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157 | """
Template tags which can do retrieval of content from any model.
"""
from django import template
from django.db.models import get_model
from template_utils.nodes import ContextUpdatingNode, GenericContentNode
class RandomObjectsNode(GenericContentNode):
"""
A subclass of ``GenericContentNode`` which overrides
``_get_query_set`` to apply random ordering.
"""
def _get_query_set(self):
return self.query_set.order_by('?')
class RetrieveObjectNode(ContextUpdatingNode):
"""
``Node`` subclass which retrieves a single object -- by
primary-key lookup -- from a given model.
Because this is a primary-key lookup, it is assumed that no other
filtering is needed; hence, the settings-based filtering performed
by ``GenericContentNode`` is not used here.
"""
def __init__(self, model, pk, varname):
self.pk = template.Variable(pk)
self.varname = varname
self.model = get_model(*model.split('.'))
if self.model is None:
raise template.TemplateSyntaxError("Generic content tag got invalid model: %s" % model)
def get_content(self, context):
return { self.varname: self.model._default_manager.get(pk=self.pk.resolve(context))}
def do_latest_object(parser, token):
"""
Retrieves the latest object from a given model, in that model's
default ordering, and stores it in a context variable.
Syntax::
{% get_latest_object [app_name].[model_name] as [varname] %}
Example::
{% get_latest_object comments.freecomment as latest_comment %}
"""
bits = token.contents.split()
if len(bits) != 4:
raise template.TemplateSyntaxError("'%s' tag takes three arguments" % bits[0])
if bits [2] != 'as':
raise template.TemplateSyntaxError("second argument to '%s' tag must be 'as'" % bits[0])
return GenericContentNode(bits[1], 1, bits[3])
def do_latest_objects(parser, token):
"""
Retrieves the latest ``num`` objects from a given model, in that
model's default ordering, and stores them in a context variable.
Syntax::
{% get_latest_objects [app_name].[model_name] [num] as [varname] %}
Example::
{% get_latest_objects comments.freecomment 5 as latest_comments %}
"""
bits = token.contents.split()
if len(bits) != 5:
raise template.TemplateSyntaxError("'%s' tag takes four arguments" % bits[0])
if bits [3] != 'as':
raise template.TemplateSyntaxError("third argument to '%s' tag must be 'as'" % bits[0])
return GenericContentNode(bits[1], bits[2], bits[4])
def do_random_object(parser, token):
"""
Retrieves a random object from a given model, and stores it in a
context variable.
Syntax::
{% get_random_object [app_name].[model_name] as [varname] %}
Example::
{% get_random_object comments.freecomment as random_comment %}
"""
bits = token.contents.split()
if len(bits) != 4:
raise template.TemplateSyntaxError("'%s' tag takes three arguments" % bits[0])
if bits [2] != 'as':
raise template.TemplateSyntaxError("second argument to '%s' tag must be 'as'" % bits[0])
return RandomObjectsNode(bits[1], 1, bits[3])
def do_random_objects(parser, token):
"""
Retrieves ``num`` random objects from a given model, and stores
them in a context variable.
Syntax::
{% get_random_objects [app_name].[model_name] [num] as [varname] %}
Example::
{% get_random_objects comments.freecomment 5 as random_comments %}
"""
bits = token.contents.split()
if len(bits) != 5:
raise template.TemplateSyntaxError("'%s' tag takes four arguments" % bits[0])
if bits [3] != 'as':
raise template.TemplateSyntaxError("third argument to '%s' tag must be 'as'" % bits[0])
return RandomObjectsNode(bits[1], bits[2], bits[4])
def do_retrieve_object(parser, token):
"""
Retrieves a specific object from a given model by primary-key
lookup, and stores it in a context variable.
Syntax::
{% retrieve_object [app_name].[model_name] [pk] as [varname] %}
Example::
{% retrieve_object flatpages.flatpage 12 as my_flat_page %}
"""
bits = token.contents.split()
if len(bits) != 5:
raise template.TemplateSyntaxError("'%s' tag takes four arguments" % bits[0])
if bits[3] != 'as':
raise template.TemplateSyntaxError("third argument to '%s' tag must be 'as'" % bits[0])
return RetrieveObjectNode(bits[1], bits[2], bits[4])
register = template.Library()
register.tag('get_latest_object', do_latest_object)
register.tag('get_latest_objects', do_latest_objects)
register.tag('get_random_object', do_random_object)
register.tag('get_random_objects', do_random_objects)
register.tag('retrieve_object', do_retrieve_object)
|
