CODEWITHSUNDEEP
django
User100696
User100696

Reputation: 707

Django - check if object exists

I'm trying to check if an object exists in my form but i'm getting an error.

my views:

def foo(request):
    titulo = "something"
    form = MyForm(request.POST or None)
    queryset = myModel.objects.all()
    if myModel.objects.filter(name=name).exists():
        messages.error(request, 'already exists')
    context = {
        "titulo": titulo,
        "form": form,
        "queryset": queryset,
    }
    if form.is_valid():
        instance = form.save()
        messages.success(request, 'Added')
        return redirect('/')
    return render(request, "forms7.html", context)

Basically what I'm doing is adding an user, if the user exists I want a warning saying already exists

Error:

UnboundLocalError at /model/ local variable 'name' referenced before assignment

What am I doing wrong?

Note: If I add name = 'jesus' to my code and jesus exists it works but that's not how I want.

I want to check if the name I'm entering exists show me the msg

Could someone help me? thanks.

Upvotes: 1

Views: 10899

Answers (1)

2ps
2ps

Reputation: 15926

When using forms, you get an inputted form field by calling is_valid and then accessing cleaned_data, like this:

def foo(request):
    titulo = "something"
    form = MyForm(request.POST or None)
    queryset = myModel.objects.all()
    context = {
        "titulo": titulo,
        "form": form,
        "queryset": queryset,
    }

    if form.is_valid():
        name = form.cleaned_data['name']
        if myModel.objects.filter(name=name).exists():
            messages.error(request, 'already exists')
        else:                
            instance = form.save()
            messages.success(request, 'Added')
            return redirect('/')
    return render(request, "forms7.html", context)

Ideally, you’d have a clean_name function in your form so that your view is less complicated. You can read more about creating such a method here.

For example, if you wanted to validate that the contents of a CharField called serialnumber was unique, clean_serialnumber() would be the right place to do this. You don’t need a specific field (it’s just a CharField), but you want a formfield-specific piece of validation and, possibly, cleaning/normalizing the data.

e.g., you might want something like:

class MyForm(forms.Form)
    def clean_name(self):
        name = self.cleaned_data['name']
        if myModel.objects.filter(name=name).exists():
            raise forms.ValidationError('The name [%s] already exists' % name)    
        return name

Upvotes: 5

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