DecimalField now stores as float not string (#289)

docs/apireference.rst

@@ -54,33 +54,33 @@ Querying
 Fields
 ======
 
-.. autoclass:: mongoengine.StringField
-.. autoclass:: mongoengine.URLField
-.. autoclass:: mongoengine.EmailField
-.. autoclass:: mongoengine.IntField
-.. autoclass:: mongoengine.LongField
-.. autoclass:: mongoengine.FloatField
-.. autoclass:: mongoengine.DecimalField
-.. autoclass:: mongoengine.BooleanField
-.. autoclass:: mongoengine.DateTimeField
-.. autoclass:: mongoengine.ComplexDateTimeField
-.. autoclass:: mongoengine.EmbeddedDocumentField
-.. autoclass:: mongoengine.GenericEmbeddedDocumentField
-.. autoclass:: mongoengine.DynamicField
-.. autoclass:: mongoengine.ListField
-.. autoclass:: mongoengine.SortedListField
-.. autoclass:: mongoengine.DictField
-.. autoclass:: mongoengine.MapField
-.. autoclass:: mongoengine.ReferenceField
-.. autoclass:: mongoengine.GenericReferenceField
-.. autoclass:: mongoengine.BinaryField
-.. autoclass:: mongoengine.FileField
-.. autoclass:: mongoengine.ImageField
-.. autoclass:: mongoengine.GeoPointField
-.. autoclass:: mongoengine.SequenceField
-.. autoclass:: mongoengine.ObjectIdField
-.. autoclass:: mongoengine.UUIDField
-.. autoclass:: mongoengine.GridFSError
-.. autoclass:: mongoengine.GridFSProxy
-.. autoclass:: mongoengine.ImageGridFsProxy
-.. autoclass:: mongoengine.ImproperlyConfigured
+.. autoclass:: mongoengine.fields.StringField
+.. autoclass:: mongoengine.fields.URLField
+.. autoclass:: mongoengine.fields.EmailField
+.. autoclass:: mongoengine.fields.IntField
+.. autoclass:: mongoengine.fields.LongField
+.. autoclass:: mongoengine.fields.FloatField
+.. autoclass:: mongoengine.fields.DecimalField
+.. autoclass:: mongoengine.fields.BooleanField
+.. autoclass:: mongoengine.fields.DateTimeField
+.. autoclass:: mongoengine.fields.ComplexDateTimeField
+.. autoclass:: mongoengine.fields.EmbeddedDocumentField
+.. autoclass:: mongoengine.fields.GenericEmbeddedDocumentField
+.. autoclass:: mongoengine.fields.DynamicField
+.. autoclass:: mongoengine.fields.ListField
+.. autoclass:: mongoengine.fields.SortedListField
+.. autoclass:: mongoengine.fields.DictField
+.. autoclass:: mongoengine.fields.MapField
+.. autoclass:: mongoengine.fields.ReferenceField
+.. autoclass:: mongoengine.fields.GenericReferenceField
+.. autoclass:: mongoengine.fields.BinaryField
+.. autoclass:: mongoengine.fields.FileField
+.. autoclass:: mongoengine.fields.ImageField
+.. autoclass:: mongoengine.fields.GeoPointField
+.. autoclass:: mongoengine.fields.SequenceField
+.. autoclass:: mongoengine.fields.ObjectIdField
+.. autoclass:: mongoengine.fields.UUIDField
+.. autoclass:: mongoengine.fields.GridFSError
+.. autoclass:: mongoengine.fields.GridFSProxy
+.. autoclass:: mongoengine.fields.ImageGridFsProxy
+.. autoclass:: mongoengine.fields.ImproperlyConfigured

docs/changelog.rst

@@ -4,6 +4,7 @@ Changelog
 
 Changes in 0.8.X
 ================
+- DecimalField now stores as float not string (#289)
 - UUIDField now stores as a binary by default (#292)
 - Added Custom User Model for Django 1.5 (#285)
 - Cascading saves now default to off (#291)

docs/conf.py

@@ -173,8 +173,8 @@ latex_paper_size = 'a4'
 # Grouping the document tree into LaTeX files. List of tuples
 # (source start file, target name, title, author, documentclass [howto/manual]).
 latex_documents = [
-  ('index', 'MongoEngine.tex', u'MongoEngine Documentation',
-   u'Harry Marr', 'manual'),
+  ('index', 'MongoEngine.tex', 'MongoEngine Documentation',
+   'Ross Lawley', 'manual'),
 ]
 
 # The name of an image file (relative to this directory) to place at the top of
@@ -193,3 +193,6 @@ latex_documents = [
 
 # If false, no module index is generated.
 #latex_use_modindex = True
+
+autoclass_content = 'both'
+

docs/upgrade.rst

@@ -145,6 +145,35 @@ eg::
         a._mark_as_dirty('uuid')
         a.save()
 
+DecimalField
+------------
+
+DecimalField now store floats - previous it was storing strings and that
+made it impossible to do comparisons when querying correctly.::
+
+    # Old code
+    class Person(Document):
+        balance = DecimalField()
+
+    # New code
+    class Person(Document):
+        balance = DecimalField(force_string=True)
+
+To migrate all the uuid's you need to touch each object and mark it as dirty
+eg::
+
+    # Doc definition
+    class Person(Document):
+        balance = DecimalField()
+
+    # Mark all ReferenceFields as dirty and save
+    for p in Person.objects:
+        p._mark_as_dirty('balance')
+        p.save()
+
+.. note:: DecimalField's have also been improved with the addition of precision
+    and rounding.  See :class:`~mongoengine.DecimalField` for more information.
+
 Cascading Saves
 ---------------
 To improve performance document saves will no longer automatically cascade.

mongoengine/fields.py

@@ -260,30 +260,57 @@ class FloatField(BaseField):
 class DecimalField(BaseField):
     """A fixed-point decimal number field.
 
+    .. versionchanged:: 0.8
     .. versionadded:: 0.3
     """
 
-    def __init__(self, min_value=None, max_value=None, **kwargs):
-        self.min_value, self.max_value = min_value, max_value
+    def __init__(self, min_value=None, max_value=None, force_string=False,
+                 precision=2, rounding=decimal.ROUND_HALF_UP, **kwargs):
+        """
+        :param min_value: Validation rule for the minimum acceptable value.
+        :param max_value: Validation rule for the maximum acceptable value.
+        :param force_string: Store as a string.
+        :param precision: Number of decimal places to store.
+        :param rounding: The rounding rule from the python decimal libary:
+
+            - decimial.ROUND_CEILING (towards Infinity)
+            - decimial.ROUND_DOWN (towards zero)
+            - decimial.ROUND_FLOOR (towards -Infinity)
+            - decimial.ROUND_HALF_DOWN (to nearest with ties going towards zero)
+            - decimial.ROUND_HALF_EVEN (to nearest with ties going to nearest even integer)
+            - decimial.ROUND_HALF_UP (to nearest with ties going away from zero)
+            - decimial.ROUND_UP (away from zero)
+            - decimial.ROUND_05UP (away from zero if last digit after rounding towards zero would have been 0 or 5; otherwise towards zero)
+
+            Defaults to: ``decimal.ROUND_HALF_UP``
+
+        """
+        self.min_value = min_value
+        self.max_value = max_value
+        self.force_string = force_string
+        self.precision = decimal.Decimal(".%s" % ("0" * precision))
+        self.rounding = rounding
+
         super(DecimalField, self).__init__(**kwargs)
 
     def to_python(self, value):
-        original_value = value
-        if not isinstance(value, basestring):
-            value = unicode(value)
-        try:
-            value = decimal.Decimal(value)
-        except ValueError:
-            return original_value
+        if value is None:
             return value
 
+        return decimal.Decimal(value).quantize(self.precision,
+                                               rounding=self.rounding)
+
     def to_mongo(self, value):
+        if value is None:
+            return value
+        if self.force_string:
             return unicode(value)
+        return float(self.to_python(value))
 
     def validate(self, value):
         if not isinstance(value, decimal.Decimal):
             if not isinstance(value, basestring):
-                value = str(value)
+                value = unicode(value)
             try:
                 value = decimal.Decimal(value)
             except Exception, exc:
@@ -295,6 +322,9 @@ class DecimalField(BaseField):
         if self.max_value is not None and value > self.max_value:
             self.error('Decimal value is too large')
 
+    def prepare_query_value(self, op, value):
+        return self.to_mongo(value)
+
 
 class BooleanField(BaseField):
     """A boolean field type.

mongoengine/queryset/transform.py

@@ -144,7 +144,7 @@ def query(_doc_cls=None, _field_operation=False, **query):
         merge_query[k].append(mongo_query[k])
         del mongo_query[k]
         if isinstance(v, list):
-            value = [{k:val} for val in v]
+            value = [{k: val} for val in v]
             if '$and' in mongo_query.keys():
                 mongo_query['$and'].append(value)
             else:

tests/fields/fields.py

@@ -272,10 +272,8 @@ class FieldTest(unittest.TestCase):
 
         Person.drop_collection()
 
-        person = Person()
-        person.height = Decimal('1.89')
-        person.save()
-        person.reload()
+        Person(height=Decimal('1.89')).save()
+        person = Person.objects.first()
         self.assertEqual(person.height, Decimal('1.89'))
 
         person.height = '2.0'
@@ -289,6 +287,45 @@ class FieldTest(unittest.TestCase):
 
         Person.drop_collection()
 
+    def test_decimal_comparison(self):
+
+        class Person(Document):
+            money = DecimalField()
+
+        Person.drop_collection()
+
+        Person(money=6).save()
+        Person(money=8).save()
+        Person(money=10).save()
+
+        self.assertEqual(2, Person.objects(money__gt=Decimal("7")).count())
+        self.assertEqual(2, Person.objects(money__gt=7).count())
+        self.assertEqual(2, Person.objects(money__gt="7").count())
+
+    def test_decimal_storage(self):
+        class Person(Document):
+            btc = DecimalField(precision=4)
+
+        Person.drop_collection()
+        Person(btc=10).save()
+        Person(btc=10.1).save()
+        Person(btc=10.11).save()
+        Person(btc="10.111").save()
+        Person(btc=Decimal("10.1111")).save()
+        Person(btc=Decimal("10.11111")).save()
+
+        # How its stored
+        expected = [{'btc': 10.0}, {'btc': 10.1}, {'btc': 10.11},
+                    {'btc': 10.111}, {'btc': 10.1111}, {'btc': 10.1111}]
+        actual = list(Person.objects.exclude('id').as_pymongo())
+        self.assertEqual(expected, actual)
+
+        # How it comes out locally
+        expected = [Decimal('10.0000'), Decimal('10.1000'), Decimal('10.1100'),
+                    Decimal('10.1110'), Decimal('10.1111'), Decimal('10.1111')]
+        actual = list(Person.objects().scalar('btc'))
+        self.assertEqual(expected, actual)
+
     def test_boolean_validation(self):
         """Ensure that invalid values cannot be assigned to boolean fields.
         """

tests/migration/__init__.py

@@ -1,4 +1,5 @@
 from convert_to_new_inheritance_model import *
+from decimalfield_as_float import *
 from refrencefield_dbref_to_object_id import *
 from turn_off_inheritance import *
 from uuidfield_to_binary import *

tests/migration/decimalfield_as_float.py

@@ -0,0 +1,50 @@
+ # -*- coding: utf-8 -*-
+import unittest
+import decimal
+from decimal import Decimal
+
+from mongoengine import Document, connect
+from mongoengine.connection import get_db
+from mongoengine.fields import StringField, DecimalField, ListField
+
+__all__ = ('ConvertDecimalField', )
+
+
+class ConvertDecimalField(unittest.TestCase):
+
+    def setUp(self):
+        connect(db='mongoenginetest')
+        self.db = get_db()
+
+    def test_how_to_convert_decimal_fields(self):
+        """Demonstrates migrating from 0.7 to 0.8
+        """
+
+        # 1. Old definition - using dbrefs
+        class Person(Document):
+            name = StringField()
+            money = DecimalField(force_string=True)
+            monies = ListField(DecimalField(force_string=True))
+
+        Person.drop_collection()
+        Person(name="Wilson Jr", money=Decimal("2.50"),
+               monies=[Decimal("2.10"), Decimal("5.00")]).save()
+
+        # 2. Start the migration by changing the schema
+        # Change DecimalField - add precision and rounding settings
+        class Person(Document):
+            name = StringField()
+            money = DecimalField(precision=2, rounding=decimal.ROUND_HALF_UP)
+            monies = ListField(DecimalField(precision=2,
+                                            rounding=decimal.ROUND_HALF_UP))
+
+        # 3. Loop all the objects and mark parent as changed
+        for p in Person.objects:
+            p._mark_as_changed('money')
+            p._mark_as_changed('monies')
+            p.save()
+
+        # 4. Confirmation of the fix!
+        wilson = Person.objects(name="Wilson Jr").as_pymongo()[0]
+        self.assertTrue(isinstance(wilson['money'], float))
+        self.assertTrue(all([isinstance(m, float) for m in wilson['monies']]))

tests/queryset/queryset.py

@@ -3262,9 +3262,9 @@ class QuerySetTest(unittest.TestCase):
         self.assertTrue(isinstance(results[0], dict))
         self.assertTrue(isinstance(results[1], dict))
         self.assertEqual(results[0]['name'], 'Bob Dole')
-        self.assertEqual(results[0]['price'], '1.11')
+        self.assertEqual(results[0]['price'], 1.11)
         self.assertEqual(results[1]['name'], 'Barack Obama')
-        self.assertEqual(results[1]['price'], '2.22')
+        self.assertEqual(results[1]['price'], 2.22)
 
         # Test coerce_types
         users = User.objects.only('name', 'price').as_pymongo(coerce_types=True)