It appears that not everyone knows that in python you can create classes dynamically without metaclasses. I'll show an example of how to do it.
So we've learned how to use custom QuerySet to chain requests:
Article.objects.old().public()Now we need to make it work for related objects:
user.articles.old().public()
This is done using use_for_related_fields, but it needs a little trick. Thing is that in django related managers are initialized without arguments, and our QuerySetManager takes argument - queryset class.
objects = QuerySetManager(MyQuerySet)We have to update QuerySetManager in such a way, that will allow setting queryset as class field:
class QuerySetManager(models.Manager):
use_for_related_fields = True
queryset_class = QuerySet
def get_query_set(self):
return self.queryset_class(self.model, using=self._db)
def __getattr__(self, key):
return getattr(self.get_query_set(), key)In order to use this manager, we have to create a sublcass and set queryset_class:
class MyManager(QuerySetManager):
queryset_class = MyQuerySetIt's not fun to create such class every time. So we'll write a function that does it for us:
def queryset_manager(qs_class):
class Manager(QuerySetManager):
queryset_class = qs_class
return Manager()Now it's enough to write:
objects = queryset_manager(MyQuerySet)Subscribe for the news and updates
The article highlights common test case mistakes, offers ways to fix them, and provides practical tips to improve and optimize test cases.
Promise is a powerful tool in asynchronous programming that allows developers to call a time-consuming function and proceed with program execution without waiting for the function result.
Once we received an interesting task from a client. They needed to allow their users to upload a 3D model of the building and show it in a timelapse video from the construction site.
In this article, we have prepared a quick tutorial on how to use MongoDB in Python and listed top ORM.
Now it's time to get acquainted with Elasticsearch. This NoSQL database is used to store logs, analyze information and - most importantly - search.
Learn how to use "OR" and "AND" queries efficiently in Django without using database models Q. Enhance your query-building skills. Dive in now.