The Django database complements the business

When you write data to a database, you inadvertently write incomplete data, which we call dirty data. Transaction management (transaction) can prevent this from happening. Transaction management Once a write exception is detected, a rollback operation is performed, either writing the full data or not writing it. The use of transactions in Django is simple:

1. New project transaction, create app App01, edit models Create two tables and perform a database migration as follows:

 from Import Models class UserInfo (models. Model):    = models. Charfield (max_length=32)    = models. Emailfield (max_length=64)class  Dept (models. Model):    = models. Charfield (MAX_LENGTH=32)

2. Define the route:

 from Import URL  from Import  = [    url (r'^test/$', Views.test),]

3. Define the test view function;

 fromDjango.shortcutsImportRender, HttpResponse from.ImportModelsdefTest (Request):Try:         fromDjango.dbImportTransaction#Import TransactionsWith transaction.atomic (): User_obj= Models. UserInfo.objects.create (username='Lena', email='[email protected]') Dept_obj= Models. Dept.objects.create (title='IT')    exceptException as E:returnHttpResponse ('error happened, DB rollback')    returnHttpResponse ('OK')

Description

1. The above combines the created user_obj and dept_obj recorded behavior into an indivisible atomic operation that performs a rollback operation if any exception occurs in the database operation performed within the atom.
2. Things are checked for exception rollback, but not fault-tolerant, errors are thrown, so here is an exception catch.
3. Normal access http://127.0.0.1:8000/test/ , will get an OK response, if we manually dept_obj = models.Dept.objects.create(title=‘IT‘) change to title=‘IT‘ name=‘IT‘ , manually caused the exception, then the thing will trigger rollback, write user_obj will also be revoked. This allows you to view database validation.

　　Note : Transactions require support from the database engine, such as the InnoDB engine.

The Django database complements the business