How to implement some sort of basic multi-tenancy? For example, to have users with separate data.

You can implement a multi-tenancy using Jam.py.

For example, if some item have a user_id field, the following code in the server module of the item will do the job:

def on_open(item, params):
    if item.session:
        user_id = item.session['user_info']['user_id']
        if user_id:
            params['__filters'].append(['user_id', item.task.consts.FILTER_EQ, user_id])

def on_apply(item, delta, params, connection):
    if item.session:
        user_id = item.session['user_info']['user_id']
        if user_id:
            for d in delta:
                if d.rec_inserted():
                    d.edit()
                    d.user_id.value = user_id
                    d.post()
                elif d.rec_modified():
                    if d.user_id.old_value != user_id:
                        raise Exception('You are not allowed to change record.')
                elif d.rec_deleted():
                    if d.user_id.old_value != user_id:
                        raise Exception('You are not allowed to delete record.')

It uses a session attribute of the item to get a unique user id and on_open and on_apply event handlers.

The on_open event handler ensures that the sql select statement that applications generates will return only records where the user_id field will be the same as the ID of the user that sends the request.

And the on_apply event handler sets the user_id to the ID of the user that appended or modified the records.

You can use a more general approach and add the following code to the server module of the task. Then a multi-tenancy will be applied to every item that have a user_id field:

def on_open(item, params):
    if item.field_by_name('user_id'):
        if item.session:
            user_id = item.session['user_info']['user_id']
            if user_id:
                params['__filters'].append(['user_id', item.task.consts.FILTER_EQ, user_id])

def on_apply(item, delta, params, connection):
    if item.field_by_name('user_id'):
        if item.session:
            user_id = item.session['user_info']['user_id']
            if user_id:
                for d in delta:
                    if d.rec_inserted():
                        d.edit()
                        d.user_id.value = user_id
                        d.post()
                    elif d.rec_modified():
                        if d.user_id.old_value != user_id:
                            raise Exception('You are not allowed to change record.')
                    elif d.rec_deleted():
                        if d.user_id.old_value != user_id:
                            raise Exception('You are not allowed to delete record.')