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# 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_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: str = "f",
) -> "PaginationConfig":
direction_str = parse_string(
request,
"dir",
default=default_dir,
allowed_values=[Direction.FORWARDS.value, Direction.BACKWARDS.value],
)
direction = Direction(direction_str)
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,
)
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