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# -*- coding: utf-8 -*-
forms for django-form-utils
Time-stamp: <2010-04-28 02:57:16 carljm>
from __future__ import unicode_literals
from copy import deepcopy
from django import forms
from django.forms.utils import flatatt, ErrorDict
except ImportError: # Django < 1.9 compatibility
from django.forms.util import flatatt, ErrorDict
from django.utils import six
from django.utils.safestring import mark_safe
def with_metaclass(meta, *bases):
"""Create a base class with a metaclass.
I'm not sure exactly why this is needed, but the implementation in six
changed (see
and the new version doesn't work here.
return meta(str("NewBase"), bases, {})
class Fieldset(object):
"""An iterable Fieldset with a legend and a set of BoundFields."""
def __init__(self, form, name, boundfields, legend='', classes='',
self.form = form
self.boundfields = boundfields
if legend is None:
legend = name
self.legend = legend and mark_safe(legend)
self.classes = classes
self.description = mark_safe(description) = name
def _errors(self):
return ErrorDict(((k, v) for (k, v) in six.iteritems(self.form.errors)
if k in [ for f in self.boundfields]))
errors = property(_errors)
def __iter__(self):
for bf in self.boundfields:
yield _mark_row_attrs(bf, self.form)
def __repr__(self):
return "%s('%s', %s, legend='%s', classes='%s', description='%s')" % (
[ for f in self.boundfields], self.legend, self.classes,
class FieldsetCollection(object):
def __init__(self, form, fieldsets):
self.form = form
self.fieldsets = fieldsets
self._cached_fieldsets = []
def __len__(self):
return len(self.fieldsets) or 1
def __iter__(self):
if not self._cached_fieldsets:
for field in self._cached_fieldsets:
yield field
def __getitem__(self, key):
if not self._cached_fieldsets:
for field in self._cached_fieldsets:
if == key:
return field
raise KeyError
def _gather_fieldsets(self):
if not self.fieldsets:
self.fieldsets = (('main', {'fields': self.form.fields.keys(),
'legend': ''}),)
for name, options in self.fieldsets:
field_names = [n for n in options['fields']
if n in self.form.fields]
except KeyError:
message = "Fieldset definition must include 'fields' option."
raise ValueError(message)
boundfields = [forms.forms.BoundField(self.form,
self.form.fields[n], n)
for n in field_names]
self._cached_fieldsets.append(Fieldset(self.form, name,
boundfields, options.get('legend', None),
' '.join(options.get('classes', ())),
options.get('description', '')))
def _get_meta_attr(attrs, attr, default):
ret = getattr(attrs['Meta'], attr)
except (KeyError, AttributeError):
ret = default
return ret
def _set_meta_attr(attrs, attr, value):
setattr(attrs['Meta'], attr, value)
return True
except KeyError:
return False
def get_fieldsets(bases, attrs):
"""Get the fieldsets definition from the inner Meta class."""
fieldsets = _get_meta_attr(attrs, 'fieldsets', None)
if fieldsets is None:
#grab the fieldsets from the first base class that has them
for base in bases:
fieldsets = getattr(base, 'base_fieldsets', None)
if fieldsets is not None:
fieldsets = fieldsets or []
return fieldsets
def get_fields_from_fieldsets(fieldsets):
"""Get a list of all fields included in a fieldsets definition."""
fields = []
for name, options in fieldsets:
except (TypeError, KeyError):
raise ValueError('"fieldsets" must be an iterable of two-tuples, '
'and the second tuple must be a dictionary '
'with a "fields" key')
return fields or None
def get_row_attrs(bases, attrs):
"""Get the row_attrs definition from the inner Meta class."""
return _get_meta_attr(attrs, 'row_attrs', {})
def _mark_row_attrs(bf, form):
row_attrs = deepcopy(form._row_attrs.get(, {}))
if bf.field.required:
req_class = 'required'
req_class = 'optional'
if bf.errors:
req_class += ' error'
if 'class' in row_attrs:
row_attrs['class'] = row_attrs['class'] + ' ' + req_class
row_attrs['class'] = req_class
bf.row_attrs = mark_safe(flatatt(row_attrs))
return bf
class BetterFormBaseMetaclass(type):
def __new__(cls, name, bases, attrs):
attrs['base_fieldsets'] = get_fieldsets(bases, attrs)
fields = get_fields_from_fieldsets(attrs['base_fieldsets'])
if (_get_meta_attr(attrs, 'fields', None) is None and
_get_meta_attr(attrs, 'exclude', None) is None):
_set_meta_attr(attrs, 'fields', fields)
attrs['base_row_attrs'] = get_row_attrs(bases, attrs)
new_class = super(BetterFormBaseMetaclass,
cls).__new__(cls, name, bases, attrs)
return new_class
class BetterFormMetaclass(BetterFormBaseMetaclass,
class BetterModelFormMetaclass(BetterFormBaseMetaclass,
class BetterBaseForm(object):
``BetterForm`` and ``BetterModelForm`` are subclasses of Form
and ModelForm that allow for declarative definition of fieldsets
and row_attrs in an inner Meta class.
The row_attrs declaration is a dictionary mapping field names to
dictionaries of attribute/value pairs. The attribute/value
dictionaries will be flattened into HTML-style attribute/values
(i.e. {'style': 'display: none'} will become ``style="display:
none"``), and will be available as the ``row_attrs`` attribute of
the ``BoundField``. Also, a CSS class of "required" or "optional"
will automatically be added to the row_attrs of each
``BoundField``, depending on whether the field is required.
There is no automatic inheritance of ``row_attrs``.
The fieldsets declaration is a list of two-tuples very similar to
the ``fieldsets`` option on a ModelAdmin class in
The first item in each two-tuple is a name for the fieldset, and
the second is a dictionary of fieldset options.
Valid fieldset options in the dictionary include:
``fields`` (required): A tuple of field names to display in this
``classes``: A list of extra CSS classes to apply to the fieldset.
``legend``: This value, if present, will be the contents of a ``legend``
tag to open the fieldset.
``description``: A string of optional extra text to be displayed
under the ``legend`` of the fieldset.
When iterated over, the ``fieldsets`` attribute of a
``BetterForm`` (or ``BetterModelForm``) yields ``Fieldset``s.
Each ``Fieldset`` has a ``name`` attribute, a ``legend``
attribute, , a ``classes`` attribute (the ``classes`` tuple
collapsed into a space-separated string), and a description
attribute, and when iterated over yields its ``BoundField``s.
Subclasses of a ``BetterForm`` will inherit their parent's
fieldsets unless they define their own.
A ``BetterForm`` or ``BetterModelForm`` can still be iterated over
directly to yield all of its ``BoundField``s, regardless of
def __init__(self, *args, **kwargs):
self._fieldsets = deepcopy(self.base_fieldsets)
self._row_attrs = deepcopy(self.base_row_attrs)
self._fieldset_collection = None
super(BetterBaseForm, self).__init__(*args, **kwargs)
def fieldsets(self):
if not self._fieldset_collection:
self._fieldset_collection = FieldsetCollection(
self, self._fieldsets)
return self._fieldset_collection
def __iter__(self):
for bf in super(BetterBaseForm, self).__iter__():
yield _mark_row_attrs(bf, self)
def __getitem__(self, name):
bf = super(BetterBaseForm, self).__getitem__(name)
return _mark_row_attrs(bf, self)
class BetterForm(with_metaclass(BetterFormMetaclass, BetterBaseForm),
__doc__ = BetterBaseForm.__doc__
class BetterModelForm(with_metaclass(BetterModelFormMetaclass,
BetterBaseForm), forms.ModelForm):
__doc__ = BetterBaseForm.__doc__
class BasePreviewFormMixin(object):
Mixin to add preview functionality to a form. If the form is submitted
with the following k/v pair in its ``data`` dictionary:
'submit': 'preview' (value string is case insensitive)
Then ``PreviewForm.preview`` will be marked ``True`` and the form will
be marked invalid (though this invalidation will not put an error in
its ``errors`` dictionary).
def __init__(self, *args, **kwargs):
super(BasePreviewFormMixin, self).__init__(*args, **kwargs)
self.preview = self.check_preview(kwargs.get('data', None))
def check_preview(self, data):
if data and data.get('submit', '').lower() == u'preview':
return True
return False
def is_valid(self, *args, **kwargs):
if self.preview:
return False
return super(BasePreviewFormMixin, self).is_valid()
class PreviewModelForm(BasePreviewFormMixin, BetterModelForm):
class PreviewForm(BasePreviewFormMixin, BetterForm):