scratch-site/scratch_show/forms.py

import re

from django import forms
from . import models


SCRATCH_ID_REGEX = re.compile(r'https://scratch\.mit\.edu/projects/([0-9]+)')

def get_scratch_id_from_url(url):
    match = SCRATCH_ID_REGEX.search(url)
    return int(match.group(1))


class ScratchURLField(forms.URLField):
    def clean(self, value):
        url = super().clean(value)
        scratch_id = get_scratch_id_from_url(url)
        return scratch_id


class ScratchProjectAddForm(forms.ModelForm):
    url = ScratchURLField(label='Lien Scratch du projet (URL)')

    class Meta:
        fields = ('name', 'author_name', 'url')
        model = models.ScratchProject