transactions

Table of contents Today’s content details Q query advanced operations ORM Query Optimization ORM Transaction Operations ORM Common Field Types ORM Common Fields Parameters Ajax Content-Type ajax carries file data Today’s content details Q query advanced operation from django.db.models import Qq_obj = Q() # 1. Generate q objectq_obj.cOnnector= ‘or’ # The default connection of multiple conditions is and and can be modified as orq_obj.children.append((‘pk’, 1)) # 2. Add query conditionsq_obj.children.append((‘price__gt’, 2000 )) # Support adding multiple res = models.Book.objects.filter(q_obj) # Query supports directly filling in q objectsprint(res) ORM query optimization 1.ORM queries are lazy queries by default2.ORM queries come with Pagination processing3.only and defer ”’data object + data corresponding to the specified field”’ # res = models.Book.objects.only(‘title’, ‘price’) # print(res) # queryset [data object, data object] # for obj in res: # print(obj.title) # Click on the field filled in the brackets without entering the SQL query # print(obj.price) # print(obj.publish_time) # You can click on the fields not in the brackets to get the data but you can use SQL query res = models.Book.objects.defer(‘title ‘, ‘price’) # print(res) # queryset [data object, data object] for obj in res: # print(obj.title) # Click on the field filled in the brackets…