Ordering and pagination in SQL-alchemy using non-sql ranking

Unless there is a good solution, I'm going to hack together my own paginate object:

class paginate_obj:    """ Pagination dummy object. Takes a list and paginates it similar to sqlalchemy paginate() """    def __init__(self, paginatable, page, per_page):        self.has_next = (len(paginatable)/per_page) > page        self.has_prev = bool(page - 1)        self.next = page + self.has_next        self.prev = page - self.has_prev        self.items = paginatable[(page-1)*(per_page):(page)*(per_page)]

I think the only way to do ordering is to create a list of all results and sort it in python according to some lambda function:

results = my_table.query().all()results.sort(key=lamba x: distance(x.lat, x.long, user_lat, user_long)paginated_results = paginate_obj(results, 1, 10) #returns the first page of 10 elements

I think that the ordering is more important, because without it the database level pagination is completely useless. Having noted it, my answer does not cover pagination aspect at all, but I assume that even the answer provided by @mgoldwasser can be used for this.

This is what I came up with in order to be able to select some objects and preserve the order of them as per initial filter list. The code is self explanatory:

# inputpost_ids = [3, 4, 1]# create helper (temporary in-query table with two columns: post_id, sort_order)# this table looks like this:# key | sort_order#   3 |          0#   4 |          1#   1 |          2q_subq = "\nUNION ALL\n".join(    "SELECT {} AS key, {} AS sort_order".format(_id, i)    for i, _id in enumerate(post_ids))# wrap it in a `Selectable` so that we can use JOINss = (select([literal_column("key", Integer),             literal_column("sort_order", Integer)])     .select_from(text("({}) AS helper".format(text(q_subq))))     ).alias("helper")# actual query which is both the filter and sorterq = (session.query(Post)     .join(s, Post.id == s.c.key)  # INNER JOIN will filter implicitly     .order_by(s.c.sort_order)  # apply sort order     )

It works on both postgresql and sqlite.