如何在视图中设置ForeignKey值

Question

My User registration form contains a ForeignKeyField and I am trying to set the value of this ForeignKeyField in the view. As can be seen in the code below, I am passing a parameter "pk" to the view and this parameter is for setting the ForeignKeyField value before the form is rendered, but this doesn't seem to work. After posting the form I get this error "(1048, "Column 'package_id' cannot be null")".

Here is my View.

def subscribe_view(request, billing_cycle, pk):
    if request.method == 'POST':
        userRegForm = CustomUserForm(request.POST)
        companyForm = CompanyProfileForm(request.POST)

        if userRegForm.is_valid() and companyForm.is_valid():
            user = userRegForm.save()
            compProfile = companyForm.save(commit=False)
            if compProfile.user_id is None:
                compProfile.user_id = user.id
            compProfile.save()

            selected_provinces = companyForm.cleaned_data['provinces']
            selected_cats = companyForm.cleaned_data['tenderCategory']
            selected_package = companyForm.cleaned_data['package']

            for province_item in selected_provinces:
                compProfile.provinces.add(province_item)

            for cat_item in selected_cats:
                compProfile.tenderCategory.add(cat_item)

            keyword_ids_str = companyForm.cleaned_data['keywordListItem']
            if keyword_ids_str is not '' or keyword_ids_str is not None:
                keyword_ids = keyword_ids_str.split(',')[:-1]
                for keyword_id in keyword_ids:
                    keywordObj = Keywords.objects.get(id=int(keyword_id.strip()))
                    compProfile.keywords.add(keywordObj)

            compProfile.package(selected_package)

            return HttpResponseRedirect('/user_account/dashboard')
        else:
            return HttpResponseRedirect(request.path)
    else:
        packageOption = Packages.objects.get(id=pk)

        if billing_cycle == '1' or billing_cycle == '0':
            b_cycle = billing_cycle
        else:
            b_cycle = '0'

        userRegForm = CustomUserForm()
        companyProfileForm = CompanyProfileForm(initial={'package': packageOption.id})
        bankingDetailsForm = BankingDetailsForm()

        #companyProfileForm.fields["package"].initial = packageOption.id

        args = {'userRegForm': userRegForm,
                'package': packageOption,
                'billing_cycle': b_cycle,
                'companyProfileForm': companyProfileForm,
                'bankingDetailsForm': bankingDetailsForm
        }
        args.update(csrf(request))
        return render(request, 'user_account/subscribe.html', args)

Here is Model:

class CompanyProfile(models.Model):
    user = models.OneToOneField(User, on_delete=models.CASCADE, primary_key=True)
    companyName = models.CharField(max_length=200, blank=False)
    companyRegNum = models.CharField(max_length=30, blank=True)
    contactNumber = models.CharField(max_length=20, blank=False)
    address = models.CharField(max_length=300, blank=True)
    areaCode = models.CharField(max_length=10, blank=False)
    deliveryEmails = models.TextField(blank=True)   #this is the list of all the people chosen to recieve daily notification.
    tenderCategory = models.ManyToManyField(category, blank=False)    #links the user to the chosen category.
    provinces = models.ManyToManyField(Province, blank=False)    #links the user to the chosen Provinces.
    package = models.ForeignKey(Packages, blank=False)       #links the user to the chosen package.
    pymntMethod = models.IntegerField(blank=True, default=3)   #this is the chosen payment method (e.g credit card=1, debit order=2 or direct debit=3)
    keywords = models.ManyToManyField(Keywords)     #links the user to the chosen keywords.
    extraKeywords = models.TextField(default='', blank=True)  #this field acts as a container of extra keywords from the user. These are keywords that we do not have in our database.
    termsAndConditions = models.BooleanField(blank=False, default=1)   #this is the T&C's field that must be agreed to by the client.
    commencementDate = models.DateTimeField(default=timezone.now, blank=True)

    def __str__(self):
        return self.companyName

Here is my form.

class CompanyProfileForm(ModelForm):
    provinces = forms.ModelMultipleChoiceField(queryset=Province.objects.all(), widget=forms.SelectMultiple(attrs={
        'id': 'provinces'
    }))

    tenderCategory = forms.ModelMultipleChoiceField(queryset=category.objects.all(), widget=forms.SelectMultiple(attrs={
        'id': 'catSelect'
    }))

    keywordListItem = forms.CharField(widget=forms.HiddenInput(attrs={
        'id': 'keywordListItem_id'
    }))

    class Meta:
        model = CompanyProfile
        exclude = (
            'user',
            'keywords',
            'commencementDate',
            'package',
        )
        fields = (
            'companyName',
            'companyRegNum',
            'contactNumber',
            'address',
            'areaCode',
            'deliveryEmails',
            'provinces',
            'tenderCategory',
            'termsAndConditions',
        )

        widgets = {
            'companyName': forms.TextInput(attrs={
                            'class': 'form-control',
                            'id': 'companyNameId',
                            'name': 'companyName',
                            'required': 'required',
                            'data-rule-required': 'true',
                            'data-msg-required': 'Please enter company name'
                        }),
            'companyRegNum': forms.TextInput(attrs={
                            'class': 'form-control',
                            'id': 'companyRegNumId',
                            'name': 'companyRegNum',
                            'required': 'required',
                            'data-rule-required': 'true',
                            'data-msg-required': 'Please enter company reg number'
                        }),
            'contactNumber': forms.TextInput(attrs={
                            'class': 'form-control input_field',
                            'id':'contactNum',
                            'name': 'contactNumber',
                            'required': 'required',
                            'data-rule-required': 'true',
                            'data-msg-required': 'Please enter contact number'
                        }),
            'address': forms.TextInput(attrs={
                            'class': 'form-control',
                            'id': 'addressId',
                            'name': 'address',
                            'required': 'required',
                            'data-rule-required': 'true',
                            'data-msg-required': 'Please enter the address'
                        }),
            'areaCode': forms.TextInput(attrs={
                            'class': 'form-control',
                            'id': 'areaCodeId',
                            'name': 'areaCode',
                            'required': 'required',
                            'data-rule-required': 'true',
                            'data-msg-required': 'Please enter the areaCode'
                        }),
            'deliveryEmails': forms.TextInput(attrs={
                            'class': 'form-control textInput',
                            'id': 'deliveryEmailId',
                            'name': 'deliveryEmails',
                            'required': 'required',
                            'data-rule-required': 'true',
                            'data-msg-required': 'Please enter the email address(s)'
                        }),

            'package': forms.HiddenInput(),
            'pymntMethod': forms.HiddenInput(attrs={
                            'id': 'pymntType',
                            'value': '3'
                        }),
            'termsAndConditions': forms.CheckboxInput(attrs={
                            'id': 'termsAndConditions'
                        })
        }

does anybody know how to fix this error?

Answer 1

There's a few things that might be contributing to what you're running into:

1. package is listed as a ForeignKey field that does not have null=True set, meaning it's a required field. As such, there needs to be a value before the model instance is saved. The reason setting a default attribute fixed that error is that you're now providing a value other than null for it. If this is a field that can allow null, update the model to include null=True , and make sure to make a migration to update your database, then try this again.

2. When updating the package , I'm noticing that the package to be assigned is being passed to it like it's a method. I'm not aware that this is valid, since attributes are usually updated by direct assignment ( compProfile.package = selected_package ).

3. When updating the attribute for a model instance ( compProfile is a model instance of CompanyProfile ), any changes to that instance's attributes are not persisted to the database unless save() is called. This means that if it were fetched from the database later, the package would not match what was assigned. Make sure that compProfile.save() is called after modifying it.