


This article mainly introduces the relevant information of python django Transaction source code analysis. Friends who need it can refer to
python Django transaction
There is a lot of information about Django 1.6 on the Internet, but I can't find any information about 1.8. I spent a lot of effort when I wanted to use it, but it didn't work. Now there are few people who have taken note of it. Detour version: Django 1.8 Transaction official document Transaction Chinese document introduces many methods. I will not go into details one by one. Just follow the document. Below, I will only analyze the source code of the atomic method. According to the official document transaction.atomic, there are two usages: decorator and context management. Server
# atomic() 方法 # from django.db import transaction ################### # atomic() ################### def atomic(using=None, savepoint=True): # 装饰器和上下文管理器必须.()调用方法,因为真正的处理是该方法返回的实例,不是该方法本身 if callable(using): return Atomic(DEFAULT_DB_ALIAS, savepoint)(using) # Decorator: @atomic(...) or context manager: with atomic(...): ... else: return Atomic(using, savepoint) ########################################## # Atomic类 省略了非核心内容 ############################################ class Atomic(ContextDecorator): def init(self, using, savepoint): self.using = using self.savepoint = savepoint def enter(self): connection = get_connection(self.using) sid = connection.savepoint() # 进入with创建一个保存点 # .............do def exit(self, exc_type, exc_value, traceback): if connection.in_atomic_block: # do............. if sid is not None: try: connection.savepoint_commit(sid) # 提交事务 except DatabaseError: try: connection.savepoint_rollback(sid) # 捕获数据库异常回滚 connection.savepoint_commit(sid) except Error: connection.needs_rollback = True raise ## 还有一段代码是exec_type收到其他程序异常时候 全局回滚,此处省略 # do................. ############################### # ContextDecorator ################################# class ContextDecorator(object): def call(self, func): def inner(*args, **kwargs): with self: # 把函数放进self的with上下文管理器,效果with相同,只是控制细粒度不同 return func(*args, **kwargs) return inner
python MySQLdb
class Tran(): def init(self, conn=None, close=True): if conn is None: # 创建数据库链接 print 'init' self.conn = conn_tbkt() self.cur = self.conn.cursor() self.sql = [] def enter(self): # 上下文管理器返回 sql语句列表 with Tran('tbkt_pxb') as sqls: print 'enter' return self.sql # sql.append('select 1') def exit(self, exc_type, exc_val, exc_tb): print 'exit' try: print self.sql # 执行sql for s in self.sql: self.cur.execute(s) self.conn.commit() except: # 可以捕获所有异常(django事务如果中间出现程序异常终止无法回滚) try: # 回滚本身也是sql执行,也有可能失败 import traceback traceback.print_exc() print 'rollback' self.conn.rollback() except: print u'回滚失败' finally: self.cur.close() self.conn.close()
More fine-grained rollback:
# 在事务块中@atomic() 或者 with atomic(): sid = transaction.savepoint('tbkt_pxb') try: # do .......... except: transaction.savepoint_rollback(sid, 'tbkt_pxb')
Note: If there are multiple databases with routes, you need to specify the same usage as the route returns : model under math2 requires transactions. Even if ziyuan_new and default are the same library, using=ziyuan_new
ziyuan_app = ['math2', 'ziyuan'] if model._meta.app_label in ziyuan_app: return "ziyuan_new" return 'default'
must be used when calling. () method When calling the
atomic block, you must pay attention to the use of try. If the program error is manually caught, the atomic wrapper will not catch the exception, and there will be no rollback. Either the code in the try does not affect the transaction operation, or the exception is caught and raised so that atomic can roll back normally (because I did not notice this problem, I tried for several days without success, remember)
Thanks for reading, I hope this helps everyone, and thank you for your support of this site!
The above is the detailed content of Introduction to python django transaction source code analysis. For more information, please follow other related articles on the PHP Chinese website!

To maximize the efficiency of learning Python in a limited time, you can use Python's datetime, time, and schedule modules. 1. The datetime module is used to record and plan learning time. 2. The time module helps to set study and rest time. 3. The schedule module automatically arranges weekly learning tasks.

Python excels in gaming and GUI development. 1) Game development uses Pygame, providing drawing, audio and other functions, which are suitable for creating 2D games. 2) GUI development can choose Tkinter or PyQt. Tkinter is simple and easy to use, PyQt has rich functions and is suitable for professional development.

Python is suitable for data science, web development and automation tasks, while C is suitable for system programming, game development and embedded systems. Python is known for its simplicity and powerful ecosystem, while C is known for its high performance and underlying control capabilities.

You can learn basic programming concepts and skills of Python within 2 hours. 1. Learn variables and data types, 2. Master control flow (conditional statements and loops), 3. Understand the definition and use of functions, 4. Quickly get started with Python programming through simple examples and code snippets.

Python is widely used in the fields of web development, data science, machine learning, automation and scripting. 1) In web development, Django and Flask frameworks simplify the development process. 2) In the fields of data science and machine learning, NumPy, Pandas, Scikit-learn and TensorFlow libraries provide strong support. 3) In terms of automation and scripting, Python is suitable for tasks such as automated testing and system management.

You can learn the basics of Python within two hours. 1. Learn variables and data types, 2. Master control structures such as if statements and loops, 3. Understand the definition and use of functions. These will help you start writing simple Python programs.

How to teach computer novice programming basics within 10 hours? If you only have 10 hours to teach computer novice some programming knowledge, what would you choose to teach...

How to avoid being detected when using FiddlerEverywhere for man-in-the-middle readings When you use FiddlerEverywhere...


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

SublimeText3 Chinese version
Chinese version, very easy to use

MantisBT
Mantis is an easy-to-deploy web-based defect tracking tool designed to aid in product defect tracking. It requires PHP, MySQL and a web server. Check out our demo and hosting services.

PhpStorm Mac version
The latest (2018.2.1) professional PHP integrated development tool

WebStorm Mac version
Useful JavaScript development tools

ZendStudio 13.5.1 Mac
Powerful PHP integrated development environment