blob: 16e66faf23e65e99ae884db6f733d8404b4a2f32 [file] [log] [blame]
# Copyright 2020 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file.
from __future__ import print_function
from __future__ import division
from __future__ import absolute_import
from framework import exceptions
from framework import paginate
from proto import secrets_pb2
def CoercePageSize(page_size, max_size, default_size=None):
# type: (int, int, Optional[int]) -> int
"""Validates page_size and coerces it to max_size if needed.
Args:
page_size: The page_size requested by the user.
max_size: the maximum page size allowed. Must be > 0.
Also used as default if default_size not provided
default_size: default size to use if page_size not provided. Must be > 0.
Returns:
The appropriate page size to use for the request, based on the parameters.
Specifically this means
- page_size if not greater than max_size
- max_size if page_size > max_size
- max_size if page_size is not provided and default_size is not provided
- default_size if page_size is not provided
Raises:
InputException: if page_size is negative.
"""
# These are programming errors. They are not user input.
assert max_size > 0
assert default_size is None or default_size > 0
# Check for invalid user provided page_size.
if page_size and page_size < 0:
raise exceptions.InputException('`page_size` cannot be negative.')
if not page_size:
return default_size or max_size
if page_size > max_size:
return max_size
return page_size
class Paginator(object):
"""Class to manage API pagination.
Paginator handles the pagination tasks and info of a single List or
Search API method implementation, given the contents of the request.
"""
def __init__(self, parent=None, page_size=None, order_by=None,
filter_str=None, query=None, projects=None):
# type: (Optional[str], Optional[int], Optional[str], Optional[str],
# Optional[str], Optional[Collection[str]]]) -> None
self.request_contents = secrets_pb2.ListRequestContents(
parent=parent, page_size=page_size, order_by=order_by,
filter=filter_str, query=query, projects=projects)
def GetStart(self, page_token):
# type: (Optional[str]) -> int
"""Validates a request.page_token and returns the start index for it."""
if page_token:
# TODO(crbug.com/monorail/6758): Proto string fields are unicode types in
# python 2. In python 3 these unicode strings will be represented with
# string types. paginate.ValidateAndParsePageToken requires a string token
# during validation (compare_digest()). Once we move to python 3, we can
# remove this string casting.
token = str(page_token)
return paginate.ValidateAndParsePageToken(token, self.request_contents)
return 0
def GenerateNextPageToken(self, next_start):
# type: (Optional[int]) -> str
"""Generates the `next_page_token` for the API response.
Args:
next_start: The start index of the next page, or None if no more results.
Returns:
A string clients can use to request the next page. Returns None if
next_start was None
"""
if next_start is None:
return None
return paginate.GeneratePageToken(self.request_contents, next_start)