Fix #11 -- Add custom measurement class support (#76)

Author: webit-mdowney

django_measurement/models.py

@@ -1,4 +1,5 @@
 import logging
+import warnings
 
 from django.db.models import FloatField
 from django.utils.translation import ugettext_lazy as _
@@ -29,6 +30,10 @@ def __init__(self, verbose_name=None, name=None, measurement=None,
                  measurement_class=None, unit_choices=None, *args, **kwargs):
 
         if not measurement and measurement_class is not None:
+            warnings.warn(
+                "\"measurement_class\" will be removed in version 4.0",
+                DeprecationWarning
+            )
             measurement = getattr(measures, measurement_class)
 
         if not measurement:
@@ -42,7 +47,6 @@ def __init__(self, verbose_name=None, name=None, measurement=None,
             )
 
         self.measurement = measurement
-        self.measurement_class = str(measurement.__name__)
         self.widget_args = {
             'measurement': measurement,
             'unit_choices': unit_choices,
@@ -53,7 +57,7 @@ def __init__(self, verbose_name=None, name=None, measurement=None,
 
     def deconstruct(self):
         name, path, args, kwargs = super(MeasurementField, self).deconstruct()
-        kwargs['measurement_class'] = self.measurement_class
+        kwargs['measurement'] = self.measurement
         return name, path, args, kwargs
 
     def get_prep_value(self, value):
@@ -97,7 +101,7 @@ def to_python(self, value):
 
         msg = "You assigned a %s instead of %s to %s.%s.%s, unit was guessed to be \"%s\"." % (
             type(value).__name__,
-            self.measurement_class,
+            str(self.measurement.__name__),
             self.model.__module__,
             self.model.__name__,
             self.name,

tests/models.py

@@ -3,6 +3,7 @@
 from measurement import measures
 
 from django_measurement.models import MeasurementField
+from tests.custom_measure_base import DegreePerTime, Temperature, Time
 
 
 class MeasurementTestModel(models.Model):
@@ -51,6 +52,15 @@ class MeasurementTestModel(models.Model):
         blank=True, null=True,
     )
 
+    measurement_temperature2 = MeasurementField(
+        measurement_class='Temperature',
+        validators=[
+            MinValueValidator(measures.Temperature(1.0)),
+            MaxValueValidator(measures.Temperature(3.0))
+        ],
+        blank=True, null=True,
+    )
+
     measurement_speed_mph = MeasurementField(
         measurement=measures.Speed,
         unit_choices=(('mi__hr', 'mph'),),
@@ -61,5 +71,20 @@ class MeasurementTestModel(models.Model):
         blank=True, null=True,
     )
 
+    measurement_custom_degree_per_time = MeasurementField(
+        measurement=DegreePerTime,
+        blank=True, null=True,
+    )
+
+    measurement_custom_temperature = MeasurementField(
+        measurement=Temperature,
+        blank=True, null=True,
+    )
+
+    measurement_custom_time = MeasurementField(
+        measurement=Time,
+        blank=True, null=True,
+    )
+
     def __str__(self):
         return self.measurement

tests/test_fields.py

@@ -1,10 +1,12 @@
+# -*- coding: utf-8 -*-
 import pytest
 from django.core.exceptions import ValidationError
 from django.utils import module_loading
 from measurement import measures
 from measurement.measures import Distance
 
 from django_measurement.forms import MeasurementField
+from tests.custom_measure_base import DegreePerTime, Temperature, Time
 from tests.forms import (
     BiDimensionalLabelTestForm, LabelTestForm, MeasurementTestForm, SITestForm
 )
@@ -133,6 +135,9 @@ def test_storage_and_retrieval_of_measurement_choice(self):
     ('measurement_speed', measures.Speed),
     ('measurement_temperature', measures.Temperature),
     ('measurement_speed_mph', measures.Speed),
+    ('measurement_custom_degree_per_time', DegreePerTime),
+    ('measurement_custom_temperature', Temperature),
+    ('measurement_custom_time', Time),
 ])
 class TestDeconstruct:
     def test_deconstruct(self, fieldname, measure_cls):
@@ -145,8 +150,11 @@ def test_deconstruct(self, fieldname, measure_cls):
         assert args == []
         assert kwargs['blank'] == field.blank
         assert kwargs['null'] == field.null
-        assert kwargs['measurement_class'] == measure_cls.__name__
-        assert kwargs['measurement_class'] == field.measurement_class
+        if 'measurement_class' in kwargs:
+            assert kwargs['measurement_class'] == measure_cls.__name__
+            assert kwargs['measurement_class'] == field.measurement_class
+        else:
+            assert 'measurement' in kwargs
 
         new_cls = module_loading.import_string(path)
         new_field = new_cls(name=name, *args, **kwargs)