爲什麼南遷移失敗？

Question

我有一個空白的MySQL數據庫，我剛剛創建。 south在我的INSTALLED_APPS。

我運行：

$ ./manage.py syncdb 
... 
Creating table some_app_table 

You just installed Django's auth system, which means you don't have any superusers defined. 
... 
Superuser created successfully. 
Installing custom SQL ... 
Installing indexes ... 
Installed 0 object(s) from 0 fixture(s) 

Synced: 
> django.contrib.auth 
> django.contrib.contenttypes 
... 

Not synced (use migrations): 
- myapp 
... 

$ ./manage.py schemamigration myapp --initial 
+ Added model myapp.Model 
... 
Created 0003_initial.py. You can now apply this migration with: ./manage.py migrate myapp 

$ ./manage.py migrate myapp 
Running migrations for myapp: 
- Migrating forwards to 0003_initial. 
> skan:0001_initial 
> skan:0002_initial 
FATAL ERROR - The following SQL query failed: CREATE TABLE `myapp_model` (`id` integer AUTO_INCREMENT NOT NULL PRIMARY KEY, `user_id` integer NULL, `name` varchar(200) NOT NULL); 
The error was: (1050, "Table 'myapp_model' already exists") 

這是怎麼回事？爲什麼不能正確初始化？

Answer 1

您已經定義了一些遷移：initial（只有在預期的情況下）纔會用於初始遷移。

你syncdb輸出說道：

Not synced (use migrations): 
- myapp 

這表明南方工作正常。但是，你這樣做：

$ ./manage.py schemamigration myapp --initial 
+ Added model myapp.Model 
... 
Created 0003_initial.py. You can now apply this migration with: ./manage.py migrate myapp 

通知的0003 -prefix：這個（最有可能）表示，目前已經有定義的遷移。這是由你的下一個命令的輸出證實：

$ ./manage.py migrate myapp 
Running migrations for myapp: 
- Migrating forwards to 0003_initial. 
> skan:0001_initial 
> skan:0002_initial 
<snip> 

換句話說，你已經有一對夫婦的initial遷移，其中至少有一個將創建一個表。您的＃3遷移再次嘗試，但失敗，因爲表格當然存在。

你需要做的只是使用initial創建你的Django應用程序。只要migrations文件夾包含名爲0001_initial.py的文件，就不需要任何初始遷移了。如果從這個角度改變你的桌子上，用auto調用它，然後遷移：

./manage.py schemamigration myapp --auto 
./manage.py migrate myapp