slug field on flask

Question

I want to create a slug field stored in database.

I searched and I found http://flask.pocoo.org/snippets/5/ but I'm having trouble integrating the code in my app.

This is my modele.py:

from unicodedata import normalize


def slugfy(text, encoding=None,
        permitted_chars='abcdefghijklmnopqrstuvwxyz0123456789-'):
    if isinstance(text, str):
        text = text.decode(encoding or 'ascii')
    clean_text = text.strip().replace(' ', '-').lower()
    while '--' in clean_text:
        clean_text = clean_text.replace('--', '-')
    ascii_text = normalize('NFKD', clean_text).encode('ascii', 'ignore')
    strict_text = map(lambda x: x if x in permitted_chars else '', ascii_text)
    return ''.join(strict_text)


class Chanteur(db.Model):
    id = db.Column(db.Integer, primary_key = True)
    nom = db.Column(db.String(200), index = True, unique = True)
    slug = db.Column(db.String(255))
    chanteurs = db.relationship('Chanson', backref = 'chanteur', lazy = 'dynamic')

    def __repr__(self):
        return '<Chanteur %r>' % (self.nom)

    def __setattr__(self, key, value):
        super(Chanteur, self).__setattr__(key, value)
        if key == 'nom':
            self.slug = slugfy(self.nom)


class Chanson(db.Model):
        id = db.Column(db.Integer, primary_key = True)
        titre = db.Column(db.String(255))
        chanteur_id = db.Column(db.Integer, db.ForeignKey('chanteur.id'))

        def __repr__(self):
            return '<Chanson %r>' % (self.titre)

It is not working: when I add a new objet (chanteur) the slug field is empty

Answer 1

To persist the slug in the database, I use the following approach (employing the very helpful python-slugify library):

from slugify import slugify  # among other things

class Song(db.Model):
    id = db.Column(db.Integer, primary_key = True)
    title = db.Column(db.String(255))
    slug = db.Column(db.String(255))

    def __init__(self, *args, **kwargs):
        if not 'slug' in kwargs:
            kwargs['slug'] = slugify(kwargs.get('title', ''))
        super().__init__(*args, **kwargs)