Adrià Vilanova Martínez | f19ea43 | 2024-01-23 20:20:52 +0100 | [diff] [blame^] | 1 | # Copyright 2020 The Chromium Authors |
| 2 | # Use of this source code is governed by a BSD-style license that can be |
| 3 | # found in the LICENSE file. |
Copybara | 854996b | 2021-09-07 19:36:02 +0000 | [diff] [blame] | 4 | |
| 5 | from __future__ import print_function |
| 6 | from __future__ import division |
| 7 | from __future__ import absolute_import |
| 8 | |
Adrià Vilanova Martínez | f19ea43 | 2024-01-23 20:20:52 +0100 | [diff] [blame^] | 9 | import six |
| 10 | |
Copybara | 854996b | 2021-09-07 19:36:02 +0000 | [diff] [blame] | 11 | from framework import exceptions |
| 12 | from framework import paginate |
Adrià Vilanova Martínez | f19ea43 | 2024-01-23 20:20:52 +0100 | [diff] [blame^] | 13 | from mrproto import secrets_pb2 |
Copybara | 854996b | 2021-09-07 19:36:02 +0000 | [diff] [blame] | 14 | |
| 15 | |
| 16 | def CoercePageSize(page_size, max_size, default_size=None): |
| 17 | # type: (int, int, Optional[int]) -> int |
| 18 | """Validates page_size and coerces it to max_size if needed. |
| 19 | |
| 20 | Args: |
| 21 | page_size: The page_size requested by the user. |
| 22 | max_size: the maximum page size allowed. Must be > 0. |
| 23 | Also used as default if default_size not provided |
| 24 | default_size: default size to use if page_size not provided. Must be > 0. |
| 25 | |
| 26 | Returns: |
| 27 | The appropriate page size to use for the request, based on the parameters. |
| 28 | Specifically this means |
| 29 | - page_size if not greater than max_size |
| 30 | - max_size if page_size > max_size |
| 31 | - max_size if page_size is not provided and default_size is not provided |
| 32 | - default_size if page_size is not provided |
| 33 | |
| 34 | Raises: |
| 35 | InputException: if page_size is negative. |
| 36 | """ |
| 37 | # These are programming errors. They are not user input. |
| 38 | assert max_size > 0 |
| 39 | assert default_size is None or default_size > 0 |
| 40 | |
| 41 | # Check for invalid user provided page_size. |
| 42 | if page_size and page_size < 0: |
| 43 | raise exceptions.InputException('`page_size` cannot be negative.') |
| 44 | |
| 45 | if not page_size: |
| 46 | return default_size or max_size |
| 47 | if page_size > max_size: |
| 48 | return max_size |
| 49 | return page_size |
| 50 | |
| 51 | |
| 52 | class Paginator(object): |
| 53 | """Class to manage API pagination. |
| 54 | |
| 55 | Paginator handles the pagination tasks and info of a single List or |
| 56 | Search API method implementation, given the contents of the request. |
| 57 | """ |
| 58 | |
| 59 | def __init__(self, parent=None, page_size=None, order_by=None, |
| 60 | filter_str=None, query=None, projects=None): |
| 61 | # type: (Optional[str], Optional[int], Optional[str], Optional[str], |
| 62 | # Optional[str], Optional[Collection[str]]]) -> None |
| 63 | self.request_contents = secrets_pb2.ListRequestContents( |
| 64 | parent=parent, page_size=page_size, order_by=order_by, |
| 65 | filter=filter_str, query=query, projects=projects) |
| 66 | |
| 67 | def GetStart(self, page_token): |
| 68 | # type: (Optional[str]) -> int |
| 69 | """Validates a request.page_token and returns the start index for it.""" |
| 70 | if page_token: |
| 71 | # TODO(crbug.com/monorail/6758): Proto string fields are unicode types in |
| 72 | # python 2. In python 3 these unicode strings will be represented with |
| 73 | # string types. paginate.ValidateAndParsePageToken requires a string token |
| 74 | # during validation (compare_digest()). Once we move to python 3, we can |
| 75 | # remove this string casting. |
Adrià Vilanova Martínez | f19ea43 | 2024-01-23 20:20:52 +0100 | [diff] [blame^] | 76 | token = six.ensure_binary(page_token) |
Copybara | 854996b | 2021-09-07 19:36:02 +0000 | [diff] [blame] | 77 | return paginate.ValidateAndParsePageToken(token, self.request_contents) |
| 78 | return 0 |
| 79 | |
| 80 | def GenerateNextPageToken(self, next_start): |
| 81 | # type: (Optional[int]) -> str |
| 82 | """Generates the `next_page_token` for the API response. |
| 83 | |
| 84 | Args: |
| 85 | next_start: The start index of the next page, or None if no more results. |
| 86 | |
| 87 | Returns: |
| 88 | A string clients can use to request the next page. Returns None if |
| 89 | next_start was None |
| 90 | """ |
| 91 | if next_start is None: |
| 92 | return None |
| 93 | return paginate.GeneratePageToken(self.request_contents, next_start) |