Django - legacy db and problems with 'id' field

Question

I'm integrating a MySQL database from a php app into a new Django project. Inspectdb worked well, I just had to change a couple of fields to ForeignKeys and now all the reading and editing current data is working great.

The problem is when I try to create a new entry, I get the error "Field 'id' doesn't have a default value". The traceback starts from the form.save() call and the exception is coming from the MySQL cursor. In most cases the column is named id but in one case it is a named value:

class ModelOne(models.Model): #normal "id" named pk 
    id = models.AutoField(primary_key=True, db_column='id', default=None)
    other_fields = ...

class ModelTwo(models.Model): #specific pk
    named_pk = models.AutoField(primary_key=True, db_column='named_pk',
                                default=None)
    other_fields = ...

For ModelTwo, when I POST a valid form, I get the error, but then if I go back to my data list, the new item shows up! And after I checked the latest id values in the shell, I can see that they are incrementing correctly.

But for ModelOne (with just id), the error still shows up, and the pk become 2147483647 (the max) and subsequent saves fail because of duplicate ids. (the next highest pk is only 62158)

What do I need to do to get these id fields working correctly?

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update: Still no luck fixing this. Thinking about dumping the data and importing it into fresh, Django-built tables. Still looking for a solution to this problem.

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update2: Info from db shell

ModelOne:

+-------------+--------------+-------+------+---------+-----------------+
| Field       | Type         | Null  | Key  | Default | Extra           |
| id          | int(11)      | NO    | PRI  | NULL    | auto_increment  |

ModelTwo:

+-------------+--------------+-------+------+---------+-----------------+
| Field       | Type         | Null  | Key  | Default | Extra           |
| named_pk    | int(11)      | NO    | PRI  | NULL    | auto_increment  |

Answer 1

I met the same issue after some complex South migration. We wanted to avoid to reload the database (dump/import), luckily it will help other peoples who fall on this post after searching for the same issue.

We found a solution which solve this problem without the need of exporting and importing the database.

For a table named auth_user, the following MySQL command will fixe the above error message:

ALTER TABLE auth_user MODIFY `id` INT(11) NOT NULL AUTO_INCREMENT;

original solution from :

http://webit.ca/2012/01/field-id-doesnt-have-a-default-value/

Answer 2

It makes sense to define pk for ModelTwo (as your are already doing) because your pk has different name 'named_pk'. However, no need to explicitly define 'id' as your pk for ModelOne. Django will create id column by default. So do not define the id column at all for ModelOne.

UPDATE: remove "default=None" from the model and default NULL from the database for ModelTwo for named_pk