Re: charfield primary key contentype error

[Mike Dewhirst]

On 13/12/2013 9:13pm, Hervé Edorh wrote:
> Hi, I have a problem with a charfield foreign key. this my model
>
>
> class Region(models.Model):
> """ Class décrivant la table Region """
> code_region = models.CharField(max_length=15, primary_key=True)
> name = models.CharField(max_length=25,null=True,blank=True)
>
>
> class Departement(models.Model):
> """ Class décrivant la table Département """
> code_dept = models.CharField(max_length=15, primary_key=True)
> name = models.CharField(max_length=25,null=True,blank=True)
> region = models.ForeignKey(Region, null=True,blank=True)
>
>
> when i sync the database i have this error
>
>
> django.contrib.contenttypes.models.DoesNotExist: ContentType
> matching query does not exist.
>
>
> what is the meaning of this error and how can i solve it?

It is generally unconventional to have primary keys which have business
meaning. To solve the problem remove 'primary_key=True' from both
classes and rely on Django to give them their primary keys. You will
have to migrate the tables accordingly or delete them and sync again.

If necessary you can add a unique constraint to the code_region and
code_dept columns to ensure duplicates don't happen. unique=True

hth

Mike

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