django 非常实用的无限级分类功能

利用model中的save方法，变相的实现递归循环，所有子分类都能在其中更新，感觉挺巧妙，之前的实现方式确实太烂了。 order的方法竟然支持1:23:2 这种方式的排序，轻松解决以前靠order_id排序的弊端。精简了代码。

其中一断代码：利用reverse 方法反推url，与无限级的order 还能用在自动生成类别链接上，便捷灵活。

def htmlpath
(
self
):

paths
=
[
]

for p
in
self.
path.
split
(
’:’
):

c
= ArticleCategory.
objects.
get
(id__exact
=p
)

url
= reverse
(
’cms.article.list’
, kwargs
=
{
’cid’:c.
id
}
)

paths.
append
(
‘<a href=”%s” target=”_blank”>%s</a>’ %
(url
, c.
name
)
)

return
” > ”.
join
(paths
)

from django.
db.
models.
signals
import pre_save

class ArticleCategory
(models.
Model
):

name
= models.
CharField
(max_length
=
50
)

parent
= models.
ForeignKey
(
’self’
, null
=
True
, blank
=
True
, related_name
=
’children’
)

path
= models.
CharField
(max_length
=
255
, null
=
True
, blank
=
True
)

def
__unicode__
(
self
):

if
self.
id
==
self.
path:

return
self.
name

else:

return
self.
node

def _node
(
self
):

indent_num
=
len
(
self.
path.
split
(
’:’
)
) –
1

indent
=
’….’ * indent_num

node
= u
’%s%s’ %
(indent
,
self.
name
)

return node

node
=
property
(_node
)

class Meta:

ordering
=
[
’path’
]

#设置在model中的用途是，是在所有节点保存时递归的循环下去，更新所有的节点的路径

def save
(
self
, * args
, ** kwargs
):

super
(ArticleCategory
,
self
).
save
(*args
, ** kwargs
)

if
self.
parent:

self.
path
=
’%s:%s’ %
(
self.
parent.
path
,
self.
id
)

else:

self.
path
=
self.
id

childrens
=
self.
children.
all
(
)

if
len
(childrens
)
>
0:

for children
in childrens:

children.
path
=
’%s:%s’ %
(
self.
path
, children.
id
)

children.
save
(
)

super
(ArticleCategory
,
self
).
save
(*args
, ** kwargs
)

#信号触发，更新

def inital_articlecategory_path
(sender
, instance
, **kwargs
):

if instance.
id:

if instance.
parent:

instance.
path
=
’%s:%s’ %
(instance.
parent.
path
, instance.
id
)

else:

instance.
path
= instance.
id

pre_save.
connect
(inital_articlecategory_path
, sender
=ArticleCategory
)

admin.py

class ArticleCategoryAdmin
(admin.
ModelAdmin
):

list_display
=
[
’treenode’
,
’patha’
,
’id’
,
]

ordering
=
[
’path’
]

def patha
(
self
, obj
):

if obj.
parent:

return u
’%s > %s’ %
(obj.
parent
, obj.
name
)

return obj.
name

patha.
short_description
=
’path’

patha.
allow_tags
=
True

def treenode
(
self
, obj
):

indent_num
=
len
(obj.
path.
split
(
’:’
)
) –
1

p
=
‘<div style=”text-indent:%spx;”>%s</div>’ %
(indent_num*
25
, obj.
name
)

return p

treenode.
short_description
=
’tree path’

treenode.
allow_tags
=
True

admin.
site.
register
(ArticleCategory
, ArticleCategoryAdmin
)

分析代码后，发现该方法可以不使用signals 来实现，在path变换后再次运行 super(ArticleCategory,self).save(*args, ** kwargs) ，这样在children中才能在新的循环save中更新path时变更正确，否则path保存时会异常。

这个是不使用signals的代码，依靠model的save的实现。

class ArticleCategory
(models.
Model
):

name
= models.
CharField
(max_length
=
50
)

parent
= models.
ForeignKey
(
’self’
, null
=
True
, blank
=
True
, related_name
=
’children’
)

path
= models.
CharField
(max_length
=
255
, null
=
True
, blank
=
True
)

def
__unicode__
(
self
):

if
self.
id
==
self.
path:

return
self.
name

else:

return
self.
node

def _node
(
self
):

indent_num
=
len
(
self.
path.
split
(
’:’
)
) –
1

indent
=
’….’ * indent_num

node
= u
’%s%s’ %
(indent
,
self.
name
)

return node

node
=
property
(_node
)

class Meta:

ordering
=
[
’path’
]

#设置在model中的用途是，是在所有节点保存时递归的循环下去，更新所有的节点的路径

def save
(
self
, * args
, ** kwargs
):

#先保存数据,如果是新添加的数据，放在第一行是用来获得id，因为id是path的重要组成

super
(ArticleCategory
,
self
).
save
(*args
, ** kwargs
)

if
self.
parent:

self.
path
=
’%s:%s’ %
(
self.
parent.
path
,
self.
id
)

else:

self.
path
=
self.
id

#更新完当前节点path后，要进行一次保存，否则在编辑类别时，子分类循环保存父类path不是最新的

super
(ArticleCategory
,
self
).
save
(*args
, ** kwargs
)

childrens
=
self.
children.
all
(
)

if
len
(childrens
)
>
0:

for children
in childrens:

children.
path
=
’%s:%s’ %
(
self.
path
, children.
id
)

children.
save
(
)

django 非常实用的无限级分类功能

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