"""
Useful form fields for use with the Django ORM.
"""
from __future__ import unicode_literals
import datetime
import operator
try:
from django.conf import settings
from django.utils import timezone
has_timezone = True
except ImportError:
has_timezone = False
from wtforms import fields, widgets
from wtforms.compat import string_types
from wtforms.validators import ValidationError
__all__ = (
'ModelSelectField', 'QuerySetSelectField', 'DateTimeField'
)
[docs]class QuerySetSelectField(fields.SelectFieldBase):
"""
Given a QuerySet either at initialization or inside a view, will display a
select drop-down field of choices. The `data` property actually will
store/keep an ORM model instance, not the ID. Submitting a choice which is
not in the queryset will result in a validation error.
Specify `get_label` to customize the label associated with each option. If
a string, this is the name of an attribute on the model object to use as
the label text. If a one-argument callable, this callable will be passed
model instance and expected to return the label text. Otherwise, the model
object's `__str__` or `__unicode__` will be used.
If `allow_blank` is set to `True`, then a blank choice will be added to the
top of the list. Selecting this choice will result in the `data` property
being `None`. The label for the blank choice can be set by specifying the
`blank_text` parameter.
"""
widget = widgets.Select()
def __init__(self, label=None, validators=None, queryset=None, get_label=None, allow_blank=False, blank_text='', **kwargs):
super(QuerySetSelectField, self).__init__(label, validators, **kwargs)
self.allow_blank = allow_blank
self.blank_text = blank_text
self._set_data(None)
if queryset is not None:
self.queryset = queryset.all() # Make sure the queryset is fresh
if get_label is None:
self.get_label = lambda x: x
elif isinstance(get_label, string_types):
self.get_label = operator.attrgetter(get_label)
else:
self.get_label = get_label
def _get_data(self):
if self._formdata is not None:
for obj in self.queryset:
if obj.pk == self._formdata:
self._set_data(obj)
break
return self._data
def _set_data(self, data):
self._data = data
self._formdata = None
data = property(_get_data, _set_data)
def iter_choices(self):
if self.allow_blank:
yield ('__None', self.blank_text, self.data is None)
for obj in self.queryset:
yield (obj.pk, self.get_label(obj), obj == self.data)
def process_formdata(self, valuelist):
if valuelist:
if valuelist[0] == '__None':
self.data = None
else:
self._data = None
self._formdata = int(valuelist[0])
def pre_validate(self, form):
if not self.allow_blank or self.data is not None:
for obj in self.queryset:
if self.data == obj:
break
else:
raise ValidationError(self.gettext('Not a valid choice'))
[docs]class ModelSelectField(QuerySetSelectField):
"""
Like a QuerySetSelectField, except takes a model class instead of a
queryset and lists everything in it.
"""
def __init__(self, label=None, validators=None, model=None, **kwargs):
super(ModelSelectField, self).__init__(label, validators, queryset=model._default_manager.all(), **kwargs)
class DateTimeField(fields.DateTimeField):
"""
Adds support for Django's timezone utilities.
Requires Django >= 1.5
"""
def __init__(self, *args, **kwargs):
if not has_timezone:
raise ImportError('DateTimeField requires Django >= 1.5')
super(DateTimeField, self).__init__(*args, **kwargs)
def process_formdata(self, valuelist):
super(DateTimeField, self).process_formdata(valuelist)
date = self.data
if settings.USE_TZ and date is not None and timezone.is_naive(date):
current_timezone = timezone.get_current_timezone()
self.data = timezone.make_aware(date, current_timezone)
def _value(self):
date = self.data
if settings.USE_TZ and isinstance(date, datetime.datetime) and timezone.is_aware(date):
self.data = timezone.localtime(date)
return super(DateTimeField, self)._value()
