# forms.py
from .models import ServiceNote

class ButtonWidget(forms.Widget):
    template_name = 'pdf_widget.html'
    def render(self, name, value, *args, **kwargs):
        context = {
            # тут я должен передать в шаблон путь к файлу .pdf
            'url': '/'
        }
        return render_to_string(self.template_name, context)
    
class ServiceNoteForm(forms.ModelForm):
    button = forms.CharField(widget=ButtonWidget)
    class Meta:
        model = ServiceNote
        fields = '__all__'

from django.utils.safestring import mark_safe

class ServiceNoteForm(forms.ModelForm):

    button = forms.CharField()

    class Meta:
        model = ServiceNote
        fields = '__all__'


    def __init__(self, *args, **kwargs)
        super().__init__(*args, **kwargs)
        self.fields['button'].initial = mark_safe(f'<a href={self.instance.file_fild.url}>Go Button</a>')

class ButtonWidget(forms.Widget):
    template_name = 'pdf_widget.html'
    def render(self, name, value, *args, **kwargs):
        context = {
            'url': self.path_to_pdf
        }
        return render_to_string(self.template_name, context)

class ServiceNoteForm(forms.ModelForm):

    button = forms.CharField()

    class Meta:
        model = ServiceNote
        fields = '__all__'


    def __init__(self, *args, **kwargs)
        super().__init__(*args, **kwargs)
        self.fields['button'].widget = ButtonWidget()
        self.fields['button'].widget.path_to_pdf = self.instance.file_field.url