Django form validation with authenticated user as a field - django

Question

Model:
class ProjectType(models.Model):
project_type_id = models.AutoField(primary_key=True)
name = models.CharField(max_length=45, help_text='Type of project', verbose_name='Project Type')
slug = models.SlugField(max_length=45, blank=True)
description = models.CharField(max_length=400, help_text='Description of the main purpose of the project', verbose_name='Project Type Description')
default = models.BooleanField(default=False)
owner = models.ForeignKey(User)
class Meta:
...
unique_together = (('slug', 'owner'),('name', 'owner'))
I need a form to create/update ProjectType's. Please note the owner field - it is supposed to be current logged-in user. The question is how to ensure that constraints in the unique_together are validated correctly.
I do not want to show owner field on the form - it's the current user, so it should be set automatically by the system. But no matter how I try to do this, either validation does not work, or there are other errors.
Among approaches I tried (individually or in combination):
Creating a hidden field in the related ModelField
Defining init in ProjectTypeForm (in various ways), for example:
def __init__(self, *args, **kwargs):
self.user = kwargs.pop('user', None)
super(ProjectTypeForm, self).__init__(*args, **kwargs)
self.fields['owner'].initial = self.user
Setting values in the view like:
...
if request.method == 'POST':
project_type = ProjectType(owner=request.user)
form = ProjectTypeForm(request.POST, instance=project_type, user = request.user.pk) # also tries w/o pk
...
Overriding clean() method of the form in various ways, along these lines:
def clean(self):
cleaned_data = super(ProjectTypeForm, self).clean()
slug=cleaned_data.get('slug')
owner = cleaned_data.get('owner')
if slug:
user = User.objects.get(pk=owner)
...
Many of these approaches are based on various answers found on stackoverflow.com. However, no matter what I try, I cannot find a way to accomplish what I need: (1) auto-setting of the owner field and (2) validation for uniqueness: owner/type_name and owner/type_slug. Typical errors I have is that (a) owner is not recognized as a User (it's treated as a PK), (b) incorrect validation (like lack of it or it misses the fact that it's the same record being edited, etc.), (c) owner is a required field.
For the record - if the owner is a regular field in the form, everything works as expected, but I cannot allow users to set the owner value.
Is there any, hopefully elegant, solution to this?
Thanks!

Answer 1

Exclude the owner field from your form, and save the user in your form's init method - then you can use it to validate the form, eg
class ProjectTypeForm(...):
...
def __init__(self, user, *args, **kwargs):
super(ProjectTypeForm, self).__init__(*args, **kwargs)
self.user = user
def clean(self):
user_projects = ProjectType.objects.filter(owner=self.user)
if user_projects.filter(slug=self.cleaned_data['slug']):
raise forms.ValidationError('...')
elif user_projects.filter(name=self.cleaned_data['name']):
raise forms.ValidationError('...')
else:
return self.cleaned_data
Then in your view, do something like this when creating a new ProjectType:
if request.method == 'POST':
form = ProjectTypeForm(request.user, request.POST)
if form.is_valid():
ptype = form.save(commit=False)
ptype.owner = request.user
ptype.save()
You shouldn't need that to save existing ProjectType objects though.

Answer 2

As I mentioned in my comment, one possible solution is essentially to go along with Django forms and use the owner field on the form. So, what I've done is modified init in this way:
def __init__(self, user, *args, **kwargs):
super(ProjectTypeForm, self).__init__(*args, **kwargs)
self.fields['owner'] = forms.ModelChoiceField(
label='Owner*',
queryset=User.objects.filter(username=user.username),
help_text="Project types are unique to logged-in users who are set as their owners.",
required=True,
empty_label=None)
Basically, what it does it is still using ChoiceField but sets it to one option - current user. In addition, empty_label=None ensures that there is no "empty" choice. The effect is (since username is unique) that current user name appears visible and is the only choice in the otherwise dropdown list with more choices.
In the view I follow this approach:
...
if request.method == 'POST':
project_type = ProjectType()
form = ProjectTypeForm(request.user,request.POST, instance=project_type,)
if form.is_valid():
project_type.save()
return HttpResponseRedirect(reverse('project_types'))
else:
form = ProjectTypeForm(request.user)
...
Basically, that's it - validation of unique constraints (and the whole thing) works like a charm.
Do I like this solution? No. I consider it a hack (ironically, even if it goes along with standard Django approaches). But it requires something that is totally unnecessary. One benefit of this approach is that it clearly communicates to the current user that s/he is set as the project type owner. But even with this in mind I would rather show a message (instead of a field) that Current user X will be set as the owner of the project type being created. So, if someone has a better solution, please submit it to illustrate the full power and flexibility of Django.