Display gcm device_id as hex value in Django admin

The value appears as hex in both /admin/push_notifications/gcmdevice/
and /admin/push_notifications/gcmdevice/pk/

Author: jamaalscarlett

push_notifications/admin.py

@@ -2,7 +2,7 @@
 from django.contrib.auth import get_user_model
 from django.utils.translation import ugettext_lazy as _
 from .models import APNSDevice, GCMDevice, get_expired_tokens
-
+from django.db import connection
 
 User = get_user_model()
 
@@ -57,5 +57,18 @@ def prune_devices(self, request, queryset):
 			d.save()
 
 
+class GCMDeviceAdmin(DeviceAdmin):
+	"""
+	Inherits from DeviceAdmin to handle displaying gcm device as a hex value
+	"""
+	def device_id_hex(self, obj):
+		if connection.vendor in ("mysql", "sqlite"):
+			return hex(obj.device_id).rstrip("L")
+		else:
+			return obj.device_id
+	device_id_hex.short_description = "Device ID"
+
+	list_display = ("__unicode__", "device_id_hex", "user", "active", "date_created")
+
 admin.site.register(APNSDevice, DeviceAdmin)
-admin.site.register(GCMDevice, DeviceAdmin)
+admin.site.register(GCMDevice, GCMDeviceAdmin)

push_notifications/fields.py

@@ -10,7 +10,7 @@
 __all__ = ["HexadecimalField", "HexIntegerField"]
 
 
-hex_re = re.compile(r"^[0-9A-f]+$")
+hex_re = re.compile(r"^(([0-9A-f])|(0x[0-9A-f]))+$")
 postgres_engines = [
 	"django.db.backends.postgresql_psycopg2",
 	"django.contrib.gis.db.backends.postgis",
@@ -25,6 +25,13 @@ def __init__(self, *args, **kwargs):
 		self.default_validators = [RegexValidator(hex_re, _("Enter a valid hexadecimal number"), "invalid")]
 		super(HexadecimalField, self).__init__(*args, **kwargs)
 
+	def prepare_value(self, value):
+		# converts bigint from db to hex before it is displayed in admin
+		if value and not isinstance(value, six.string_types) \
+			and connection.vendor in ("mysql", "sqlite"):
+			value = hex(value).rstrip("L")
+		return super(forms.CharField, self).prepare_value(value)
+
 
 class HexIntegerField(six.with_metaclass(models.SubfieldBase, models.BigIntegerField)):
 	"""