philo/templatetags/containers.py

   1 """
   2 The container template tags are automatically included as builtins if :mod:`philo` is an installed app.
   3
   4 """
   5
   6 from django import template
   7 from django.conf import settings
   8 from django.contrib.contenttypes.models import ContentType
   9 from django.core.exceptions import ObjectDoesNotExist
  10 from django.db.models import Q
  11 from django.utils.safestring import SafeUnicode, mark_safe
  12
  13
  14 register = template.Library()
  15
  16
  17 CONTAINER_CONTEXT_KEY = 'philo_container_context'
  18
  19
  20 class ContainerContext(object):
  21         def __init__(self, page):
  22                 self.page = page
  23
  24         def get_contentlets(self):
  25                 if not hasattr(self, '_contentlets'):
  26                         self._contentlets = dict(((c.name, c) for c in self.page.contentlets.all()))
  27                 return self._contentlets
  28
  29         def get_references(self):
  30                 if not hasattr(self, '_references'):
  31                         references = self.page.contentreferences.all()
  32                         self._references = dict((((c.name, ContentType.objects.get_for_id(c.content_type_id)), c) for c in references))
  33                 return self._references
  34
  35
  36 class ContainerNode(template.Node):
  37         def __init__(self, name, references=None, as_var=None):
  38                 self.name = name
  39                 self.as_var = as_var
  40                 self.references = references
  41
  42         def render(self, context):
  43                 container_content = self.get_container_content(context)
  44
  45                 if self.as_var:
  46                         context[self.as_var] = container_content
  47                         return ''
  48
  49                 return container_content
  50
  51         def get_container_content(self, context):
  52                 try:
  53                         container_context = context.render_context[CONTAINER_CONTEXT_KEY]
  54                 except KeyError:
  55                         try:
  56                                 page = context['page']
  57                         except KeyError:
  58                                 return settings.TEMPLATE_STRING_IF_INVALID
  59
  60                         container_context = ContainerContext(page)
  61                         context.render_context[CONTAINER_CONTEXT_KEY] = container_context
  62
  63                 if self.references:
  64                         # Then it's a content reference.
  65                         try:
  66                                 contentreference = container_context.get_references()[(self.name, self.references)]
  67                         except KeyError:
  68                                 content = ''
  69                         else:
  70                                 content = contentreference.content
  71                 else:
  72                         # Otherwise it's a contentlet.
  73                         try:
  74                                 contentlet = container_context.get_contentlets()[self.name]
  75                         except KeyError:
  76                                 content = ''
  77                         else:
  78                                 content = contentlet.content
  79                 return content
  80
  81
  82 @register.tag
  83 def container(parser, token):
  84         """
  85         If a template using this tag is used to render a :class:`.Page`, that :class:`.Page` will have associated content which can be set in the admin interface. If a content type is referenced, then a :class:`.ContentReference` object will be created; otherwise, a :class:`.Contentlet` object will be created.
  86
  87         Usage::
  88
  89                 {% container <name> [[references <app_label>.<model_name>] as <variable>] %}
  90
  91         """
  92         params = token.split_contents()
  93         if len(params) >= 2:
  94                 tag = params[0]
  95                 name = params[1].strip('"')
  96                 references = None
  97                 as_var = None
  98                 if len(params) > 2:
  99                         remaining_tokens = params[2:]
 100                         while remaining_tokens:
 101                                 option_token = remaining_tokens.pop(0)
 102                                 if option_token == 'references':
 103                                         try:
 104                                                 app_label, model = remaining_tokens.pop(0).strip('"').split('.')
 105                                                 references = ContentType.objects.get_by_natural_key(app_label, model)
 106                                         except IndexError:
 107                                                 raise template.TemplateSyntaxError('"%s" template tag option "references" requires an argument specifying a content type' % tag)
 108                                         except ValueError:
 109                                                 raise template.TemplateSyntaxError('"%s" template tag option "references" requires an argument of the form app_label.model (see django.contrib.contenttypes)' % tag)
 110                                         except ObjectDoesNotExist:
 111                                                 raise template.TemplateSyntaxError('"%s" template tag option "references" requires an argument of the form app_label.model which refers to an installed content type (see django.contrib.contenttypes)' % tag)
 112                                 elif option_token == 'as':
 113                                         try:
 114                                                 as_var = remaining_tokens.pop(0)
 115                                         except IndexError:
 116                                                 raise template.TemplateSyntaxError('"%s" template tag option "as" requires an argument specifying a variable name' % tag)
 117                         if references and not as_var:
 118                                 raise template.TemplateSyntaxError('"%s" template tags using "references" option require additional use of the "as" option specifying a variable name' % tag)
 119                 return ContainerNode(name, references, as_var)
 120
 121         else: # error
 122                 raise template.TemplateSyntaxError('"%s" template tag provided without arguments (at least one required)' % tag)