The group_by method is used in Django, and django uses group_by

The group_by method is used in Django, and django uses group_by

This example describes how to use group_by in Django. Share it with you for your reference. The specific analysis is as follows:

How to Use the group_by statement in Django? I have found a lot of information and have not seen it. Here are two ways to share with you:

First, create a simple model.

Class Book (models. model): name = models. charField (u 'title ', max_length = 255, db_index = True) author = models. charField (u'author ', max_length = 255) remark = models. charField (u'note', max_length = 255) pub_date = models. dateTimeField (u'posting time', auto_now_add = True)

Method 1:

Book_list = Book. objects. all () book_list.query.group_by = ['author']

Method 2:

Query = Book. objects. all (). query. group_by = ['autor'] book_list = QuerySet (query = query, model = Book)

However, I found a small problem in practical application:

If the author field has a null value, an error will be reported in the following way. If the author field has a null value, an error will be reported in the second way.

I hope this article will help you with Python programming.