TranslatableModelFormMetaclass.__new__() - Code Metrics - Inspection of "Merge pull request #135 from nephila/feature/fix_u..." - edoburu/django-parler - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Push — master ( 0bffe1...d6203d )

by Diederik van der

created 2016-05-04 11:48 UTC

TranslatableModelFormMetaclass.new() F

↳ Parent: TranslatableModelFormMetaclass

Complexity

Conditions

Size

Total Lines

Duplication

Lines	0
Ratio	0 %

Metric	Value
dl	0
loc	63
rs	2.9282
cc	19

How to fix Long Method Complexity

from django import forms
import django
from django.core.exceptions import ObjectDoesNotExist
from django.forms.forms import BoundField
from django.forms.models import ModelFormMetaclass, BaseInlineFormSet
from django.utils.functional import cached_property
from django.utils.translation import get_language
from django.utils import six
from parler.models import TranslationDoesNotExist
from parler.utils import compat


__all__ = (
    'TranslatableModelForm',
    'TranslatedField',
    'BaseTranslatableModelForm',
    #'TranslatableModelFormMetaclass',
)


class TranslatedField(object):
    """
    A wrapper for a translated form field.

    This wrapper can be used to declare translated fields on the form, e.g.

    .. code-block:: python

        class MyForm(TranslatableModelForm):
            title = TranslatedField()
            slug = TranslatedField()

            description = TranslatedField(form_class=forms.CharField, widget=TinyMCE)
    """

    def __init__(self, **kwargs):
        # The metaclass performs the magic replacement with the actual formfield.
        self.kwargs = kwargs


class BaseTranslatableModelForm(forms.BaseModelForm):
    """
    The base methods added to :class:`TranslatableModelForm` to fetch and store translated fields.
    """
    language_code = None    # Set by TranslatableAdmin.get_form() on the constructed subclass.

    def __init__(self, *args, **kwargs):
        current_language = kwargs.pop('_current_language', None)   # Used for TranslatableViewMixin
        super(BaseTranslatableModelForm, self).__init__(*args, **kwargs)

        # Load the initial values for the translated fields
        instance = kwargs.get('instance', None)
        if instance:
            for meta in instance._parler_meta:
                try:
                    # By not auto creating a model, any template code that reads the fields
                    # will continue to see one of the other translations.
                    # This also causes admin inlines to show the fallback title in __unicode__.
                    translation = instance._get_translated_model(meta=meta)
                except TranslationDoesNotExist:
                    pass
                else:
                    for field in meta.get_translated_fields():
                        try:
                            self.initial.setdefault(field, getattr(translation, field))
                        except ObjectDoesNotExist:
                            # This occurs when a ForeignKey field is part of the translation,
                            # but it's value is still not yet, and the field has null=False.
                            pass

        # Typically already set by admin
        if self.language_code is None:
            if instance:
                self.language_code = instance.get_current_language()
                return
            else:
                self.language_code = current_language or get_language()

    def _post_clean(self):
        # Copy the translated fields into the model
        # Make sure the language code is set as early as possible (so it's active during most clean() methods)
        self.instance.set_current_language(self.language_code)
        self.save_translated_fields()

        # Perform the regular clean checks, this also updates self.instance
        super(BaseTranslatableModelForm, self)._post_clean()

    def save_translated_fields(self):
        """
        Save all translated fields.
        """
        # Assign translated fields to the model (using the TranslatedAttribute descriptor)
        for field in self._translated_fields:
            try:
                value = self.cleaned_data[field]
            except KeyError:  # Field has a ValidationError
                continue
            setattr(self.instance, field, value)

    @cached_property
    def _translated_fields(self):
        field_names = self._meta.model._parler_meta.get_all_fields()
        return [f_name for f_name in field_names if f_name in self.fields]

    def __getitem__(self, name):
        """
        Return a :class:`TranslatableBoundField` for translated models.
        This extends the default ``form[field]`` interface that produces the BoundField for HTML templates.
        """
        boundfield = super(BaseTranslatableModelForm, self).__getitem__(name)
        if name in self._translated_fields:
            # Oh the wonders of Python :)
            boundfield.__class__ = _upgrade_boundfield_class(boundfield.__class__)
        return boundfield


UPGRADED_CLASSES = {}


def _upgrade_boundfield_class(cls):
    if cls is BoundField:
        return TranslatableBoundField
    elif issubclass(cls, TranslatableBoundField):
        return cls

    # When some other package also performs this same trick,
    # combine both classes on the fly. Avoid having to do that each time.
    # This is needed for django-slug-preview
    try:
        return UPGRADED_CLASSES[cls]
    except KeyError:
        # Create once
        new_cls = type('Translatable{0}'.format(cls.__name__), (cls, TranslatableBoundField), {})
        UPGRADED_CLASSES[cls] = new_cls
        return new_cls


class TranslatableBoundField(BoundField):
    """
    Decorating the regular BoundField to distinguish translatable fields in the admin.
    """
    #: A tagging attribute, making it easy for templates to identify these fields
    is_translatable = True

    def label_tag(self, contents=None, attrs=None, *args, **kwargs):  # extra args differ per Django version
        if attrs is None:
            attrs = {}

        attrs['class'] = (attrs.get('class', '') + " translatable-field").strip()
        return super(TranslatableBoundField, self).label_tag(contents, attrs, *args, **kwargs)

    # The as_widget() won't be overwritten to add a 'class' attr,
    # because it will overwrite what AdminTextInputWidget and fields have as default.


class TranslatableModelFormMetaclass(ModelFormMetaclass):
    """
    Meta class to add translated form fields to the form.
    """
    def __new__(mcs, name, bases, attrs):
        # Before constructing class, fetch attributes from bases list.
        form_meta = _get_mro_attribute(bases, '_meta')
        form_base_fields = _get_mro_attribute(bases, 'base_fields', {})  # set by previous class level.

        if form_meta:
            # Not declaring the base class itself, this is a subclass.

            # Read the model from the 'Meta' attribute. This even works in the admin,
            # as `modelform_factory()` includes a 'Meta' attribute.
            # The other options can be read from the base classes.
            form_new_meta = attrs.get('Meta', form_meta)
            form_model = form_new_meta.model if form_new_meta else form_meta.model

            # Detect all placeholders at this class level.
            placeholder_fields = [
                f_name for f_name, attr_value in six.iteritems(attrs) if isinstance(attr_value, TranslatedField)
            ]

            # Include the translated fields as attributes, pretend that these exist on the form.
            # This also works when assigning `form = TranslatableModelForm` in the admin,
            # since the admin always uses modelform_factory() on the form class, and therefore triggering this metaclass.
            if form_model:
                for translations_model in form_model._parler_meta.get_all_models():
                    fields = getattr(form_new_meta, 'fields', form_meta.fields)
                    exclude = getattr(form_new_meta, 'exclude', form_meta.exclude) or ()
                    widgets = getattr(form_new_meta, 'widgets', form_meta.widgets) or ()
                    formfield_callback = attrs.get('formfield_callback', None)

                    if fields == '__all__':
                        fields = None

                    for f_name in translations_model.get_translated_fields():
                        # Add translated field if not already added, and respect exclude options.
                        if f_name in placeholder_fields:
                            # The TranslatedField placeholder can be replaced directly with actual field, so do that.
                            attrs[f_name] = _get_model_form_field(translations_model, f_name, formfield_callback=formfield_callback, **attrs[f_name].kwargs)

                        # The next code holds the same logic as fields_for_model()
                        # The f.editable check happens in _get_model_form_field()
                        elif f_name not in form_base_fields \
                         and (fields is None or f_name in fields) \
                         and f_name not in exclude \
                         and not f_name in attrs:
                            # Get declared widget kwargs
                            if f_name in widgets:
                                # Not combined with declared fields (e.g. the TranslatedField placeholder)
                                kwargs = {'widget': widgets[f_name]}
                            else:
                                kwargs = {}

                            # See if this formfield was previously defined using a TranslatedField placeholder.
                            placeholder = _get_mro_attribute(bases, f_name)
                            if placeholder and isinstance(placeholder, TranslatedField):
                                kwargs.update(placeholder.kwargs)

                            # Add the form field as attribute to the class.
                            formfield = _get_model_form_field(translations_model, f_name, formfield_callback=formfield_callback, **kwargs)
                            if formfield is not None:
                                attrs[f_name] = formfield

        # Call the super class with updated `attrs` dict.
        return super(TranslatableModelFormMetaclass, mcs).__new__(mcs, name, bases, attrs)


def _get_mro_attribute(bases, name, default=None):
    for base in bases:
        try:
            return getattr(base, name)
        except AttributeError:
            continue
    return default


def _get_model_form_field(model, name, formfield_callback=None, **kwargs):
    """
    Utility to create the formfield from a model field.
    When a field is not editable, a ``None`` will be returned.
    """
    field = model._meta.get_field(name)
    if not field.editable:  # see fields_for_model() logic in Django.
        return None

    # Apply admin formfield_overrides
    if formfield_callback is None:
        formfield = field.formfield(**kwargs)
    elif not callable(formfield_callback):
        raise TypeError('formfield_callback must be a function or callable')
    else:
        formfield = formfield_callback(field, **kwargs)

    return formfield


if django.VERSION < (1, 5):
    # Django 1.4 doesn't recognize the use of with_metaclass.
    # This breaks the form initialization in modelform_factory()
    class TranslatableModelForm(BaseTranslatableModelForm, forms.ModelForm):
        __metaclass__ = TranslatableModelFormMetaclass
else:
    class TranslatableModelForm(compat.with_metaclass(TranslatableModelFormMetaclass, BaseTranslatableModelForm, forms.ModelForm)):
        """
        The model form to use for translated models.
        """

    # six.with_metaclass does not handle more than 2 parent classes for django < 1.6
    # but we need all of them in django 1.7 to pass check admin.E016:
    #       "The value of 'form' must inherit from 'BaseModelForm'"
    # so we use our copied version in parler.utils.compat
    #
    # Also, the class must inherit from ModelForm,
    # or the ModelFormMetaclass will skip initialization.
    # It only adds the _meta from anything that extends ModelForm.


class TranslatableBaseInlineFormSet(BaseInlineFormSet):
    """
    The formset base for creating inlines with translatable models.
    """
    language_code = None

    def _construct_form(self, i, **kwargs):
        form = super(TranslatableBaseInlineFormSet, self)._construct_form(i, **kwargs)
        form.language_code = self.language_code   # Pass the language code for new objects!
        return form

    def save_new(self, form, commit=True):
        obj = super(TranslatableBaseInlineFormSet, self).save_new(form, commit)
        return obj


# Backwards compatibility
TranslatableModelFormMixin = BaseTranslatableModelForm


1			from django import forms
2			import django
3			from django.core.exceptions import ObjectDoesNotExist
4			from django.forms.forms import BoundField
5			from django.forms.models import ModelFormMetaclass, BaseInlineFormSet
6			from django.utils.functional import cached_property
7			from django.utils.translation import get_language
8			from django.utils import six
9			from parler.models import TranslationDoesNotExist
10			from parler.utils import compat
11
12
13			__all__ = (
14			'TranslatableModelForm',
15			'TranslatedField',
16			'BaseTranslatableModelForm',
17			#'TranslatableModelFormMetaclass',
18			)
19
20
21			class TranslatedField(object):
22			"""
23			A wrapper for a translated form field.
24
25			This wrapper can be used to declare translated fields on the form, e.g.
26
27			.. code-block:: python
28
29			class MyForm(TranslatableModelForm):
30			title = TranslatedField()
31			slug = TranslatedField()
32
33			description = TranslatedField(form_class=forms.CharField, widget=TinyMCE)
34			"""
35
36			def __init__(self, **kwargs):
37			# The metaclass performs the magic replacement with the actual formfield.
38			self.kwargs = kwargs
39
40
41			class BaseTranslatableModelForm(forms.BaseModelForm):
42			"""
43			The base methods added to :class:`TranslatableModelForm` to fetch and store translated fields.
44			"""
45			language_code = None # Set by TranslatableAdmin.get_form() on the constructed subclass.
46
47			def __init__(self, args, *kwargs):
48			current_language = kwargs.pop('_current_language', None) # Used for TranslatableViewMixin
49			super(BaseTranslatableModelForm, self).__init__(args, *kwargs)
50
51			# Load the initial values for the translated fields
52			instance = kwargs.get('instance', None)
53			if instance:
54			for meta in instance._parler_meta:
55			try:
56			# By not auto creating a model, any template code that reads the fields
57			# will continue to see one of the other translations.
58			# This also causes admin inlines to show the fallback title in __unicode__.
59			translation = instance._get_translated_model(meta=meta)
60			except TranslationDoesNotExist:
61			pass
62			else:
63			for field in meta.get_translated_fields():
64			try:
65			self.initial.setdefault(field, getattr(translation, field))
66			except ObjectDoesNotExist:
67			# This occurs when a ForeignKey field is part of the translation,
68			# but it's value is still not yet, and the field has null=False.
69			pass
70
71			# Typically already set by admin
72			if self.language_code is None:
73			if instance:
74			self.language_code = instance.get_current_language()
75			return
76			else:
77			self.language_code = current_language or get_language()
78
79			def _post_clean(self):
80			# Copy the translated fields into the model
81			# Make sure the language code is set as early as possible (so it's active during most clean() methods)
82			self.instance.set_current_language(self.language_code)
83			self.save_translated_fields()
84
85			# Perform the regular clean checks, this also updates self.instance
86			super(BaseTranslatableModelForm, self)._post_clean()
87
88			def save_translated_fields(self):
89			"""
90			Save all translated fields.
91			"""
92			# Assign translated fields to the model (using the TranslatedAttribute descriptor)
93			for field in self._translated_fields:
94			try:
95			value = self.cleaned_data[field]
96			except KeyError: # Field has a ValidationError
97			continue
98			setattr(self.instance, field, value)
99
100			@cached_property
101			def _translated_fields(self):
102			field_names = self._meta.model._parler_meta.get_all_fields()
103			return [f_name for f_name in field_names if f_name in self.fields]
104
105			def __getitem__(self, name):
106			"""
107			Return a :class:`TranslatableBoundField` for translated models.
108			This extends the default ``form[field]`` interface that produces the BoundField for HTML templates.
109			"""
110			boundfield = super(BaseTranslatableModelForm, self).__getitem__(name)
111			if name in self._translated_fields:
112			# Oh the wonders of Python :)
113			boundfield.__class__ = _upgrade_boundfield_class(boundfield.__class__)
114			return boundfield
115
116
117			UPGRADED_CLASSES = {}
118
119
120			def _upgrade_boundfield_class(cls):
121			if cls is BoundField:
122			return TranslatableBoundField
123			elif issubclass(cls, TranslatableBoundField):
124			return cls
125
126			# When some other package also performs this same trick,
127			# combine both classes on the fly. Avoid having to do that each time.
128			# This is needed for django-slug-preview
129			try:
130			return UPGRADED_CLASSES[cls]
131			except KeyError:
132			# Create once
133			new_cls = type('Translatable{0}'.format(cls.__name__), (cls, TranslatableBoundField), {})
134			UPGRADED_CLASSES[cls] = new_cls
135			return new_cls
136
137
138			class TranslatableBoundField(BoundField):
139			"""
140			Decorating the regular BoundField to distinguish translatable fields in the admin.
141			"""
142			#: A tagging attribute, making it easy for templates to identify these fields
143			is_translatable = True
144
145			def label_tag(self, contents=None, attrs=None, args, *kwargs): # extra args differ per Django version
146			if attrs is None:
147			attrs = {}
148
149			attrs['class'] = (attrs.get('class', '') + " translatable-field").strip()
150			return super(TranslatableBoundField, self).label_tag(contents, attrs, args, *kwargs)
151
152			# The as_widget() won't be overwritten to add a 'class' attr,
153			# because it will overwrite what AdminTextInputWidget and fields have as default.
154
155
156			class TranslatableModelFormMetaclass(ModelFormMetaclass):
157			"""
158			Meta class to add translated form fields to the form.
159			"""
160			def __new__(mcs, name, bases, attrs):
161			# Before constructing class, fetch attributes from bases list.
162			form_meta = _get_mro_attribute(bases, '_meta')
163			form_base_fields = _get_mro_attribute(bases, 'base_fields', {}) # set by previous class level.
164
165			if form_meta:
166			# Not declaring the base class itself, this is a subclass.
167
168			# Read the model from the 'Meta' attribute. This even works in the admin,
169			# as `modelform_factory()` includes a 'Meta' attribute.
170			# The other options can be read from the base classes.
171			form_new_meta = attrs.get('Meta', form_meta)
172			form_model = form_new_meta.model if form_new_meta else form_meta.model
173
174			# Detect all placeholders at this class level.
175			placeholder_fields = [
176			f_name for f_name, attr_value in six.iteritems(attrs) if isinstance(attr_value, TranslatedField)
177			]
178
179			# Include the translated fields as attributes, pretend that these exist on the form.
180			# This also works when assigning `form = TranslatableModelForm` in the admin,
181			# since the admin always uses modelform_factory() on the form class, and therefore triggering this metaclass.
182			if form_model:
183			for translations_model in form_model._parler_meta.get_all_models():
184			fields = getattr(form_new_meta, 'fields', form_meta.fields)
185			exclude = getattr(form_new_meta, 'exclude', form_meta.exclude) or ()
186			widgets = getattr(form_new_meta, 'widgets', form_meta.widgets) or ()
187			formfield_callback = attrs.get('formfield_callback', None)
188
189			if fields == '__all__':
190			fields = None
191
192			for f_name in translations_model.get_translated_fields():
193			# Add translated field if not already added, and respect exclude options.
194			if f_name in placeholder_fields:
195			# The TranslatedField placeholder can be replaced directly with actual field, so do that.
196			attrs[f_name] = _get_model_form_field(translations_model, f_name, formfield_callback=formfield_callback, **attrs[f_name].kwargs)
197
198			# The next code holds the same logic as fields_for_model()
199			# The f.editable check happens in _get_model_form_field()
200			elif f_name not in form_base_fields \
201			and (fields is None or f_name in fields) \
202			and f_name not in exclude \
203			and not f_name in attrs:
204			# Get declared widget kwargs
205			if f_name in widgets:
206			# Not combined with declared fields (e.g. the TranslatedField placeholder)
207			kwargs = {'widget': widgets[f_name]}
208			else:
209			kwargs = {}
210
211			# See if this formfield was previously defined using a TranslatedField placeholder.
212			placeholder = _get_mro_attribute(bases, f_name)
213			if placeholder and isinstance(placeholder, TranslatedField):
214			kwargs.update(placeholder.kwargs)
215
216			# Add the form field as attribute to the class.
217			formfield = _get_model_form_field(translations_model, f_name, formfield_callback=formfield_callback, **kwargs)
218			if formfield is not None:
219			attrs[f_name] = formfield
220
221			# Call the super class with updated `attrs` dict.
222			return super(TranslatableModelFormMetaclass, mcs).__new__(mcs, name, bases, attrs)
223
224
225			def _get_mro_attribute(bases, name, default=None):
226			for base in bases:
227			try:
228			return getattr(base, name)
229			except AttributeError:
230			continue
231			return default
232
233
234			def _get_model_form_field(model, name, formfield_callback=None, **kwargs):
235			"""
236			Utility to create the formfield from a model field.
237			When a field is not editable, a ``None`` will be returned.
238			"""
239			field = model._meta.get_field(name)
240			if not field.editable: # see fields_for_model() logic in Django.
241			return None
242
243			# Apply admin formfield_overrides
244			if formfield_callback is None:
245			formfield = field.formfield(**kwargs)
246			elif not callable(formfield_callback):
247			raise TypeError('formfield_callback must be a function or callable')
248			else:
249			formfield = formfield_callback(field, **kwargs)
250
251			return formfield
252
253
254			if django.VERSION < (1, 5):
255			# Django 1.4 doesn't recognize the use of with_metaclass.
256			# This breaks the form initialization in modelform_factory()
257			class TranslatableModelForm(BaseTranslatableModelForm, forms.ModelForm):
258			__metaclass__ = TranslatableModelFormMetaclass
259			else:
260			class TranslatableModelForm(compat.with_metaclass(TranslatableModelFormMetaclass, BaseTranslatableModelForm, forms.ModelForm)):
261			"""
262			The model form to use for translated models.
263			"""
264
265			# six.with_metaclass does not handle more than 2 parent classes for django < 1.6
266			# but we need all of them in django 1.7 to pass check admin.E016:
267			# "The value of 'form' must inherit from 'BaseModelForm'"
268			# so we use our copied version in parler.utils.compat
269			#
270			# Also, the class must inherit from ModelForm,
271			# or the ModelFormMetaclass will skip initialization.
272			# It only adds the _meta from anything that extends ModelForm.
273
274
275			class TranslatableBaseInlineFormSet(BaseInlineFormSet):
276			"""
277			The formset base for creating inlines with translatable models.
278			"""
279			language_code = None
280
281			def _construct_form(self, i, **kwargs):
282			form = super(TranslatableBaseInlineFormSet, self)._construct_form(i, **kwargs)
283			form.language_code = self.language_code # Pass the language code for new objects!
284			return form
285
286			def save_new(self, form, commit=True):
287			obj = super(TranslatableBaseInlineFormSet, self).save_new(form, commit)
288			return obj
289
290
291			# Backwards compatibility
292			TranslatableModelFormMixin = BaseTranslatableModelForm
293

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