registers a slightly modified version of the default json serializer
 which returns OrderedDicts instead.
 
+In addition, dbdiff serialization forces Decimal normalization, because
+trailing zeros could happen in inconsistent ways.
+
 Cross-database fixture compatibility
 ====================================
 

dbdiff/dbdiff.py

@@ -26,8 +26,11 @@ def diff(fixture):
     try:
         out = diff.get_diff()
     except:
-        DEBUG or diff.clean()
+        if not DEBUG:
+            diff.clean()
         raise
 
-    DEBUG or diff.clean()
+    if not DEBUG:
+        diff.clean()
+
     return out

dbdiff/exceptions.py

@@ -0,0 +1,13 @@
+"""Exceptions for dbdiff module."""
+
+
+class DbDiffException(Exception):
+    """Base exception for this app."""
+
+
+class EmptyFixtures(DbDiffException):
+    """Raised when a fixtures file is empty."""
+
+    def __init__(self, path):
+        """Exception for when path does not contain any fixture data."""
+        super(EmptyFixtures, self).__init__('%s is empty' % path)

dbdiff/fixture_diff.py

@@ -10,6 +10,8 @@
 
 import ijson
 
+from .exceptions import EmptyFixtures
+
 
 class FixtureDiff(object):
     """
@@ -51,9 +53,12 @@ def fixture_indent(self):
         with open(self.fixture_path, 'r') as f:
             line = f.readline()
 
-            while ':' not in line:
+            while line and ':' not in line:
                 line = f.readline()
 
+            if not line:
+                raise EmptyFixtures(self.fixture_path)
+
             return len(line) - len(line.lstrip(' '))
 
     def get_diff(self):
@@ -68,7 +73,7 @@ def get_diff(self):
         cmd = 'diff -u1 %s %s | sed "1,2 d"' % (
             self.fixture_path, self.dump_path)
 
-        if apps.get_app_config('dbdiff').debug:
+        if apps.get_app_config('dbdiff').debug:  # pragma: no cover
             print(cmd)
 
         proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, shell=True)

dbdiff/fixtures/empty.json

@@ -0,0 +1,2 @@
+[
+]

dbdiff/serializers/base.py

@@ -2,6 +2,7 @@
 
 import collections
 import datetime
+import decimal
 
 
 class BaseSerializerMixin(object):
@@ -35,9 +36,19 @@ def remove_microseconds(cls, data):
                 tzinfo=value.tzinfo
             )
 
+    @classmethod
+    def normalize_decimals(cls, data):
+        """Strip trailing zeros for constitency."""
+        for key, value in data['fields'].items():
+            if not isinstance(value, decimal.Decimal):
+                continue
+
+            data['fields'][key] = value.normalize()
+
     def get_dump_object(self, obj):
         """Actual method used by Django serializers to dump dicts."""
         data = super(BaseSerializerMixin, self).get_dump_object(obj)
         self.remove_microseconds(data)
+        self.normalize_decimals(data)
         data = self.recursive_dict_sort(data)
         return data

dbdiff/tests/project/decimal_test/__init__.py

@@ -0,0 +1 @@
+"""App to test DecimalField dump predictibility."""

dbdiff/tests/project/decimal_test/fixtures/decimal_test_changed.json

@@ -0,0 +1,16 @@
+[
+{
+    "fields": {
+        "test_field": "3.1"
+    },
+    "model": "decimal_test.testmodel",
+    "pk": 1
+},
+{
+    "fields": {
+        "test_field": "1.1"
+    },
+    "model": "decimal_test.testmodel",
+    "pk": 2
+}
+]

dbdiff/tests/project/decimal_test/fixtures/decimal_test_expected.json

@@ -0,0 +1,16 @@
+[
+{
+    "fields": {
+        "test_field": "1.1"
+    },
+    "model": "decimal_test.testmodel",
+    "pk": 1
+},
+{
+    "fields": {
+        "test_field": "1.1"
+    },
+    "model": "decimal_test.testmodel",
+    "pk": 2
+}
+]

dbdiff/tests/project/decimal_test/fixtures/decimal_test_fixture.json

@@ -0,0 +1,16 @@
+[
+{
+    "fields": {
+        "test_field": "1.1"
+    },
+    "model": "decimal_test.testmodel",
+    "pk": 1
+},
+{
+    "fields": {
+        "test_field": "1.10"
+    },
+    "model": "decimal_test.testmodel",
+    "pk": 2
+}
+]