我没有使用南方。现在我想添加几列。我搞砸了吗？
(env)noah:code broinjc$ ./manage.py schemamigration reports --initial
Creating migrations directory at '/Users/broinjc/esp/code/reports/migrations'...
Creating __init__.py in '/Users/broinjc/esp/code/reports/migrations'...
+ Added model reports.Classroom
+ Added model reports.Student
+ Added model reports.SurveySet
+ Added model reports.Survey
Created 0001_initial.py. You can now apply this migration with: ./manage.py migrate reports
(env)noah:code broinjc$ ./manage.py migrate reports
Running migrations for reports:
- Migrating forwards to 0001_initial.
> reports:0001_initial
FATAL ERROR - The following SQL query failed: CREATE TABLE "reports_classroom" ("id" integer NOT NULL PRIMARY KEY, "user_id" integer NOT NULL, "added" datetime NOT NULL, "updated" datetime NOT NULL, "name" varchar(30) NOT NULL, "am_or_pm" varchar(2) NOT NULL)
The error was: table "reports_classroom" already exists
! Error found during real run of migration! Aborting.
! Since you have a database that does not support running
! schema-altering statements in transactions, we have had
! to leave it in an interim state between migrations.
! You *might* be able to recover with: = DROP TABLE "reports_classroom"; []
= DROP TABLE "reports_student"; []
= DROP TABLE "reports_surveyset"; []
= DROP TABLE "reports_survey"; []
! The South developers regret this has happened, and would
! like to gently persuade you to consider a slightly
! easier-to-deal-with DBMS (one that supports DDL transactions)
! NOTE: The error which caused the migration to fail is further up.
Error in migration: reports:0001_initial
看到这一切之后，我想，也许我需要更新我的模型（使它们与sqlite db不一致）所以我更新了它们然后运行相同的命令但是使用--auto而不是初始...
(env)noah:code broinjc$ ./manage.py schemamigration reports --auto
? The field 'SurveySet.top_num' does not have a default specified, yet is NOT NULL.
? Since you are adding this field, you MUST specify a default
? value to use for existing rows. Would you like to:
? 1. Quit now, and add a default to the field in models.py
? 2. Specify a one-off value to use for existing columns now
...所以我继续选择2，然后继续迁移......
(env)noah:code broinjc$ ./manage.py migrate reports
Running migrations for reports:
- Migrating forwards to 0002_auto__add_field_surveyset_top_num__add_field_surveyset_externalizer_ra.
> reports:0001_initial
FATAL ERROR - The following SQL query failed: CREATE TABLE "reports_classroom" ("id" integer NOT NULL PRIMARY KEY, "user_id" integer NOT NULL, "added" datetime NOT NULL, "updated" datetime NOT NULL, "name" varchar(30) NOT NULL, "am_or_pm" varchar(2) NOT NULL)
The error was: table "reports_classroom" already exists
! Error found during real run of migration! Aborting.
! Since you have a database that does not support running
! schema-altering statements in transactions, we have had
! to leave it in an interim state between migrations.
! You *might* be able to recover with: = DROP TABLE "reports_classroom"; []
= DROP TABLE "reports_student"; []
= DROP TABLE "reports_surveyset"; []
= DROP TABLE "reports_survey"; []
答案 0 :(得分：2)
我会尝试解释发生了什么，以便您更好地了解如何做自己想做的事。
在使用南方之前，您在数据库中有一些表，这些表是在您第一次运行syncdb时从模型生成的。
如果更改模型，假设您添加了一个字段“my_field”，Django在尝试读/写时会失败，因为该表不包含名为“my_field”的列。您通常必须转储整个表并使用syncdb重新创建它。我确定你不想那样做，因为你已经在DB中有了一些数据。
假设您想要在不丢失数据的情况下进行一些更改。首先，您需要"convert" your app to south。
基本上，当您运行schemamigration --initial时，South会创建一个脚本（0001_initial.py）来将模型的当前状态复制到数据库中。
如果您通过manage.py migrate reports运行该脚本，它将尝试重新创建您最初拥有的所有表，但在您的情况下，由于您的数据库已经包含这些表，因此它会尖叫您说这些表已存在：
FATAL ERROR - The following SQL query failed: CREATE TABLE "reports_classroom" ("id" integer NOT NULL PRIMARY KEY, "user_id" integer NOT NULL, "added" datetime NOT NULL, "updated" datetime NOT NULL, "name" varchar(30) NOT NULL, "am_or_pm" varchar(2) NOT NULL)
The error was: table "reports_classroom" already exists
让South相信您已经应用了该迁移的方法，您使用--fake选项。
manage.py migrate reports 0001 --fake
这就像说，转到迁移状态0001_initial（您只需要写出名称的数字部分），但实际上不应用更改。
执行此操作后，假设您向其中一个模型添加新字段“my_field_02”。和以前一样，Django引用了模型表中不存在的字段。要在不自己编写SQL的情况下创建它，请执行以下操作：
manage.py schemamigration reports --auto
这会创建一个名为0002_auto__add_my_field_02.py的新迁移，然后您需要通过manage.py migrate reports申请。您也可以说manage.py migrate reports 0002指定要转到的迁移状态，但默认情况下，South会尝试应用以下所有迁移（请记住您已经处于状态0001）。
我强烈建议您在做任何事情之前阅读South's documentation并备份您的生产数据。