Is it possible to replace a model form field in Django?

Question

PHP

there is a form, the 'sizes' field is present in the model as ManyToManyField

class AddForm(forms.ModelForm):
    quantity = forms.IntegerField(min_value=1, initial=1)

    class Meta:
        model = Product
        fields = (
            'sizes',
            'quantity',
        
        def __init__(self, *args, **kwargs):
            product_id = kwargs.pop('product_id', None)
            super(AddForm, self).__init__(*args, **kwargs)
            product = get_object_or_404(Product, id=product_id)
            self.fields['sizes'] = forms.ModelChoiceField(queryset=product.sizes.all())

how can I hide the sizes field when rendering the page and set a specific value for it,
I did this:

self.fields['sizes'] = forms.BooleanField(initial=False, widget=forms.HiddenInput)

but in this case a hidden input appears, where value="", i.e. an empty request, although I specify that initial=False
is needed in order not to show the "size" field for products where it is not needed.

Answer 1

specify the local path to the file in fopen, not url

Answer 2

you need to send the right header:
https://stackoverflow.com/questions/8485886/force-...

header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename="'.$file_name.'"');
header('Content-Transfer-Encoding: binary');
header('Expires: 0');
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header('Pragma: public');
header('Content-Length: ' . filesize($file_url)); //Absolute URL
ob_clean();
flush();
readfile($file_url); //Absolute URL
exit();

just send these headlines with a curl.