Getting an error while using Django Model Form in views.py

Question

In my models.py

 class Alert(models.Model):

    user = models.CharField(max_length=30, blank=True)
    a = models.IntegerField(blank=True)
    def __unicode__(self):
        return "'%s' at %s" % (self.user)

In My forms.py:

 class AlertForm(forms.ModelForm):
    class Meta:
        model=Alert
        fields = ('a','user')
        widgets = {
            'user': forms.HiddenInput()
        }

AlertCountFormset = modelformset_factory(Alert,
                                        form = AlertForm)

In my views.py:

def profile_setting(request, slug):
if request.method == 'GET':
    form = AlertForm(request.POST)
    if form.is_valid():
        alert_form = form.save(commit=False)
        alert_form.user = request.user.username
        alert_form.save() # Here i am getting the error
        return HttpResponseRedirect('/user/list')

extra_context = {
    'form': AlertForm()
}
return direct_to_template(request,'users/profile_setting.html',
                          extra_context)

I am trying to fill the Django model Form but i am getting following error where i had put the comment:

events_alertcount.a may not be NULL

What is this? Even after putting thenull=True in the field of a it shows an same error. Is that something wrong with my forms.py or models.py?

You also have a mistake in the snippet of your view code not that it matters. But you are checking the request again GET and collecting the form from POST. — Raunak Agarwal
– Raunak Agarwal, Commented Jun 30, 2012 at 20:40

Jingo · Accepted Answer · 2012-06-29 11:53:48Z

3

This is enforced on database level, too. Set your "a" column in your db to allow the field to be NULL. This should fix it. HTH.

answered Jun 29, 2012 at 11:53

Jingo

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2 Comments

Amit Pal Over a year ago

I didn't got you. Are you asking me to do this a = models.IntegerField(blank=True, null=True) ?

Jingo Over a year ago

yes, you have to declare this on 'a'. If you ran syncdb without null=True your db will have set the field to not accept NULL as value. So you have to change your db column to accept NULL as value. You can also delete the db tables and run syncdb again after you changed a to a = models.IntegerField(blank=True, null=True). But please make a backup before you delete tables when they are already filled with your data.

jagm · Accepted Answer · 2012-06-29 11:56:39Z

3

try this:

a = models.IntegerField(blank=True, null=True)

and you should call syncdb once again

answered Jun 29, 2012 at 11:56

jagm

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1 Comment

Jingo Over a year ago

syncdb does not change existing db tables!

Gezim · Accepted Answer · 2012-06-30 21:19:48Z

When defining a model field, the blank option is validation related, meaning that if you set blank to true, validation will not fail if that field is not filled in.

blank is validation-related. If a field has blank=True, validation on Django’s admin site will allow entry of an empty value. If a field has blank=False, the field will be required.

However, if validation doesn't fail and you save the model, the field will be persisted to the database. Now, a field cannot be null in the database unless you set the null option to true.

null is purely database-related, whereas blank is validation-related.

Having said that, you can fix you error by adding the null option to Alert.a:

a = models.IntegerField(blank=True, null=True)

Now, if you've already ran the syncdb command, you need to drop your tables and then rerun syncdb in order for this change to be picked up. If this database is a production database and you cannot do this, look into django-south on how you can migrate your schemas and data.

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