Django form validation with authenticated user as a field

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.