Add support for additional datetime input formats

The frontend library uses an datetime strong format for it's base language (US English)
that is not supported by Python's datetime. This commit adds custom formats to
support the frontend strings.

babybuddy/formats/en/formats.py

@@ -0,0 +1,9 @@
+# -*- coding: utf-8 -*-
+from django.utils.formats import get_format
+
+# Adds support for datetime formats used by frontend.
+formats = get_format('DATETIME_INPUT_FORMATS', lang='en')
+DATETIME_INPUT_FORMATS = [
+    '%m/%d/%Y %I:%M:%S %p',
+    '%m/%d/%Y %I:%M %p'
+] + formats

babybuddy/settings/base.py

@@ -107,18 +107,19 @@ LOGIN_URL = '/login/'
 LOGOUT_REDIRECT_URL = '/login/'
 
 
-# Internationalization
-# https://docs.djangoproject.com/en/3.0/topics/i18n/
+# Timezone
+# https://docs.djangoproject.com/en/3.0/topics/i18n/timezones/
 
-LANGUAGE_CODE = 'en'
+USE_TZ = True
 
 TIME_ZONE = os.environ.get('TIME_ZONE', 'Etc/UTC')
 
+# Internationalization
+# https://docs.djangoproject.com/en/3.0/topics/i18n/
+
 USE_I18N = True
 
-USE_L10N = True
-
-USE_TZ = True
+LANGUAGE_CODE = 'en'
 
 LOCALE_PATHS = [
     os.path.join(BASE_DIR, "locale"),
@@ -134,6 +135,14 @@ LANGUAGES = [
 ]
 
 
+# Format localization
+# https://docs.djangoproject.com/en/3.0/topics/i18n/formatting/
+
+USE_L10N = True
+
+FORMAT_MODULE_PATH = ['babybuddy.formats']
+
+
 # Static files (CSS, JavaScript, Images)
 # https://docs.djangoproject.com/en/3.0/howto/static-files/
 # http://whitenoise.evans.io/en/stable/django.html

babybuddy/tests/tests_formats.py

@@ -0,0 +1,24 @@
+# -*- coding: utf-8 -*-
+import datetime
+
+from django.core.exceptions import ValidationError
+from django.forms.fields import DateTimeField
+from django.test import TestCase
+
+
+class FormatsTestCase(TestCase):
+    def test_datetime_input_formats(self):
+        field = DateTimeField()
+        supported_custom_examples = [
+            '01/20/2020 9:30 AM',
+            '01/20/2020 9:30:03 AM',
+            '10/01/2020 11:30 PM',
+            '10/01/2020 11:30:03 AM',
+        ]
+
+        for example in supported_custom_examples:
+            result = field.to_python(example)
+            self.assertIsInstance(result, datetime.datetime)
+
+        with self.assertRaises(ValidationError):
+            field.to_python('invalid date string!')