def add_share(user_from, user_to, user_checkpoint):
"""
Adds a share record to the database (if it does not exists)
"""
share = get_share_w_attr(user_from, user_to, user_checkpoint)
if share is None:
from db import db, Share
now = datetime.datetime.now()
share = Share()
share.user_from_id = user_from.id
share.user_to_id = user_to.id
share.user_checkpoint_id = user_checkpoint.id
share.timestamp = now
db.session.add(share)
db.session.commit()
#add notification
add_notification(NOTIFICATION_TYPE, user_from, user_to, share.id, user_checkpoint.id)
return share
