在Python shell中添加多对多关系后使用.save（）时出错

Question

From the beginning, I created the tables in my myapp folder and from the shell ran

python manage.py sql myapp

which then produced the expected output >

BEGIN;  
CREATE TABLE "myapp_dude" (  
    "id" integer NOT NULL PRIMARY KEY,  
    "name" varchar(128) NOT NULL  
)  
;  
CREATE TABLE "myapp_group_members" (  
    "id" integer NOT NULL PRIMARY KEY,  
    "group_id" integer NOT NULL,  
    "dude_id" integer NOT NULL REFERENCES "myapp_dude" ("id"),  
    UNIQUE ("group_id", "dude_id")  
)  
;  
CREATE TABLE "myapp_group" (  
    "id" integer NOT NULL PRIMARY KEY,  
    "name" varchar(128) NOT NULL  
)  
;  
CREATE TABLE "myapp_membership" (  
    "id" integer NOT NULL PRIMARY KEY,  
    "dude_id" integer NOT NULL REFERENCES "myapp_dude" ("id"),  
    "group_id" integer NOT NULL REFERENCES "myapp_group" ("id"),  
    "date_joined" date NOT NULL,  
    "invite_reason" varchar(64) NOT NULL  
)  
;  
COMMIT;  

I then synced the databases and began running the python shell. It accepts all arguments into my tables and adds the names/groups appropriately, even the membership works, however, when I try to simply save it, I get the following error.

>>> from myapp.models import Membership, Group, Dude  
>>> from datetime import date  
>>> ringo = Dude.objects.create(name="Ringo Starr")  
>>> paul = Dude.objects.create(name="Paul McCartney")  
>>> beatles = Group.objects.create(name="The Beatles")  
>>> m1 = Membership(dude=ringo, group=beatles,  
...     date_joined=date(1962, 8, 16),  
...     invite_reason="Needed a new drummer.")  
>>> m1.save()  
Traceback (most recent call last):  
  File "<console>", line 1, in <module>  
  File "C:\Python27\lib\site-packages\django\db\models\base.py", line 460, in sa  
ve  
    self.save_base(using=using, force_insert=force_insert, force_update=force_up  
date)  
  File "C:\Python27\lib\site-packages\django\db\models\base.py", line 553, in sa  
ve_base  
    result = manager._insert(values, return_id=update_pk, using=using)  
  File "C:\Python27\lib\site-packages\django\db\models\manager.py", line 195, in  
 _insert  
    return insert_query(self.model, values, **kwargs)  
  File "C:\Python27\lib\site-packages\django\db\models\query.py", line 1436, in  
insert_query  
    return query.get_compiler(using=using).execute_sql(return_id)  
  File "C:\Python27\lib\site-packages\django\db\models\sql\compiler.py", line 79  
1, in execute_sql  
    cursor = super(SQLInsertCompiler, self).execute_sql(None)  
  File "C:\Python27\lib\site-packages\django\db\models\sql\compiler.py", line 73  
5, in execute_sql  
    cursor.execute(sql, params)  
  File "C:\Python27\lib\site-packages\django\db\backends\util.py", line 34, in e  
xecute  
    return self.cursor.execute(sql, params)  
  File "C:\Python27\lib\site-packages\django\db\backends\sqlite3\base.py", line  
234, in execute  
    return Database.Cursor.execute(self, query, params)  
DatabaseError: table myapp_membership has no column named dude_id  

I am completely thrown for a loop with this because as you can see, when the tables are created, there IS a "dude_id" column created, but at the bottom of the error message, it says that it does not have one. And also the fact that I can add to dude, and add to the membership table fine but then cannot save doesn't make much sense either. I have gone through this website, google, you name it but I have been unable to come up for a solution to this one.. Any insight will be much appreciated!!

Answer 1

Can you make sure that your database has dude_id , because I think it doesn't. This may happen because syncdb does not recreate tables if they already exist.

Answer 2

The error is pretty self explanatory. Your SQL schema differs from the one thas is defined in django. Try this

python manage.py reset myapp