forked-synapse/synapse/streams/config.py
Patrick Cloke 1182ae5063
Add helper to parse an enum from query args & use it. (#14956)
The `parse_enum` helper pulls an enum value from the query string
(by delegating down to the parse_string helper with values generated
from the enum).

This is used to pull out "f" and "b" in most places and then we thread
the resulting Direction enum throughout more code.
2023-02-01 21:35:24 +00:00

89 lines
2.8 KiB
Python

# Copyright 2014-2016 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import logging
from typing import Optional
import attr
from synapse.api.constants import Direction
from synapse.api.errors import SynapseError
from synapse.http.servlet import parse_enum, parse_integer, parse_string
from synapse.http.site import SynapseRequest
from synapse.storage.databases.main import DataStore
from synapse.types import StreamToken
logger = logging.getLogger(__name__)
MAX_LIMIT = 1000
@attr.s(slots=True, auto_attribs=True)
class PaginationConfig:
"""A configuration object which stores pagination parameters."""
from_token: Optional[StreamToken]
to_token: Optional[StreamToken]
direction: Direction
limit: int
@classmethod
async def from_request(
cls,
store: "DataStore",
request: SynapseRequest,
default_limit: int,
default_dir: Direction = Direction.FORWARDS,
) -> "PaginationConfig":
direction = parse_enum(request, "dir", Direction, default=default_dir)
from_tok_str = parse_string(request, "from")
to_tok_str = parse_string(request, "to")
try:
from_tok = None
if from_tok_str == "END":
from_tok = None # For backwards compat.
elif from_tok_str:
from_tok = await StreamToken.from_string(store, from_tok_str)
except Exception:
raise SynapseError(400, "'from' parameter is invalid")
try:
to_tok = None
if to_tok_str:
to_tok = await StreamToken.from_string(store, to_tok_str)
except Exception:
raise SynapseError(400, "'to' parameter is invalid")
limit = parse_integer(request, "limit", default=default_limit)
if limit < 0:
raise SynapseError(400, "Limit must be 0 or above")
limit = min(limit, MAX_LIMIT)
try:
return PaginationConfig(from_tok, to_tok, direction, limit)
except Exception:
logger.exception("Failed to create pagination config")
raise SynapseError(400, "Invalid request.")
def __repr__(self) -> str:
return "PaginationConfig(from_tok=%r, to_tok=%r, direction=%r, limit=%r)" % (
self.from_token,
self.to_token,
self.direction,
self.limit,
)