def paginate(self, page=None, per_page=None, error_out=True):
"""Returns `per_page` items from page `page`. By default it will
abort with 404 if no items were found and the page was larger than
1. This behavor can be disabled by setting `error_out` to `False`.
If page or per_page are None, they will be retrieved from the
request query. If the values are not ints and ``error_out`` is
true, it will abort with 404. If there is no request or they
aren't in the query, they default to page 1 and 20
respectively.
Returns an :class:`Pagination` object.
"""
if has_request_context():
if page is None:
try:
page = int(request.args.get('page', 1))
except (TypeError, ValueError):
if error_out:
abort(404)
page = 1
if per_page is None:
try:
per_page = int(request.args.get('per_page', 20))
except (TypeError, ValueError):
if error_out:
abort(404)
per_page = 20
else:
if page is None:
page = 1
if per_page is None:
per_page = 20
if error_out and page < 1:
abort(404)
items = self.limit(per_page).offset((page - 1) * per_page).all()
if not items and page != 1 and error_out:
abort(404)
# No need to count if we're on the first page and there are fewer
# items than we expected.
if page == 1 and len(items) < per_page:
total = len(items)
else:
total = self.order_by(None).count()
return Pagination(self, page, per_page, total, items)
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