How does Django s Meta class work

Question

I am using Django which allows people to add extra parameters to a class by using class Meta   class FooModel models Model               class Meta                The only thing I found in Python s documentation was   class FooMetaClass type            class FooClass        metaclass     FooMetaClass   However  I don t think this is the same thing

User · Answer

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

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You are asking a question about two different things    Meta inner class in Django models   This is just a class container with some options  metadata  attached to the model  It defines such things as available permissions  associated database table name  whether the model is abstract or not  singular and plural versions of the name etc   Short explanation is here  Django docs  Models  Meta options  List of available meta options is here  Django docs  Model Meta options  For latest version of Django  Django docs  Model Meta options Metaclass in Python   The best description is here  What are metaclasses in Python

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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   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   You can explore it in Django directly too e g   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     However  in Django you are more likely to want to explore the  meta attribute which is an Options object created by the model metaclass when a model is created  That is where you ll find all of the Django class  meta  information  In Django  Meta is just used to pass information into the process of creating the  meta Options object

User · Answer

Class Meta is the place in your code logic where your model fields MEET With your form widgets  So under Class Meta   you create the link between your model  fields and the different widgets you want to have in your form

User · Answer

Django s Model class specifically handles having an attribute named Meta which is a class  It s not a general Python thing   Python metaclasses are completely different

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Inner Meta Class Document  This document of django Model metadata is    anything that   s not a field     such as ordering options  ordering   database table name  db table   or human-readable singular and plural names  verbose name and verbose name plural   None are required  and adding class Meta to a model is completely optional  https   docs djangoproject com en dev topics db models  meta-options

User · Answer

Answers that claim Django model s Meta and metaclasses are  quot completely different quot  are misleading answers  The construction of Django model class objects  that is to say the object that stands for the class definition itself  yes  classes are also objects   are indeed controlled by a metaclass called ModelBase  and you can see that code here  And one of the things that ModelBase does is to create the  meta attribute on every Django model which contains validation machinery  field details  save logic and so forth  During this operation  the stuff that is specified in the model s inner Meta class is read and used within that process  So  while yes  in a sense Meta and metaclasses are different  things   within the mechanics of Django model construction they are intimately related  understanding how they work together will deepen your insight into both at once  This might be a helpful source of information to better understand how Django models employ metaclasses  https   code djangoproject com wiki DevModelCreation And this might help too if you want to better understand how objects work in general  https   docs python org 3 reference datamodel html

[python] How does Django's Meta class work?

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