# Copyright 2021-2024 The NATS Authors
# 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.
#
from __future__ import annotations
from dataclasses import dataclass
from typing import Any, Awaitable, Callable, Dict, Optional
from nats.aio.msg import Msg
ERROR_HEADER = "Nats-Service-Error"
ERROR_CODE_HEADER = "Nats-Service-Error-Code"
class Request:
_msg: Msg
def __init__(self, msg: Msg) -> None:
self._msg = msg
self._error = None
@property
def subject(self) -> str:
"""The subject on which request was received."""
return self._msg.subject
@property
def headers(self) -> Optional[Dict[str, str]]:
"""The headers of the request."""
return self._msg.headers
@property
def data(self) -> bytes:
"""The data of the request."""
return self._msg.data
async def respond(self, data: bytes = b"", headers: Optional[Dict[str, str]] = None) -> None:
"""Send a response to the request.
:param data: The response data.
:param headers: Additional response headers.
"""
if not self._msg.reply:
raise ValueError("no reply subject set")
await self._msg._client.publish(
self._msg.reply,
data,
headers=headers,
)
async def respond_error(
self,
code: str,
description: str,
data: bytes = b"",
headers: Optional[Dict[str, str]] = None,
) -> None:
"""Send an error response to the request.
:param code: The error code describing the error.
:param description: A string describing the error which can be displayed to the client.
:param data: The error data.
:param headers: Additional response headers.
"""
if headers:
headers = headers.copy()
else:
headers = {}
headers.update(
{
ERROR_HEADER: description,
ERROR_CODE_HEADER: code,
}
)
await self.respond(data, headers=headers)
Handler = Callable[[Request], Awaitable[None]]
"""Handler is a function that processes a service request."""
@dataclass
class ServiceError(Exception):
code: str
description: str
def __repr__(self) -> str:
return f"{self.code}:{self.description}"
def to_dict(self) -> Dict[str, Any]:
return {"code": self.code, "description": self.description}
@classmethod
def from_dict(cls, data: Dict[str, Any]) -> ServiceError:
return cls(code=data.get("code", ""), description=data.get("description", ""))
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