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, contentlets, references):
  22                 self.contentlets = dict(((c.name, c) for c in contentlets))
  23                 self.references = dict((((c.name, ContentType.objects.get_for_id(c.content_type_id)), c) for c in references))
  24
  25
  26 class ContainerNode(template.Node):
  27         def __init__(self, name, references=None, as_var=None):
  28                 self.name = name
  29                 self.as_var = as_var
  30                 self.references = references
  31
  32         def render(self, context):
  33                 container_content = self.get_container_content(context)
  34
  35                 if self.as_var:
  36                         context[self.as_var] = container_content
  37                         return ''
  38
  39                 return container_content
  40
  41         def get_container_content(self, context):
  42                 try:
  43                         container_context = context.render_context[CONTAINER_CONTEXT_KEY]
  44                 except KeyError:
  45                         try:
  46                                 page = context['page']
  47                         except KeyError:
  48                                 return settings.TEMPLATE_STRING_IF_INVALID
  49
  50                         contentlet_specs, contentreference_specs = page.template.containers
  51                         contentlets = page.contentlets.filter(name__in=contentlet_specs)
  52                         q = Q()
  53                         for name, ct in contentreference_specs.items():
  54                                 q |= Q(name=name, content_type=ct)
  55                         references = page.contentreferences.filter(q)
  56
  57                         container_context = ContainerContext(contentlets, references)
  58                         context.render_context[CONTAINER_CONTEXT_KEY] = container_context
  59
  60                 if self.references:
  61                         # Then it's a content reference.
  62                         try:
  63                                 contentreference = container_context.references[(self.name, self.references)]
  64                         except KeyError:
  65                                 content = ''
  66                         else:
  67                                 content = contentreference.content
  68                 else:
  69                         # Otherwise it's a contentlet.
  70                         try:
  71                                 contentlet = container_context.contentlets[self.name]
  72                         except KeyError:
  73                                 content = ''
  74                         else:
  75                                 content = contentlet.content
  76                 return content
  77
  78
  79 @register.tag
  80 def container(parser, token):
  81         """
  82         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.
  83
  84         Usage::
  85
  86                 {% container <name> [[references <app_label>.<model_name>] as <variable>] %}
  87
  88         """
  89         params = token.split_contents()
  90         if len(params) >= 2:
  91                 tag = params[0]
  92                 name = params[1].strip('"')
  93                 references = None
  94                 as_var = None
  95                 if len(params) > 2:
  96                         remaining_tokens = params[2:]
  97                         while remaining_tokens:
  98                                 option_token = remaining_tokens.pop(0)
  99                                 if option_token == 'references':
 100                                         try:
 101                                                 app_label, model = remaining_tokens.pop(0).strip('"').split('.')
 102                                                 references = ContentType.objects.get_by_natural_key(app_label, model)
 103                                         except IndexError:
 104                                                 raise template.TemplateSyntaxError('"%s" template tag option "references" requires an argument specifying a content type' % tag)
 105                                         except ValueError:
 106                                                 raise template.TemplateSyntaxError('"%s" template tag option "references" requires an argument of the form app_label.model (see django.contrib.contenttypes)' % tag)
 107                                         except ObjectDoesNotExist:
 108                                                 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)
 109                                 elif option_token == 'as':
 110                                         try:
 111                                                 as_var = remaining_tokens.pop(0)
 112                                         except IndexError:
 113                                                 raise template.TemplateSyntaxError('"%s" template tag option "as" requires an argument specifying a variable name' % tag)
 114                         if references and not as_var:
 115                                 raise template.TemplateSyntaxError('"%s" template tags using "references" option require additional use of the "as" option specifying a variable name' % tag)
 116                 return ContainerNode(name, references, as_var)
 117
 118         else: # error
 119                 raise template.TemplateSyntaxError('"%s" template tag provided without arguments (at least one required)' % tag)