Edit: While this post is a duplicate of Django's ModelForm unique_together validation, the accepted answer here of removing the 'exclude' from the ModelForm is a much cleaner solution than the accepted answer in the other question.
This is a follow-up to this question.
If I don't explicitly check the unique_together constraint in the clean_title() function, django throws an exception:
IntegrityError at /journal/journal/4
duplicate key value violates unique constraint "journal_journal_owner_id_key"
Request Method: POST
Request URL: http://localhost:8000/journal/journal/4
Exception Type: IntegrityError
Exception Value: duplicate key value violates unique constraint "journal_journal_owner_id_key"
Exception Location: /Library/Python/2.6/site-packages/django/db/backends/util.py in execute, line 19
However I was under the impression that Django would enforce this constraint nicely by raising a ValidationError, not with an exception I need to catch.
Below is my code with an additional clean_title() method I use as a work-around. But I want to know what I'm doing wrong such that django is not enforcing the constraint in the expected manner.
Thanks.
Model code:
class Journal (models.Model):
owner = models.ForeignKey(User, related_name='journals')
title = models.CharField(null=False, max_length=256)
published = models.BooleanField(default=False)
class Meta:
unique_together = ("owner", "title")
def __unicode__(self):
return self.title
Form code:
class JournalForm (ModelForm):
class Meta:
model = models.Journal
exclude = ('owner',)
html_input = forms.CharField(label=u'Journal Content:', widget=TinyMCE(attrs={'cols':'85', 'rows':'40'}, ), )
def clean_title(self):
title = self.cleaned_data['title']
if self.instance.id:
if models.Journal.objects.filter(owner=self.instance.owner, title=title).exclude(id=self.instance.id).count() > 0:
raise forms.ValidationError(u'You already have a Journal with that title. Please change your title so it is unique.')
else:
if models.Journal.objects.filter(owner=self.instance.owner, title=title).count() > 0:
raise forms.ValidationError(u'You already have a Journal with that title. Please change your title so it is unique.')
return title
View Code:
def journal (request, id=''):
if not request.user.is_active:
return _handle_login(request)
owner = request.user
try:
if request.method == 'GET':
if '' == id:
form = forms.JournalForm(instance=owner)
return shortcuts.render_to_response('journal/Journal.html', { 'form':form, })
journal = models.Journal.objects.get(id=id)
if request.user.id != journal.owner.id:
return http.HttpResponseForbidden('<h1>Access denied</h1>')
data = {
'title' : journal.title,
'html_input' : _journal_fields_to_HTML(journal.id),
'published' : journal.published
}
form = forms.JournalForm(data, instance=journal)
return shortcuts.render_to_response('journal/Journal.html', { 'form':form, })
elif request.method == 'POST':
if LOGIN_FORM_KEY in request.POST:
return _handle_login(request)
else:
if '' == id:
journal = models.Journal()
journal.owner = owner
else:
journal = models.Journal.objects.get(id=id)
form = forms.JournalForm(data=request.POST, instance=journal)
if form.is_valid():
journal.owner = owner
journal.title = form.cleaned_data['title']
journal.published = form.cleaned_data['published']
journal.save()
if _HTML_to_journal_fields(journal, form.cleaned_data['html_input']):
html_memo = "Save successful."
else:
html_memo = "Unable to save Journal."
return shortcuts.render_to_response('journal/Journal.html', { 'form':form, 'saved':html_memo})
else:
return shortcuts.render_to_response('journal/Journal.html', { 'form':form })
return http.HttpResponseNotAllowed(['GET', 'POST'])
except models.Journal.DoesNotExist:
return http.HttpResponseNotFound('<h1>Requested journal not found</h1>')
UPDATE WORKING CODE: Thanks to Daniel Roseman.
Model code stays the same as above.
Form code - remove exclude statement and clean_title function:
class JournalForm (ModelForm):
class Meta:
model = models.Journal
html_input = forms.CharField(label=u'Journal Content:', widget=TinyMCE(attrs={'cols':'85', 'rows':'40'},),)
View Code - add custom uniqueness error message:
def journal (request, id=''):
if not request.user.is_active:
return _handle_login(request)
try:
if '' != id:
journal = models.Journal.objects.get(id=id)
if request.user.id != journal.owner.id:
return http.HttpResponseForbidden('<h1>Access denied</h1>')
if request.method == 'GET':
if '' == id:
form = forms.JournalForm()
else:
form = forms.JournalForm(initial={'html_input':_journal_fields_to_HTML(journal.id)},instance=journal)
return shortcuts.render_to_response('journal/Journal.html', { 'form':form, })
elif request.method == 'POST':
if LOGIN_FORM_KEY in request.POST:
return _handle_login(request)
data = request.POST.copy()
data['owner'] = request.user.id
if '' == id:
form = forms.JournalForm(data)
else:
form = forms.JournalForm(data, instance=journal)
if form.is_valid():
journal = form.save()
if _HTML_to_journal_fields(journal, form.cleaned_data['html_input']):
html_memo = "Save successful."
else:
html_memo = "Unable to save Journal."
return shortcuts.render_to_response('journal/Journal.html', { 'form':form, 'saved':html_memo})
else:
if form.unique_error_message:
err_message = u'You already have a Lab Journal with that title. Please change your title so it is unique.'
else:
err_message = form.errors
return shortcuts.render_to_response('journal/Journal.html', { 'form':form, 'error_message':err_message})
return http.HttpResponseNotAllowed(['GET', 'POST'])
except models.Journal.DoesNotExist:
return http.HttpResponseNotFound('<h1>Requested journal not found</h1>')
