media.py

class JobMedia(db.Model):

    __tablename__ = 'jobs_media'

    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String, nullable=False, unique=True)
    job_id = db.Column(db.Integer, db.ForeignKey('jobs.id'), nullable=False, unique=True)
    job = db.relationship('Job', uselist=False,
        backref=db.backref('media', uselist=False))    

    def __init__(self, job_id):
        from app_package.helpers import db_ops
        job = db_ops.ret_val(db_ops.Job, dict(id=job_id))  # retrieves matching `job` object with `job_id` from DB
        job_title = job.title.lower()
        # turn text to a slug: split text around characters (' ._/')
        # and join again using '-' in-between words
        slug = utils.slugify(text=job_title) + '_' + str(job.id + 10000)  
        self.name = slug + '.jpg'
        self.job_id = job_id


class UserProfileMedia(db.Model):

    __tablename__ = 'users_profile_media'

    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String, nullable=False, unique=True)
    user_id = db.Column(db.Integer, db.ForeignKey('users.id'), nullable=False, unique=True)
    user = db.relationship('User', uselist=False,
        backref=db.backref('profile_media', uselist=False))    

    def __init__(self, user_id):
        from app_package.helpers import db_ops
        user = db_ops.ret_val(db_ops.User, dict(id=user_id))
        full_name = utils.get_user_full_name(user).lower() + '_' + \
            str(user_id + 10000)
        slug = utils.slugify(text=full_name)
        self.name = slug+ '.jpg'
        self.user_id = user_id