Define metadata for a model through an inner class “class Meta”, like this: 1 2 3 4 class Foo(models.Model): bar = models.CharField(max_length=30) class Meta: #...... Model metadata means: any data that is not a field such as ordering options, admin options, and so on. Below are all the Meta options you might use.

1. __init__(self) In a middleware class, the __init__() method is used to perform system-wide initialization settings. For performance reasons, each enabled middleware is initialized only once per server process. That is, __init__() is called only when the server process starts, and is not executed while handling an individual request. For a middleware, the usual reason to define an __init__() method is to check whether it is needed at all.

Django’s standard library lives in the django.contrib package. Each subpackage is a standalone add-on feature package. These subpackages are generally independent of one another, though some django.contrib subpackages depend on other subpackages. There is no hard requirement on the kinds of functions in django.contrib. Some of these packages ship with models (and therefore require you to install the corresponding database tables), while others consist of standalone middleware and template tags.

The team I work on is responsible for SaaS development and carries almost all of the center’s SaaS needs. Among these there are long-term maintenance projects and short-term crunch demo projects, and everyone wears several hats. Of course, the development platform is also open to other people to use, and the whole platform has hundreds if not thousands of SaaS applications.

The session mechanism for login: HTTP is a stateless protocol, and every request a browser makes is independent of the others. But not every HTTP request is unrelated to state, so the browser and the server have to jointly maintain a state — this is the session mechanism. One approach: the first time the browser sends a request to the server, the server returns a sessionID to the browser, and every subsequent request from the browser carries that sessionID to verify the same user.