contrib/penfield/embed.py

   1 from django.contrib.contenttypes import generic
   2 from django.contrib.contenttypes.models import ContentType
   3 from django.core.exceptions import ValidationError
   4 from django.db import models
   5 from django.template import Template, loader, loader_tags
   6 import re
   7 from philo.contrib.penfield.templatetags.embed import EmbedNode
   8
   9
  10 embed_re = re.compile("{% embed (?P<app_label>\w+)\.(?P<model>\w+) (?P<pk>)\w+ %}")
  11
  12
  13 class TemplateField(models.TextField):
  14         def validate(self, value, model_instance):
  15                 """For value (a template), make sure that all included templates exist."""
  16                 super(TemplateField, self).validate(value, model_instance)
  17                 try:
  18                         self.validate_template(self.to_template(value))
  19                 except Exception, e:
  20                         raise ValidationError("Template code invalid. Error was: %s: %s" % (e.__class__.__name__, e))
  21
  22         def validate_template(self, template):
  23                 for node in template.nodelist:
  24                         if isinstance(node, loader_tags.ExtendsNode):
  25                                 extended_template = node.get_parent(Context())
  26                                 self.validate_template(extended_template)
  27                         elif isinstance(node, loader_tags.IncludeNode):
  28                                 included_template = loader.get_template(node.template_name.resolve(Context()))
  29                                 self.validate_template(extended_template)
  30
  31         def to_template(self, value):
  32                 return Template(value)
  33
  34
  35 class Embed(models.Model):
  36         embedder_content_type = models.ForeignKey(ContentType, related_name="embedder_related")
  37         embedder_object_id = models.PositiveIntegerField()
  38         embedder = generic.GenericForeignKey("embedder_content_type", "embedder_object_id")
  39
  40         embedded_content_type = models.ForeignKey(ContentType, related_name="embedded_related")
  41         embedded_object_id = models.PositiveIntegerField()
  42         embedded = generic.GenericForeignKey("embedded_content_type", "embedded_object_id")
  43
  44         def delete(self):
  45                 # Unclear whether this would be called by a cascading deletion.
  46                 super(Embed, self).delete()
  47                 # Cycle through all the fields in the embedder and remove all references to the embedded object.
  48
  49         def get_embed_tag(self):
  50                 """Convenience function to construct the embed tag that would create this instance."""
  51                 ct = self.embedded_content_type
  52                 return "{%% embed %s.%s %s %%}" % (ct.app_label, ct.model, self.embedded_object_id)
  53
  54         class Meta:
  55                 app_label = 'penfield'
  56
  57
  58 def sync_embedded_objects(model_instance, embedded_instances):
  59         # First, fetch all current embeds.
  60         model_instance_ct = ContentType.objects.get_for_model(model_instance)
  61         current_embeds = Embed.objects.filter()
  62
  63         new_embed_pks = []
  64         for embedded_instance in embedded_instances:
  65                 embedded_instance_ct = ContentType.objects.get_for_model(embedded_instance)
  66                 new_embed = Embed.objects.get_or_create(embedder_content_type=model_instance_ct, embedder_object_id=model_instance.id, embedded_content_type=embedded_instance_ct, embedded_object_id=embedded_instance.id)[0]
  67                 new_embed_pks.append(new_embed.pk)
  68
  69         # Then, delete all embed objects related to this model instance which do not relate
  70         # to one of the embedded instances.
  71         Embed.objects.filter(embedder_content_type=model_instance_ct, embedder_object_id=model_instance.id).exclude(pk__in=new_embed_pks).delete()
  72
  73
  74 class EmbedField(TemplateField):
  75         _embedded_instances = set()
  76
  77         def validate_template(self, template):
  78                 """Check to be sure that the embedded instances and templates all exist."""
  79                 for node in template.nodelist:
  80                         if isinstance(node, loader_tags.ExtendsNode):
  81                                 extended_template = node.get_parent(Context())
  82                                 self.validate_template(extended_template)
  83                         elif isinstance(node, loader_tags.IncludeNode):
  84                                 included_template = loader.get_template(node.template_name.resolve(Context()))
  85                                 self.validate_template(extended_template)
  86                         elif isinstance(node, EmbedNode):
  87                                 if node.template_name is not None:
  88                                         embedded_template = loader.get_template(node.template_name)
  89                                         self.validate_template(embedded_template)
  90                                 elif node.object_pk is not None:
  91                                         self._embedded_instances.add(node.model.objects.get(pk=node.object_pk))
  92
  93         #def to_template(self, value):
  94         #       return Template("{% load embed %}" + value)
  95
  96         def pre_save(self, model_instance, add):
  97                 if not hasattr(model_instance, '_embedded_instances'):
  98                         model_instance._embedded_instances = set()
  99                 model_instance._embedded_instances |= self._embedded_instances
 100
 101
 102 class Test(models.Model):
 103         template = TemplateField()
 104         embedder = EmbedField()
 105
 106         class Meta:
 107                 app_label = 'penfield'