blocks|key|585573|text|Django的Model类专门处理一个名为Meta的属性，它是一个类。这不是一般的Python的事情。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|585574|Python元类则完全不同。|585575|entityMap^0|7|5|L|4|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]|$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|O|8|@]|D|@]|E|$]]|$1|H|3|-4|5|6|7|P|8|@]|D|@]|E|$]]]|I|$]]

Django's <code>Model</code> class specifically handles having an attribute named <code>Meta</code> which is a class. It's not a general Python thing.

Python metaclasses are completely different.

blocks|key|369966|text|扩展Tadeck的Django回答，在Django中使用'class+Meta:‘也是普通的Python。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|369967|内部类是一个方便的命名空间，用于在类实例之间共享数据(因此得名为Meta，表示“元数据”，但您可以随心所欲地叫它)。虽然在Django中它通常是只读的配置内容，但没有什么可以阻止您更改它：|369968|In+[1]:+class+Foo(object):
+++...:+++++class+Meta:
+++...:+++++++++metaVal+=+1
+++...:+++++++++
In+[2]:+f1+=+Foo()
In+[3]:+f2+=+Foo()
In+[4]:+f1.Meta.metaVal
Out[4]:+1
In+[5]:+f2.Meta.metaVal+=+2
In+[6]:+f1.Meta.metaVal
Out[6]:+2
In+[7]:+Foo.Meta.metaVal
Out[7]:+2|code-block|syntax|javascript|369969|你也可以直接在Django中探索它，例如：|369970|In+[1]:+from+django.contrib.auth.models+import+User
In+[2]:+User.Meta
Out[2]:+django.contrib.auth.models.Meta
In+[3]:+User.Meta.__dict__
Out[3]:+
{'__doc__':+None,
+'__module__':+'django.contrib.auth.models',
+'abstract':+False,
+'verbose_name':+<django.utils.functional.__proxy__+at+0x26a6610>,
+'verbose_name_plural':+<django.utils.functional.__proxy__+at+0x26a6650>}|369971|然而，在Django中，您更可能想要探索_meta属性，它是在创建模型时由模型metaclass创建的Options对象。在那里你可以找到所有Django类的“元”信息。在Django中，Meta只是用于将信息传递到创建_meta+Options对象的过程中。|offset|length|style|CODE|369972|entityMap^0|0|0|0|0|0|K|5|13|9|1F|7|2M|4|32|5|38|7|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|W|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|X|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|Y|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|Z|8|@$O|10|P|11|Q|R]|$O|12|P|13|Q|R]|$O|14|P|15|Q|R]|$O|16|P|17|Q|R]|$O|18|P|19|Q|R]|$O|1A|P|1B|Q|R]]|9|@]|A|$]]|$1|S|3|-4|5|6|7|1C|8|@]|9|@]|A|$]]]|T|$]]

Extending on Tadeck's Django answer above, the use of 'class Meta:' in Django is just normal Python too.

The internal class is a convenient namespace for shared data among the class instances (hence the name Meta for 'metadata' but you can call it anything you like). While in Django it's generally read-only configuration stuff, there is nothing to stop you changing it:

<pre><code>In [1]: class Foo(object):
 ...: class Meta:
 ...: metaVal = 1
 ...: 
In [2]: f1 = Foo()
In [3]: f2 = Foo()
In [4]: f1.Meta.metaVal
Out[4]: 1
In [5]: f2.Meta.metaVal = 2
In [6]: f1.Meta.metaVal
Out[6]: 2
In [7]: Foo.Meta.metaVal
Out[7]: 2
</code></pre>

You can explore it in Django directly too e.g:

<pre><code>In [1]: from django.contrib.auth.models import User
In [2]: User.Meta
Out[2]: django.contrib.auth.models.Meta
In [3]: User.Meta.__dict__
Out[3]: 
{'__doc__': None,
 '__module__': 'django.contrib.auth.models',
 'abstract': False,
 'verbose_name': &lt;django.utils.functional.__proxy__ at 0x26a6610&gt;,
 'verbose_name_plural': &lt;django.utils.functional.__proxy__ at 0x26a6650&gt;}
</code></pre>

However, in Django you are more likely to want to explore the <code>_meta</code> attribute which is an <code>Options</code> object created by the model <code>metaclass</code> when a model is created. That is where you'll find all of the Django class 'meta' information. In Django, <code>Meta</code> is just used to pass information into the process of creating the <code>_meta</code> <code>Options</code> object.

blocks|key|370070|text|内部Meta类文档：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|370071|这个django模型元数据文档是“任何不是字段的内容”，比如排序选项(ordering),+database+table+name+(db_table),+or+human-readable+singular+and+plural+names+(verbose_name+and+verbose_name_plural)。这不是必需的，向模型添加Meta类完全是可选的。https://docs.djangoproject.com/en/dev/topics/db/models/#meta-options|offset|length|style|CODE|370072|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.djangoproject.com/en/dev/topics/db/models/#meta-options^0|0|2|6|Y|3I|55|1W|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Q|8|@$D|R|E|S|F|G]|$D|T|E|U|F|G]]|9|@$D|V|E|W|1|X]]|A|$]]|$1|H|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|I|$J|$5|K|L|M|A|$N|O]]]]

Inner Meta Class Document:
This document of <code>django</code>
Model metadata is “anything that’s not a field”, such as ordering options <code>(ordering), database table name (db_table), or human-readable singular and plural names (verbose_name and verbose_name_plural)</code>. None are required, and adding class Meta to a model is completely optional.
<a href="https://docs.djangoproject.com/en/dev/topics/db/models/#meta-options" rel="nofollow noreferrer">https://docs.djangoproject.com/en/dev/topics/db/models/#meta-options</a>

blocks|key|585767|text|在Django中，它充当配置类，并将配置数据保存在一个位置！！|type|unstyled|depth|inlineStyleRanges|entityRanges|data|585768|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

In Django, it acts as a configuration class and keeps the configuration data in one place!!

I am using Django which allows people to add extra parameters to a class by using <code>class Meta</code>.

<pre><code>class FooModel(models.Model):
 ...
 class Meta:
 ...
</code></pre>

The only thing I found in Python's documentation was:

<pre><code>class FooMetaClass(type):
 ...

class FooClass:
 __metaclass__ = FooMetaClass
</code></pre>

However, I don't think this is the same thing.

How does Django's nested Meta class work?

Django

Python

我使用的是Django，它允许人们通过使用class Meta向类添加额外的参数。class FooModel(models.Model):    ...    class Meta:        ...我在Python文档中找到的唯一内容是：class FooMetaClass(type):    ...class...

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