django中如何实现model对象加入装饰器-创新互联
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＃在现有的对象加入日期修改Mixin
class Person(CreationModificationDateMixin):
多出字段：
| created | datetime(6) | NO | | NULL | | | modified | datetime(6) | YES | | NULL | | |
＃加入url MinIn
class Person(UrlMixin):
＃加入原数据MInxIn
class Person(MetaTagsMixin):
多出字段：
| meta_keywords | varchar(255) | NO | | NULL | | | meta_description | varchar(255) | NO | | NULL | | | meta_author | varchar(255) | NO | | NULL | | | meta_copyright | varchar(255) | NO | | NULL | | |
# -*- coding: UTF-8 -*-
from __future__ import unicode_literals
import urlparse
from django.conf import settings
from django.utils.timezone import now as timezone_now
from django.utils.safestring import mark_safe
from django.template.defaultfilters import escape
from django.db import models
from django.utils.translation import ugettext_lazy as _
from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes.fields import GenericForeignKey
from django.core.exceptions import FieldError
### See recipe "Model mixin with URL-related methods"
class UrlMixin(models.Model):
"""
A replacement for get_absolute_url()
Models extending this mixin should have either get_url or get_url_path implemented.
http://code.djangoproject.com/wiki/ReplacingGetAbsoluteUrl
"""
class Meta:
abstract = True
def get_url(self):
if hasattr(self.get_url_path, "dont_recurse"):
raise NotImplementedError
try:
path = self.get_url_path()
except NotImplementedError:
raise
website_url = getattr(settings, "DEFAULT_WEBSITE_URL", "http://127.0.0.1:8000")
return website_url + path
get_url.dont_recurse = True
def get_url_path(self):
if hasattr(self.get_url, "dont_recurse"):
raise NotImplementedError
try:
url = self.get_url()
except NotImplementedError:
raise
bits = urlparse.urlparse(url)
return urlparse.urlunparse(("", "") + bits[2:])
get_url_path.dont_recurse = True
def get_absolute_url(self):
return self.get_url_path()
### See recipe "Model mixin handling creation and modification dates"
class CreationModificationDateMixin(models.Model):
"""
Abstract base class with a creation and modification date and time
"""
created = models.DateTimeField(
_("creation date and time"),
editable=False,
)
modified = models.DateTimeField(
_("modification date and time"),
null=True,
editable=False,
)
def save(self, *args, **kwargs):
if not self.pk:
self.created = timezone_now()
else:
# To ensure that we have a creation data always, we add this one
if not self.created:
self.created = timezone_now()
self.modified = timezone_now()
super(CreationModificationDateMixin, self).save(*args, **kwargs)
save.alters_data = True
class Meta:
abstract = True
### See recipe "Model mixin taking care of meta tags"
class MetaTagsMixin(models.Model):
"""
Abstract base class for meta tags in the section
"""
meta_keywords = models.CharField(
_("Keywords"),
max_length=255,
blank=True,
help_text=_("Separate keywords by comma."),
)
meta_description = models.CharField(
_("Description"),
max_length=255,
blank=True,
)
meta_author = models.CharField(
_("Author"),
max_length=255,
blank=True,
)
meta_copyright = models.CharField(
_("Copyright"),
max_length=255,
blank=True,
)
class Meta:
abstract = True
def get_meta_keywords(self):
meta_tag = ""
if self.meta_keywords:
meta_tag = """>_content_type : Field name for the "content type"
<>_object_id : Field name for the "object Id"
<>_content_object : Field name for the "content object"
"""
p = ""
if prefix:
p = "%s_" % prefix
content_type_field = "%scontent_type" % p
object_id_field = "%sobject_id" % p
content_object_field = "%scontent_object" % p
class TheClass(models.Model):
class Meta:
abstract = True
if add_related_name:
if not prefix:
raise FieldError("if add_related_name is set to True, a prefix must be given")
related_name = prefix
else:
related_name = None
optional = not is_required
ct_verbose_name = (
_("%s's type (model)") % prefix_verbose
if prefix_verbose
else _("Related object's type (model)")
)
content_type = models.ForeignKey(
ContentType,
verbose_name=ct_verbose_name,
related_name=related_name,
blank=optional,
null=optional,
help_text=_("Please select the type (model) for the relation, you want to build."),
limit_choices_to=limit_content_type_choices_to,
)
fk_verbose_name = (prefix_verbose or _("Related object"))
object_id = models.CharField(
fk_verbose_name,
blank=optional,
null=False,
help_text=_("Please enter the ID of the related object."),
max_length=255,
default="", # for south migrations
)
object_id.limit_choices_to = limit_object_choices_to
# can be retrieved by MyModel._meta.get_field("object_id").limit_choices_to
content_object = GenericForeignKey(
ct_field=content_type_field,
fk_field=object_id_field,
)
TheClass.add_to_class(content_type_field, content_type)
TheClass.add_to_class(object_id_field, object_id)
TheClass.add_to_class(content_object_field, content_object)
return TheClass 关于“django中如何实现model对象加入装饰器”这篇文章就分享到这里了，希望以上内容可以对大家有一定的帮助，使各位可以学到更多知识，如果觉得文章不错，请把它分享出去让更多的人看到。
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