How to do an upsert with SqlAlchemy?

Question

I have a record that I want to exist in the database if it is not there, and if it is there already (primary key exists) I want the fields to be updated to the current state

Answer 1

This works for me with sqlite3 and postgres. Albeit it might fail with combined primary key constraints and will most likely fail with additional unique constraints.

    try:
        t = self._meta.tables[data['table']]
    except KeyError:
        self._log.error('table "%s" unknown', data['table'])
        return

    try:
        q = insert(t, values=data['values'])
        self._log.debug(q)
        self._db.execute(q)
    except IntegrityError:
        self._log.warning('integrity error')
        where_clause = [c.__eq__(data['values'][c.name]) for c in t.c if c.primary_key]
        update_dict = {c.name: data['values'][c.name] for c in t.c if not c.primary_key}
        q = update(t, values=update_dict).where(*where_clause)
        self._log.debug(q)
        self._db.execute(q)
    except Exception as e:
        self._log.error('%s: %s', t.name, e)