ViewUrlMixin.get_context_data() - Code Metrics - Inspection of "Fix #133" - edoburu/django-parler - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Pull Request — master (#135)

by Iacopo

created 2016-04-19 22:57 UTC

ViewUrlMixin.get_context_data() A

↳ Parent: ViewUrlMixin

Complexity

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Metric	Value
dl	0
loc	4
rs	10
cc	2

"""
The views provide high-level utilities to integrate translation support into other projects.

The following mixins are available:

* :class:`ViewUrlMixin` - provide a ``get_view_url`` for the :ref:`{% get_translated_url %} <get_translated_url>` template tag.
* :class:`TranslatableSlugMixin` - enrich the :class:`~django.views.generic.detail.DetailView` to support translatable slugs.
* :class:`LanguageChoiceMixin` - add ``?language=xx`` support to a view (e.g. for editing).
* :class:`TranslatableModelFormMixin` - add support for translatable forms, e.g. for creating/updating objects.

The following views are available:

* :class:`TranslatableCreateView` - The :class:`~django.views.generic.edit.CreateView` with :class:`TranslatableModelFormMixin` support.
* :class:`TranslatableUpdateView` - The :class:`~django.views.generic.edit.UpdateView` with :class:`TranslatableModelFormMixin` support.
"""
from __future__ import unicode_literals
import django
from django.core.exceptions import ImproperlyConfigured, ObjectDoesNotExist
from django.core.urlresolvers import reverse
from django.forms.models import modelform_factory
from django.http import Http404, HttpResponsePermanentRedirect
from django.utils import translation
from django.views import generic
from django.views.generic.edit import ModelFormMixin
from parler.forms import TranslatableModelForm
from parler.models import TranslatableModelMixin
from parler.utils import get_active_language_choices
from parler.utils.context import switch_language
from parler.utils.views import get_language_parameter, get_language_tabs

__all__ = (
    'ViewUrlMixin',
    'TranslatableSlugMixin',
    'LanguageChoiceMixin',
    'TranslatableModelFormMixin',
    'TranslatableCreateView',
    'TranslatableUpdateView',
)


class ViewUrlMixin(object):
    """
    Provide a ``view.get_view_url`` method in the template.

    This tells the template what the exact canonical URL should be of a view.
    The :ref:`{% get_translated_url %} <get_translated_url>` template tag uses this
    to find the proper translated URL of the current page.

    Typically, setting the :attr:`view_url_name` just works::

        class ArticleListView(ViewUrlMixin, ListView):
            view_url_name = 'article:list'

    The :func:`get_view_url` will use the :attr:`view_url_name` together
    with ``view.args`` and ``view.kwargs`` construct the URL.
    When some arguments are translated (e.g. a slug), the :func:`get_view_url`
    can be overwritten to generate the proper URL::

        from parler.views import ViewUrlMixin, TranslatableUpdateView
        from parler.utils.context import switch_language

        class ArticleEditView(ViewUrlMixin, TranslatableUpdateView):
            view_url_name = 'article:edit'

            def get_view_url(self):
                with switch_language(self.object, get_language()):
                    return reverse(self.view_url_name, kwargs={'slug': self.object.slug})
    """
    #: The default view name used by :func:`get_view_url`, which
    #: should correspond with the view name in the URLConf.
    view_url_name = None

    def get_view_url(self):
        """
        This method is used by the ``get_translated_url`` template tag.

        By default, it uses the :attr:`view_url_name` to generate an URL.
        When the URL ``args`` and ``kwargs`` are translatable,
        override this function instead to generate the proper URL.
        """
        if not self.view_url_name:
            # Sadly, class based views can't work with reverse(func_pointer) as that's unknown.
            # Neither is it possible to use resolve(self.request.path).view_name in this function as auto-detection.
            # This function can be called in the context of a different language.
            # When i18n_patterns() is applied, that resolve() will fail.
            #
            # Hence, you need to provide a "view_url_name" as static configuration option.
            raise ImproperlyConfigured("Missing `view_url_name` attribute on {0}".format(self.__class__.__name__))

        return reverse(self.view_url_name, args=self.args, kwargs=self.kwargs)

    if django.VERSION < (1, 5):
        # The `get_translated_url` tag relies on the fact that the template can access the view again.
        # This was not possible until Django 1.5, so provide the `ContextMixin` logic for earlier Django versions.

        def get_context_data(self, **kwargs):
            if 'view' not in kwargs:
                kwargs['view'] = self
            return kwargs


class TranslatableSlugMixin(object):
    """
    An enhancement for the :class:`~django.views.generic.DetailView` to deal with translated slugs.
    This view makes sure that:

    * The object is fetched in the proper translation.
    * The slug field is read from the translation model, instead of the shared model.
    * Fallback languages are handled.
    * Objects are not accidentally displayed in their fallback slug, but redirect to the translated slug.

    Example:

    .. code-block:: python

        class ArticleDetailView(TranslatableSlugMixin, DetailView):
            model = Article
            template_name = 'article/details.html'
    """

    def get_translated_filters(self, slug):
        """
        Allow passing other filters for translated fields.
        """
        return {
            self.get_slug_field(): slug
        }

    def get_language(self):
        """
        Define the language of the current view, defaults to the active language.
        """
        return translation.get_language()

    def get_language_choices(self):
        """
        Define the language choices for the view, defaults to the defined settings.
        """
        return get_active_language_choices(self.get_language())

    def dispatch(self, request, *args, **kwargs):
        try:
            return super(TranslatableSlugMixin, self).dispatch(request, *args, **kwargs)
        except FallbackLanguageResolved as e:
            # Handle the fallback language redirect for get_object()
            with switch_language(e.object, e.correct_language):
                return HttpResponsePermanentRedirect(e.object.get_absolute_url())

    def get_object(self, queryset=None):
        """
        Fetch the object using a translated slug.
        """
        if queryset is None:
            queryset = self.get_queryset()

        slug = self.kwargs[self.slug_url_kwarg]
        choices = self.get_language_choices()

        obj = None
        using_fallback = False
        prev_choices = []
        for lang_choice in choices:
            try:
                # Get the single item from the filtered queryset
                # NOTE. Explicitly set language to the state the object was fetched in.
                filters = self.get_translated_filters(slug=slug)
                obj = queryset.translated(lang_choice, **filters).language(lang_choice).get()
            except ObjectDoesNotExist:
                # Translated object not found, next object is marked as fallback.
                using_fallback = True
                prev_choices.append(lang_choice)
            else:
                break

        if obj is None:
            tried_msg = ", tried languages: {0}".format(", ".join(choices))
            error_message = translation.ugettext("No %(verbose_name)s found matching the query") % {'verbose_name': queryset.model._meta.verbose_name}
            raise Http404(error_message + tried_msg)

        # Object found!
        if using_fallback:
            # It could happen that objects are resolved using their fallback language,
            # but the actual translation also exists. Either that means this URL should
            # raise a 404, or a redirect could be made as service to the users.
            # It's possible that the old URL was active before in the language domain/subpath
            # when there was no translation yet.
            for prev_choice in prev_choices:
                if obj.has_translation(prev_choice):
                    # Only dispatch() and render_to_response() can return a valid response,
                    # By breaking out here, this functionality can't be broken by users overriding render_to_response()
                    raise FallbackLanguageResolved(obj, prev_choice)

        return obj


class FallbackLanguageResolved(Exception):
    """
    An object was resolved in the fallback language, while it could be in the normal language.
    This exception is used internally to control code flow.
    """

    def __init__(self, object, correct_language):
        self.object = object
        self.correct_language = correct_language


class LanguageChoiceMixin(object):
    """
    Mixin to add language selection support to class based views, particularly create and update views.
    It adds support for the ``?language=..`` parameter in the query string, and tabs in the context.
    """
    query_language_key = 'language'

    def get_object(self, queryset=None):
        """
        Assign the language for the retrieved object.
        """
        object = super(LanguageChoiceMixin, self).get_object(queryset)
        if isinstance(object, TranslatableModelMixin):
            object.set_current_language(self.get_language(), initialize=True)
        return object

    def get_language(self):
        """
        Get the language parameter from the current request.
        """
        return get_language_parameter(self.request, self.query_language_key, default=self.get_default_language(object=object))

    def get_default_language(self, object=None):
        """
        Return the default language to use, if no language parameter is given.
        By default, it uses the default parler-language.
        """
        # Some users may want to override this, to return get_language()
        return None

    def get_current_language(self):
        """
        Return the current language for the currently displayed object fields.
        This reads ``self.object.get_current_language()`` and falls back to :func:`get_language`.
        """
        if self.object is not None:
            return self.object.get_current_language()
        else:
            return self.get_language()

    def get_context_data(self, **kwargs):
        context = super(LanguageChoiceMixin, self).get_context_data(**kwargs)
        context['language_tabs'] = self.get_language_tabs()
        return context

    def get_language_tabs(self):
        """
        Determine the language tabs to show.
        """
        current_language = self.get_current_language()
        if self.object:
            available_languages = list(self.object.get_available_languages())
        else:
            available_languages = []

        return get_language_tabs(self.request, current_language, available_languages)


class TranslatableModelFormMixin(LanguageChoiceMixin):
    """
    Mixin to add translation support to class based views.

    For example, adding translation support to django-oscar::

        from oscar.apps.dashboard.catalogue import views as oscar_views
        from parler.views import TranslatableModelFormMixin

        class ProductCreateUpdateView(TranslatableModelFormMixin, oscar_views.ProductCreateUpdateView):
            pass
    """

    def get_form_class(self):
        """
        Return a ``TranslatableModelForm`` by default if no form_class is set.
        """
        super_method = super(TranslatableModelFormMixin, self).get_form_class
        # no "__func__" on the class level function in python 3
        default_method = getattr(ModelFormMixin.get_form_class, '__func__', ModelFormMixin.get_form_class)
        if not (super_method.__func__ is default_method):
            # Don't get in your way, if you've overwritten stuff.
            return super_method()
        else:
            # Same logic as ModelFormMixin.get_form_class, but using the right form base class.
            if self.form_class:
                return self.form_class
            else:
                model = _get_view_model(self)
                return modelform_factory(model, form=TranslatableModelForm)

    def get_form_kwargs(self):
        """
        Pass the current language to the form.
        """
        kwargs = super(TranslatableModelFormMixin, self).get_form_kwargs()
        # The TranslatableAdmin can set form.language_code, because the modeladmin always creates a fresh subclass.
        # If that would be done here, the original globally defined form class would be updated.
        kwargs['_current_language'] = self.get_form_language()
        return kwargs

    # Backwards compatibility
    # Make sure overriding get_current_language() affects get_form_language() too.
    def get_form_language(self):
        return self.get_current_language()


# For the lazy ones:
class TranslatableCreateView(TranslatableModelFormMixin, generic.CreateView):
    """
    Create view that supports translated models.
    This is a mix of the :class:`TranslatableModelFormMixin`
    and Django's :class:`~django.views.generic.edit.CreateView`.
    """
    pass


class TranslatableUpdateView(TranslatableModelFormMixin, generic.UpdateView):
    """
    Update view that supports translated models.
    This is a mix of the :class:`TranslatableModelFormMixin`
    and Django's :class:`~django.views.generic.edit.UpdateView`.
    """
    pass


def _get_view_model(self):
    if self.model is not None:
        # If a model has been explicitly provided, use it
        return self.model
    elif hasattr(self, 'object') and self.object is not None:
        # If this view is operating on a single object, use the class of that object
        return self.object.__class__
    else:
        # Try to get a queryset and extract the model class from that
        return self.get_queryset().model


# Backwards compatibility
TranslatableSingleObjectMixin = LanguageChoiceMixin


1			"""
2			The views provide high-level utilities to integrate translation support into other projects.
3
4			The following mixins are available:
5
6			* :class:`ViewUrlMixin` - provide a ``get_view_url`` for the :ref:`{% get_translated_url %} <get_translated_url>` template tag.
7			* :class:`TranslatableSlugMixin` - enrich the :class:`~django.views.generic.detail.DetailView` to support translatable slugs.
8			* :class:`LanguageChoiceMixin` - add ``?language=xx`` support to a view (e.g. for editing).
9			* :class:`TranslatableModelFormMixin` - add support for translatable forms, e.g. for creating/updating objects.
10
11			The following views are available:
12
13			* :class:`TranslatableCreateView` - The :class:`~django.views.generic.edit.CreateView` with :class:`TranslatableModelFormMixin` support.
14			* :class:`TranslatableUpdateView` - The :class:`~django.views.generic.edit.UpdateView` with :class:`TranslatableModelFormMixin` support.
15			"""
16			from __future__ import unicode_literals
17			import django
18			from django.core.exceptions import ImproperlyConfigured, ObjectDoesNotExist
19			from django.core.urlresolvers import reverse
20			from django.forms.models import modelform_factory
21			from django.http import Http404, HttpResponsePermanentRedirect
22			from django.utils import translation
23			from django.views import generic
24			from django.views.generic.edit import ModelFormMixin
25			from parler.forms import TranslatableModelForm
26			from parler.models import TranslatableModelMixin
27			from parler.utils import get_active_language_choices
28			from parler.utils.context import switch_language
29			from parler.utils.views import get_language_parameter, get_language_tabs
30
31			__all__ = (
32			'ViewUrlMixin',
33			'TranslatableSlugMixin',
34			'LanguageChoiceMixin',
35			'TranslatableModelFormMixin',
36			'TranslatableCreateView',
37			'TranslatableUpdateView',
38			)
39
40
41			class ViewUrlMixin(object):
42			"""
43			Provide a ``view.get_view_url`` method in the template.
44
45			This tells the template what the exact canonical URL should be of a view.
46			The :ref:`{% get_translated_url %} <get_translated_url>` template tag uses this
47			to find the proper translated URL of the current page.
48
49			Typically, setting the :attr:`view_url_name` just works::
50
51			class ArticleListView(ViewUrlMixin, ListView):
52			view_url_name = 'article:list'
53
54			The :func:`get_view_url` will use the :attr:`view_url_name` together
55			with ``view.args`` and ``view.kwargs`` construct the URL.
56			When some arguments are translated (e.g. a slug), the :func:`get_view_url`
57			can be overwritten to generate the proper URL::
58
59			from parler.views import ViewUrlMixin, TranslatableUpdateView
60			from parler.utils.context import switch_language
61
62			class ArticleEditView(ViewUrlMixin, TranslatableUpdateView):
63			view_url_name = 'article:edit'
64
65			def get_view_url(self):
66			with switch_language(self.object, get_language()):
67			return reverse(self.view_url_name, kwargs={'slug': self.object.slug})
68			"""
69			#: The default view name used by :func:`get_view_url`, which
70			#: should correspond with the view name in the URLConf.
71			view_url_name = None
72
73			def get_view_url(self):
74			"""
75			This method is used by the ``get_translated_url`` template tag.
76
77			By default, it uses the :attr:`view_url_name` to generate an URL.
78			When the URL ``args`` and ``kwargs`` are translatable,
79			override this function instead to generate the proper URL.
80			"""
81			if not self.view_url_name:
82			# Sadly, class based views can't work with reverse(func_pointer) as that's unknown.
83			# Neither is it possible to use resolve(self.request.path).view_name in this function as auto-detection.
84			# This function can be called in the context of a different language.
85			# When i18n_patterns() is applied, that resolve() will fail.
86			#
87			# Hence, you need to provide a "view_url_name" as static configuration option.
88			raise ImproperlyConfigured("Missing `view_url_name` attribute on {0}".format(self.__class__.__name__))
89
90			return reverse(self.view_url_name, args=self.args, kwargs=self.kwargs)
91
92			if django.VERSION < (1, 5):
93			# The `get_translated_url` tag relies on the fact that the template can access the view again.
94			# This was not possible until Django 1.5, so provide the `ContextMixin` logic for earlier Django versions.
95
96			def get_context_data(self, **kwargs):
97			if 'view' not in kwargs:
98			kwargs['view'] = self
99			return kwargs
100
101
102			class TranslatableSlugMixin(object):
103			"""
104			An enhancement for the :class:`~django.views.generic.DetailView` to deal with translated slugs.
105			This view makes sure that:
106
107			* The object is fetched in the proper translation.
108			* The slug field is read from the translation model, instead of the shared model.
109			* Fallback languages are handled.
110			* Objects are not accidentally displayed in their fallback slug, but redirect to the translated slug.
111
112			Example:
113
114			.. code-block:: python
115
116			class ArticleDetailView(TranslatableSlugMixin, DetailView):
117			model = Article
118			template_name = 'article/details.html'
119			"""
120
121			def get_translated_filters(self, slug):
122			"""
123			Allow passing other filters for translated fields.
124			"""
125			return {
126			self.get_slug_field(): slug
127			}
128
129			def get_language(self):
130			"""
131			Define the language of the current view, defaults to the active language.
132			"""
133			return translation.get_language()
134
135			def get_language_choices(self):
136			"""
137			Define the language choices for the view, defaults to the defined settings.
138			"""
139			return get_active_language_choices(self.get_language())
140
141			def dispatch(self, request, args, *kwargs):
142			try:
143			return super(TranslatableSlugMixin, self).dispatch(request, args, *kwargs)
144			except FallbackLanguageResolved as e:
145			# Handle the fallback language redirect for get_object()
146			with switch_language(e.object, e.correct_language):
147			return HttpResponsePermanentRedirect(e.object.get_absolute_url())
148
149			def get_object(self, queryset=None):
150			"""
151			Fetch the object using a translated slug.
152			"""
153			if queryset is None:
154			queryset = self.get_queryset()
155
156			slug = self.kwargs[self.slug_url_kwarg]
157			choices = self.get_language_choices()
158
159			obj = None
160			using_fallback = False
161			prev_choices = []
162			for lang_choice in choices:
163			try:
164			# Get the single item from the filtered queryset
165			# NOTE. Explicitly set language to the state the object was fetched in.
166			filters = self.get_translated_filters(slug=slug)
167			obj = queryset.translated(lang_choice, **filters).language(lang_choice).get()
168			except ObjectDoesNotExist:
169			# Translated object not found, next object is marked as fallback.
170			using_fallback = True
171			prev_choices.append(lang_choice)
172			else:
173			break
174
175			if obj is None:
176			tried_msg = ", tried languages: {0}".format(", ".join(choices))
177			error_message = translation.ugettext("No %(verbose_name)s found matching the query") % {'verbose_name': queryset.model._meta.verbose_name}
178			raise Http404(error_message + tried_msg)
179
180			# Object found!
181			if using_fallback:
182			# It could happen that objects are resolved using their fallback language,
183			# but the actual translation also exists. Either that means this URL should
184			# raise a 404, or a redirect could be made as service to the users.
185			# It's possible that the old URL was active before in the language domain/subpath
186			# when there was no translation yet.
187			for prev_choice in prev_choices:
188			if obj.has_translation(prev_choice):
189			# Only dispatch() and render_to_response() can return a valid response,
190			# By breaking out here, this functionality can't be broken by users overriding render_to_response()
191			raise FallbackLanguageResolved(obj, prev_choice)
192
193			return obj
194
195
196			class FallbackLanguageResolved(Exception):
197			"""
198			An object was resolved in the fallback language, while it could be in the normal language.
199			This exception is used internally to control code flow.
200			"""
201
202			def __init__(self, object, correct_language):
203			self.object = object
204			self.correct_language = correct_language
205
206
207			class LanguageChoiceMixin(object):
208			"""
209			Mixin to add language selection support to class based views, particularly create and update views.
210			It adds support for the ``?language=..`` parameter in the query string, and tabs in the context.
211			"""
212			query_language_key = 'language'
213
214			def get_object(self, queryset=None):
215			"""
216			Assign the language for the retrieved object.
217			"""
218			object = super(LanguageChoiceMixin, self).get_object(queryset)
219			if isinstance(object, TranslatableModelMixin):
220			object.set_current_language(self.get_language(), initialize=True)
221			return object
222
223			def get_language(self):
224			"""
225			Get the language parameter from the current request.
226			"""
227			return get_language_parameter(self.request, self.query_language_key, default=self.get_default_language(object=object))
228
229			def get_default_language(self, object=None):
230			"""
231			Return the default language to use, if no language parameter is given.
232			By default, it uses the default parler-language.
233			"""
234			# Some users may want to override this, to return get_language()
235			return None
236
237			def get_current_language(self):
238			"""
239			Return the current language for the currently displayed object fields.
240			This reads ``self.object.get_current_language()`` and falls back to :func:`get_language`.
241			"""
242			if self.object is not None:
243			return self.object.get_current_language()
244			else:
245			return self.get_language()
246
247			def get_context_data(self, **kwargs):
248			context = super(LanguageChoiceMixin, self).get_context_data(**kwargs)
249			context['language_tabs'] = self.get_language_tabs()
250			return context
251
252			def get_language_tabs(self):
253			"""
254			Determine the language tabs to show.
255			"""
256			current_language = self.get_current_language()
257			if self.object:
258			available_languages = list(self.object.get_available_languages())
259			else:
260			available_languages = []
261
262			return get_language_tabs(self.request, current_language, available_languages)
263
264
265			class TranslatableModelFormMixin(LanguageChoiceMixin):
266			"""
267			Mixin to add translation support to class based views.
268
269			For example, adding translation support to django-oscar::
270
271			from oscar.apps.dashboard.catalogue import views as oscar_views
272			from parler.views import TranslatableModelFormMixin
273
274			class ProductCreateUpdateView(TranslatableModelFormMixin, oscar_views.ProductCreateUpdateView):
275			pass
276			"""
277
278			def get_form_class(self):
279			"""
280			Return a ``TranslatableModelForm`` by default if no form_class is set.
281			"""
282			super_method = super(TranslatableModelFormMixin, self).get_form_class
283			# no "__func__" on the class level function in python 3
284			default_method = getattr(ModelFormMixin.get_form_class, '__func__', ModelFormMixin.get_form_class)
285			if not (super_method.__func__ is default_method):
286			# Don't get in your way, if you've overwritten stuff.
287			return super_method()
288			else:
289			# Same logic as ModelFormMixin.get_form_class, but using the right form base class.
290			if self.form_class:
291			return self.form_class
292			else:
293			model = _get_view_model(self)
294			return modelform_factory(model, form=TranslatableModelForm)
295
296			def get_form_kwargs(self):
297			"""
298			Pass the current language to the form.
299			"""
300			kwargs = super(TranslatableModelFormMixin, self).get_form_kwargs()
301			# The TranslatableAdmin can set form.language_code, because the modeladmin always creates a fresh subclass.
302			# If that would be done here, the original globally defined form class would be updated.
303			kwargs['_current_language'] = self.get_form_language()
304			return kwargs
305
306			# Backwards compatibility
307			# Make sure overriding get_current_language() affects get_form_language() too.
308			def get_form_language(self):
309			return self.get_current_language()
310
311
312			# For the lazy ones:
313			class TranslatableCreateView(TranslatableModelFormMixin, generic.CreateView):
314			"""
315			Create view that supports translated models.
316			This is a mix of the :class:`TranslatableModelFormMixin`
317			and Django's :class:`~django.views.generic.edit.CreateView`.
318			"""
319			pass
320
321
322			class TranslatableUpdateView(TranslatableModelFormMixin, generic.UpdateView):
323			"""
324			Update view that supports translated models.
325			This is a mix of the :class:`TranslatableModelFormMixin`
326			and Django's :class:`~django.views.generic.edit.UpdateView`.
327			"""
328			pass
329
330
331			def _get_view_model(self):
332			if self.model is not None:
333			# If a model has been explicitly provided, use it
334			return self.model
335			elif hasattr(self, 'object') and self.object is not None:
336			# If this view is operating on a single object, use the class of that object
337			return self.object.__class__
338			else:
339			# Try to get a queryset and extract the model class from that
340			return self.get_queryset().model
341
342
343			# Backwards compatibility
344			TranslatableSingleObjectMixin = LanguageChoiceMixin
345

edoburu / django-parler

Pull Request — master (#135)

ViewUrlMixin.get_context_data() A

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