Re: How to access the value of a field that failed validation

If you print:

dir(form_instance)

You'll get the methods available to the form. From memory, amongst
these you will find "data" and "initial", I think that "data"
contains the information submitted in the form action. So, to show that:

print(form.data)


-- Clive

On 2 Jan 2023, at 00:12, Noel Duffy wrote:

> I'm new to Django, though not to programming. I'm using Django
> 4.1.4 on AlmaLinux 9.
>
> My question is this. Is it possible to access a ModelForm field's
> value if that form field failed validation?
>
> I'm writing a small ticketing system for a helpdesk to handle spam
> reports. Users submit spam messages which the system will then
> process. I'm using a ModelForm, and the database schema specifies
> that the spam message is unique. That is, each spam message can be
> reported only once, so there's just one ticket but possibly many
> different actions taken depending on what's in the spam.
>
> This is the model:
>
> class AbuseReport(models.Model):
> report_date = models.DateTimeField(auto_now_add=True)
> report_subject = models.CharField(max_length=255)
> report_msgid = models.CharField(max_length=255, unique = True)
> report_spam_text = models.TextField(unique = True)
> def __str__(self):
> return report_subject
>
> class Meta:
> ordering = ['-report_date']
>
> Now, the problem is that a spam message will fail form validation
> in the form.is_valid call if the spam message fails the "unique"
> constraint. Why is this a problem? Because I want to get my hands
> on the spam message if it's already in the DB so that instead of
> just re-showing my form with an error message saying the spam
> already exists, I want to redirect to the existing ticket. But so
> far I've not been able to figure out how to do this, and when I
> dump the contents of the form in debugging, the spam message just
> isn't there.
>
> I should add that the ModelForm only creates a field for the
> report_spam_text field. I.e,
>
> class AbuseReportForm(ModelForm):
> def __init__(self, *args, **kwargs):
> super(ModelForm, self).__init__(*args, **kwargs)
>
> def clean(self):
> [...]
>
> class Meta:
> model = AbuseReport
> fields = ['report_spam_text']
> widgets = {'report_spam_text':
> Textarea(attrs={
> 'rows': 20,
> 'class':'textarea',
> 'placeholder':'Paste spam with full headers
> here..'
> }),}
>
>
> This is what my view looks like (stripped down for simplicity):
>
> def spamsubmit(request):
> # if this is a POST request we need to process the form data
> if request.method == 'POST':
> # create a form instance and populate it with data from the
> request:
> form = AbuseReportForm(request.POST)
> # check whether it's valid:
> if form.is_valid():
> # process the data in form.cleaned_data as required
> [.....]
> else:
> ## show the form again with errors displayed
> ## if spam already exists this is what gets run.
> return render(request, 'abuse/spam_form.html',
> {'form':form})
>
> As I understand it, fields aren't bound to data until is_valid is
> called, and if is_valid fails then only fields that didn't fail
> validity go into cleaned_data. But it seems everything else is
> lost. But I'm not 100% sure about this and this is why I'm asking.
>
>
>
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>

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