How can I dynamically define forms.IntegerField's min_value parameter?

Question

I am working with Django and its Forms classes.

I have created a Form with a single forms.IntegerField and I want to define its min_value parameter dynamically:

class BiddingForm(forms.Form):
    bidding_form = forms.IntegerField(min_value=1, help_text="€", label="Bid")

Right now, it is statically set to 1. I have tried to overwrite the __init__() function and pass in a min_value there. But since bidding_form is a class variable, I cannot use the resulting instance variable min_value on it:

class BiddingForm(forms.Form):
    min_value = 1

    def __init__(self, min_value):
        super().__init__()
        self.min_value = min_value

    bidding_form = forms.IntegerField(min_value=min_value, help_text="€", label="Bid")

As of my understanding, above class creates an instance variable min_value inside of __init__() which just shadows the class variable min_value and it ultimately results in min_value being 1 in the bidding_form's declaration.
Since I have little understanding of Python and Django, I have not yet found a solution to this.
So, how can I dynamically define forms.IntegerField's min_value parameter?

Davis Herring · Accepted Answer · 2023-09-17 17:45:12Z

2

You override the min_value of the field:

from django.core import validators MinValueValidator

class BiddingForm(forms.Form):
    bidding_form = forms.IntegerField(help_text='€', label='Bid')

    def __init__(self, *args, min_value=None, **kwargs):
        super().__init__(*args, **kwargs)
        bidding_form = self.fields['bidding_form']
        bidding_form.min_value = min_value
        if min_value is not None:
            bidding_form.validators.append(MinValueValidator(min_value))
            bidding_form.widget.attrs['min'] = min_value

edited Sep 17, 2023 at 17:45

Davis Herring

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answered Jan 9, 2021 at 17:00

willeM_ Van Onsem

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3 Comments

René Jörg Spies Over a year ago

Thank you for the fast answer. Unfortunately, I have encoutered 2 problems. When I pass self to super().__init() I am getting 'BiddingForm' object has no attribute 'get'. When I leave it, the site is shown but the min_value is ignored and my IntegerField can now have any value. How is that?

IgorArnaut Jul 4 at 23:45

Can I do it the same to a ModelForm?

willeM_ Van Onsem Jul 5 at 4:23

Yes. transforming the BiddingForm to a ModelForm normally should do the trick.

kızagan · Accepted Answer · 2023-09-11 06:32:56Z

0

Correct way is:

class BidForm(forms.Form):
    bid = forms.IntegerField()

    def __init__(self, min_bid_value=0, *args, **kwargs):
        super(BidForm, self).__init__(*args, **kwargs)
        self.fields['bid'].widget.attrs['min'] = min_bid_value

You can call it like :

BidForm(min_bid_value=145)

and form won't let user enter number less than 145.

answered Sep 11, 2023 at 6:32

kızagan

1

Comments

HONCHO · Accepted Answer · 2021-01-09 17:03:38Z

-1

i dont think so but you can do check the length of the specified field before you check if form.is_valid():. like: if len(form.cleaned_data['field']) < min:

answered Jan 9, 2021 at 17:03

HONCHO

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