IntegrityError --- NOT NULL constraint failed: books_book.publication_date

[Sami Razi]

  
 i'm learning django using djangobook, in chapter 6, i'm having this error:

      IntegrityError at /admin/books/book/add/

      NOT NULL constraint failed: books_book.publication_date


it seems i should set null=True for  publication_date field. but i did it already, this is my models.py:

         
from django.db import models

class Publisher(models.Model):
    name = models.CharField(max_length=30)
    address = models.CharField(max_length=50)
    city = models.CharField(max_length=60)
    state_province = models.CharField(max_length=30)
    country = models.CharField(max_length=50)
    website = models.URLField()
  
    def __unicode__(self):
        return self.name
  
class Author(models.Model):
    first_name = models.CharField(max_length=30)
    last_name = models.CharField(max_length=40)
    email = models.EmailField(blank=True, verbose_name='e-mail')
 
    def __unicode__(self):
        return u'%s %s' % (self.first_name, self.last_name)
 
class Book(models.Model):
    title = models.CharField(max_length=100)
    authors = models.ManyToManyField(Author)
    publisher = models.ForeignKey(Publisher)
   publication_date = models.DateField(blank=True, null=True)
  
    def __unicode__(self):
        return self.title
      

what am i doing wrong?
i googled the error message but didn't find a related answer.
thank you for your help.

[Sam Walters]

Did you perhaps change the schema of the database after you had created it.

Eg: added null=True as a constraint after creating the table?

If so check the db sheme using:
python manage.py sqlall <appname>

It sounds simple enough. You will have to go into the db shell and update your schema manually.

using

python manage.py dbshell

If you're developing something where the schema is always getting modified and you dont want to manually update table constraints

look into

django south addon.

hope this helps

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