Filtering Data Based On Foreign Key

[Gavin Boyle]

Hi all, 

I am having an issue dynamically populating form data based on the previous selected field. In my case I have two models one which contains different types of memberships associated to different clubs. Then I have another model which handles registrations for individual clubs. 

My problem - when the end-user is ready to sign up the form renders (I already filter out members based on the club they originally selected) but I need to filter the price based on the membership selected (foreign key) of player model.

Below is my model for the membership types:

# Model to store clubs available memberships so members can select and pay on registration page
class ClubMemberships(models.Model):

    club_id = models.ForeignKey(ClubInfo, on_delete=models.CASCADE)
    title = models.CharField(max_length=30, default='')
    price = models.DecimalField(default=0.00, max_digits=6, decimal_places=2)
    description = models.TextField()

    def __str__(self):
        return self.title

Here is the model for the registration:

# Model to store player information to be used for membership registration
class Player(models.Model):

    club_id = models.ForeignKey(ClubInfo, on_delete=models.CASCADE)
    membership_title = models.ForeignKey(ClubMemberships, on_delete=models.CASCADE)
    price = models.DecimalField(max_digits=10, decimal_places=2)
    first_name = models.CharField(max_length=20)
    last_name = models.CharField(max_length=20)
    dob = models.DateField(max_length=8)
    email = models.EmailField(max_length=50)
    phone = models.CharField(max_length=12)
    mobile = models.CharField(max_length=15)
    emergency_contact_name = models.CharField(max_length=40)
    emergency_contact_mobile = models.CharField(max_length=15)
    address1 = models.CharField(max_length=30)
    address2 = models.CharField(max_length=30, default='')
    address3 = models.CharField(max_length=30, default='')
    town = models.CharField(max_length=30)
    county = models.CharField(max_length=30)
    country = models.CharField(max_length=30)

    def __str__(self):
        return "%s %s" % (self.first_name, self.last_name)

Form for player registration:

# Form to accept details for members to register
class PlayerRegistrationForm(forms.ModelForm):

    class Meta:
        model = Player
        fields = '__all__'
        labels = {
            'dob': 'Date of Birth'
        }
        widgets = {
            'dob': forms.DateInput(attrs={'id': 'datepicker'})
        }

    def __init__(self, *args, **kwargs):
        super(PlayerRegistrationForm, self).__init__(*args, **kwargs)
        self.fields['club_id'].widget = forms.HiddenInput()

    def load_price(self, request):
        membership = request.GET.get('membership_title')
        title = ClubMemberships.objects.filter(title=membership)
        self.fields['price'].queryset = ClubMemberships.objects.filter(price=title.price)

The load_price is an example of what I am trying to accomplish but cannot get it working. I want the form to check the membership selected in the form then filter the price of that membership and display it in the form.

Here is my form in the browser:

Would really appreciate any help as I cannot incorporate PayPal until I can correctly display the price.

Thanks

Gavin 

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[Simon A]

Have you tried putting the load_price() code inside the init code? like

def __init__(self, *args, **kwargs):
        super(PlayerRegistrationForm, self).__init__(*args, **kwargs)
        self.fields['club_id'].widget = forms.HiddenInput()

        membership = request.GET.get('membership_title')