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from django import forms
from django.forms import ValidationError
from django.core.signing import Signer, BadSignature
from django.contrib.postgres.fields import ArrayField
from django.forms.widgets import FILE_INPUT_CONTRADICTION
from django.forms.fields import CallableChoiceIterator
import pickle
import base64
from itertools import groupby
from .widgets import InlineImageUploadWidget, InlinePdfUploadWidget
from .widgets import LinkForCodeWidget, SubmitButtonWidget, SelectSetValueWidget
class _ValidatorField(forms.Field):
required = True
widget = forms.HiddenInput
class ConcurrentProtectedModelForm(forms.ModelForm):
_validator = _ValidatorField()
exclude_fields_from_validation = []
def _filter_initial(self):
# self.initial will include things given in the URL after ?, so filter it to
# only include items that are actually form fields.
return {k: v for k, v in list(self.initial.items()) if k in list(self.fields.keys()) and k not in self.exclude_fields_from_validation}
def update_protected_fields(self):
self.fields['_validator'].initial = Signer().sign(base64.urlsafe_b64encode(pickle.dumps(self._filter_initial(), -1)).decode('ascii'))
def __init__(self, *args, **kwargs):
r = super(ConcurrentProtectedModelForm, self).__init__(*args, **kwargs)
self.update_protected_fields()
return r
def clean(self):
# Process the form itself
data = super(ConcurrentProtectedModelForm, self).clean()
if not self.instance.pk:
# No primary key, means instance was not previously saved, so there can be
# no concurrent edit.
return data
# Fetch the list of values from the currernt object in the db
i = self._filter_initial()
try:
s = Signer().unsign(self.cleaned_data['_validator'])
b = base64.urlsafe_b64decode(s.encode('utf8'))
d = pickle.loads(b)
for k, v in list(d.items()):
if i[k] != v:
raise ValidationError("Concurrent modification of field {0}. Please reload the form and try again.".format(k))
except BadSignature:
raise ValidationError("Form has been tampered with!")
except TypeError:
raise ValidationError("Bad serialized form state")
except pickle.UnpicklingError:
raise ValidationError("Bad serialized python form state")
return data
class ChoiceArrayField(ArrayField):
def formfield(self, **kwargs):
defaults = {
'form_class': forms.MultipleChoiceField,
'choices': self.base_field.choices,
}
defaults.update(kwargs)
return super(ArrayField, self).formfield(**defaults)
class GroupedIterator(forms.models.ModelChoiceIterator):
def __iter__(self):
for group, choices in groupby(self.queryset.all().order_by(self.field.groupfield, *self.field.orderby),
key=lambda x: getattr(x, self.field.groupfield)):
yield (group,
[self.choice(c) for c in choices])
class Grouped(object):
def __init__(self, groupfield, queryset, *args, **kwargs):
self.orderby = queryset.query.order_by
super(Grouped, self).__init__(*args, queryset=queryset, **kwargs)
self.groupfield = groupfield
def _get_choices(self):
return GroupedIterator(self)
class GroupedModelMultipleChoiceField(Grouped, forms.ModelMultipleChoiceField):
choices = property(Grouped._get_choices, forms.ModelMultipleChoiceField._set_choices)
class IntegerBooleanField(forms.BooleanField):
def to_python(self, value):
return value and 1 or 0
def prepare_value(self, value):
return value and True or False
class CharToArrayField(forms.CharField):
def to_python(self, value):
return [x.strip() for x in value.split(',') if x.strip()]
def prepare_value(self, value):
if isinstance(value, list):
return ", ".join(value)
else:
return value
class ImageBinaryFormField(forms.Field):
widget = InlineImageUploadWidget
def to_python(self, value):
if value is False:
# Value gets set to False if the clear checkbox is marked
return None
if value == FILE_INPUT_CONTRADICTION:
# This gets set if the user *both* uploads a new file *and* marks the clear checkbox
return None
if value is None:
return None
return value.read()
def prepare_value(self, value):
return value
def clean(self, data, initial=None):
if data is False:
if not self.required:
return False
data = None
if not data and initial:
return initial
return super(ImageBinaryFormField, self).clean(data)
class PdfBinaryFormField(ImageBinaryFormField):
widget = InlinePdfUploadWidget
class LinkForCodeField(forms.Field):
widget = LinkForCodeWidget
class SubmitButtonField(forms.Field):
def __init__(self, *args, **kwargs):
if not kwargs:
kwargs = {}
self.callback = kwargs.pop('callback', None)
kwargs['widget'] = SubmitButtonWidget
prefixparagraph = kwargs.pop('prefixparagraph', None)
super().__init__(*args, **kwargs)
self.widget.label = kwargs.get('label', 'Unknown label')
self.widget.prefixparagraph = prefixparagraph
class SelectSetValueField(forms.ChoiceField):
widget = SelectSetValueWidget
def __init__(self, *args, **kwargs):
setvaluefield = kwargs.pop('setvaluefield')
self.__choices = kwargs.pop('choices')
if callable(self.__choices):
self.__choices = CallableChoiceIterator(self.__choices)
else:
self.__choices = list(self.__choices)
kwargs['choices'] = self._choices_slicer
super().__init__(*args, **kwargs)
self.widget.setvalues = {r[0]: (r[2], r[3]) for r in self.__choices}
self.widget.setvaluefield = setvaluefield
def _choices_slicer(self):
for r in self.__choices:
yield (r[0], r[1])
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