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                 contentlet_specs, contentreference_specs = page.template.containers
  23
  24                 contentlets = page.contentlets.filter(name__in=contentlet_specs)
  25                 self.contentlets = dict(((c.name, c) for c in contentlets))
  26
  27                 q = Q()
  28                 for name, ct in contentreference_specs.items():
  29                         q |= Q(name=name, content_type=ct)
  30                 references = page.contentreferences.filter(q)
  31                 self.references = dict(((c.name, c) for c in references))
  32
  33
  34 class ContainerNode(template.Node):
  35         def __init__(self, name, references=None, as_var=None):
  36                 self.name = name
  37                 self.as_var = as_var
  38                 self.references = references
  39
  40         def render(self, context):
  41                 content = settings.TEMPLATE_STRING_IF_INVALID
  42                 if 'page' in context:
  43                         container_content = self.get_container_content(context)
  44                 else:
  45                         container_content = None
  46
  47                 if self.as_var:
  48                         context[self.as_var] = container_content
  49                         return ''
  50
  51                 if not container_content:
  52                         return ''
  53
  54                 return container_content
  55
  56         def get_container_content(self, context):
  57                 try:
  58                         container_context = context.render_context[CONTAINER_CONTEXT_KEY]
  59                 except KeyError:
  60                         container_context = ContainerContext(context['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.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.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)