＃在現有的對象加入日期修改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):
＃加入原數據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 <head> 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 = """<meta name="keywords" content="%s" />\n""" % escape(self.meta_keywords)
return mark_safe(meta_tag)
def get_meta_description(self):
meta_tag = ""
if self.meta_description:
meta_tag = """<meta name="description" content="%s" />\n""" % escape(self.meta_description)
return mark_safe(meta_tag)
def get_meta_author(self):
meta_tag = ""
if self.meta_author:
meta_tag = """<meta name="author" content="%s" />\n""" % escape(self.meta_author)
return mark_safe(meta_tag)
def get_meta_copyright(self):
meta_tag = ""
if self.meta_copyright:
meta_tag = """<meta name="copyright" content="%s" />\n""" % escape(self.meta_copyright)
return mark_safe(meta_tag)
def get_meta_tags(self):
return mark_safe("".join((
self.get_meta_keywords(),
self.get_meta_description(),
self.get_meta_author(),
self.get_meta_copyright(),
)))
### See recipe "Model mixin handling generic relations"
def object_relation_mixin_factory(
prefix=None,
prefix_verbose=None,
add_related_name=False,
limit_content_type_choices_to={},
limit_object_choices_to={},
is_required=False,
):
"""
returns a mixin class for generic foreign keys using
"Content type - object Id" with dynamic field names.
This function is just a class generator
Parameters:
prefix : a prefix, which is added in front of the fields
prefix_verbose : a verbose name of the prefix, used to
generate a title for the field column
of the content object in the Admin.
add_related_name : a boolean value indicating, that a
related name for the generated content
type foreign key should be added. This
value should be true, if you use more
than one ObjectRelationMixin in your model.
The model fields are created like this:
<<prefix>>_content_type : Field name for the "content type"
<<prefix>>_object_id : Field name for the "object Id"
<<prefix>>_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