# Τεκμηρίωση του Django - 1.10.7

# Πηγαίος κώδικας για το django.shortcuts

    """
    This module collects helper functions and classes that "span" multiple levels
    of MVC. In other words, these functions/classes introduce controlled coupling
    for convenience's sake.
    """
    from django.http import (
        Http404, HttpResponse, HttpResponsePermanentRedirect, HttpResponseRedirect,
    )
    from django.template import loader
    from django.urls import NoReverseMatch, reverse
    from django.utils import six
    from django.utils.encoding import force_text
    from django.utils.functional import Promise

    def render_to_response(template_name, context=None, content_type=None, status=None, using=None):
        """
        Returns a HttpResponse whose content is filled with the result of calling
        django.template.loader.render_to_string() with the passed arguments.
        """
        content = loader.render_to_string(template_name, context, using=using)
        return HttpResponse(content, content_type, status)

    def render(request, template_name, context=None, content_type=None, status=None, using=None):
        """
        Returns a HttpResponse whose content is filled with the result of calling
        django.template.loader.render_to_string() with the passed arguments.
        """
        content = loader.render_to_string(template_name, context, request, using=using)
        return HttpResponse(content, content_type, status)

    def redirect(to, *args, **kwargs):
        """
        Returns an HttpResponseRedirect to the appropriate URL for the arguments
        passed.

        The arguments could be:

            * A model: the model's `get_absolute_url()` function will be called.

            * A view name, possibly with arguments: `urls.reverse()` will be used
              to reverse-resolve the name.

            * A URL, which will be used as-is for the redirect location.

        By default issues a temporary redirect; pass permanent=True to issue a
        permanent redirect
        """
        if kwargs.pop('permanent', False):
            redirect_class = HttpResponsePermanentRedirect
        else:
            redirect_class = HttpResponseRedirect

        return redirect_class(resolve_url(to, *args, **kwargs))

    def _get_queryset(klass):
        """
        Return a QuerySet or a Manager.
        Duck typing in action: any class with a `get()` method (for
        get_object_or_404) or a `filter()` method (for get_list_or_404) might do
        the job.
        """
        # If it is a model class or anything else with ._default_manager
        if hasattr(klass, '_default_manager'):
            return klass._default_manager.all()
        return klass

    def get_object_or_404(klass, *args, **kwargs):
        """
        Uses get() to return an object, or raises a Http404 exception if the object
        does not exist.

        klass may be a Model, Manager, or QuerySet object. All other passed
        arguments and keyword arguments are used in the get() query.

        Note: Like with get(), an MultipleObjectsReturned will be raised if more than one
        object is found.
        """
        queryset = _get_queryset(klass)
        try:
            return queryset.get(*args, **kwargs)
        except AttributeError:
            klass__name = klass.__name__ if isinstance(klass, type) else klass.__class__.__name__
            raise ValueError(
                "First argument to get_object_or_404() must be a Model, Manager, "
                "or QuerySet, not '%s'." % klass__name
            )
        except queryset.model.DoesNotExist:
            raise Http404('No %s matches the given query.' % queryset.model._meta.object_name)

    def get_list_or_404(klass, *args, **kwargs):
        """
        Uses filter() to return a list of objects, or raise a Http404 exception if
        the list is empty.

        klass may be a Model, Manager, or QuerySet object. All other passed
        arguments and keyword arguments are used in the filter() query.
        """
        queryset = _get_queryset(klass)
        try:
            obj_list = list(queryset.filter(*args, **kwargs))
        except AttributeError:
            klass__name = klass.__name__ if isinstance(klass, type) else klass.__class__.__name__
            raise ValueError(
                "First argument to get_list_or_404() must be a Model, Manager, or "
                "QuerySet, not '%s'." % klass__name
            )
        if not obj_list:
            raise Http404('No %s matches the given query.' % queryset.model._meta.object_name)
        return obj_list

    def resolve_url(to, *args, **kwargs):
        """
        Return a URL appropriate for the arguments passed.

        The arguments could be:

            * A model: the model's `get_absolute_url()` function will be called.

            * A view name, possibly with arguments: `urls.reverse()` will be used
              to reverse-resolve the name.

            * A URL, which will be returned as-is.
        """
        # If it's a model, use get_absolute_url()
        if hasattr(to, 'get_absolute_url'):
            return to.get_absolute_url()

        if isinstance(to, Promise):
            # Expand the lazy instance, as it can cause issues when it is passed
            # further to some Python functions like urlparse.
            to = force_text(to)

        if isinstance(to, six.string_types):
            # Handle relative URLs
            if to.startswith(('./', '../')):
                return to

        # Next try a reverse URL resolution.
        try:
            return reverse(to, args=args, kwargs=kwargs)
        except NoReverseMatch:
            # If this is a callable, re-raise.
            if callable(to):
                raise
            # If this doesn't "feel" like a URL, re-raise.
            if '/' not in to and '.' not in to:
                raise

        # Finally, fall back and assume it's a URL
        return to