__str__ returned non-string (type tuple)

Question

I have a form that keeps throwing me an error in django, Ive tried searching online tried str() on my models but wouldnt work at all. Googled a couple of times tried a couple different methods but none worked still get the same django error page everytime i click the link to the form.

TypeError: __str__ returned non-string (type tuple)

my model

# Injury Parameters -> SOI Level 2 #
####################################
class SourceOfInjuryLevel2(models.Model):
    creator = models.ForeignKey('auth.User')
    id = models.AutoField(primary_key=True)
    soi_l1 = models.CharField(max_length=80)
    soi_l2 = models.CharField(max_length=80)
    status = models.CharField(max_length=8)
    created_date = models.DateTimeField(default=timezone.now)
    modified_date = models.DateTimeField(blank=True, null=True)
    modified_by = models.CharField(max_length=60, blank=True, null=True)

    def create(self):
        self.save()

    def __str__(self):
        return self.soi_l1, self.soi_l2, self.status

my form

# Soure of Injury Level 2 #
###########################
class SourceOfInjuryLevel2Form(forms.ModelForm):
    options = (('Enabled', 'Enabled',), ('Disabled', 'Disabled'))
    soi_l1 = forms.ModelChoiceField(
            queryset=SourceOfInjuryLevel1.objects.filter(status='Enabled'),
            widget=forms.Select(attrs={'class': 'form-control'})
            )
    soi_l2 = forms.CharField(
            widget=forms.TextInput(attrs={'class': 'form-control'})
            )
    status = forms.CharField(
            widget=forms.Select(
                attrs={'class': 'form-control'},
                choices=options
                )
            )

    class Meta:
        model = SourceOfInjuryLevel2
        fields = ('soi_l1', 'soi_l2', 'status')

My Views

# New Source of Injury Level 2 #
################################
def new_source_of_injury_level2(request):
    form = SourceOfInjuryLevel2Form()
    if request.method == "POST":
        form = SourceOfInjuryLevel2Form(request.POST)
        if form.is_valid():
            source_of_injury_level2 = form.save(commit=False)
            source_of_injury_level2.creator = request.user
            source_of_injury_level2.created_date = timezone.now()
            source_of_injury_level2.save()
            messages.success(request, 'Object Has Been Created')
            return redirect(injury_parameters)
        else:
            messages.error(request, 'Object Has Not Been Created')
    else:
        form = SourceOfInjuryLevel2Form()
    return render(request,
                  'process_injury_management/source_of_injury_level2.html',
                  {'form': form,
                   'title': 'New Source of Injury Level 2'})

Answer 1

Those commas aren't actually doing what you think they do. The commas make your return value a tuple instead of a string which a __str__ method is supposed to return.

You can instead do:

def __str__(self):
    return '%s %s %s'%(self.soi_l1, self.soi_l2, self.status)

Or use the new-style formatting:

def __str__(self):
    return '{} {} {}'.format(self.soi_l1, self.soi_l2, self.status)

Answer 2

The error is in your model:

class SourceOfInjuryLevel2(models.Model):

    ...

    def __str__(self):
        return self.soi_l1, self.soi_l2, self.status

I guess you were confused because the Python 2 print statement looks like it turns tuples into strings, but that's not actually how the print statement works - it's a confusing detail that was changed in Python 3.

Try this instead:

def __str__(self):
    template = '{0.soi_l1} {0.soi_l2} {0.status}'
    return template.format(self)