Exception reference

exception tinyrpc.exc.BadReplyError

Base class for all errors that caused processing of a reply to abort before it could be turned in a response object.

exception tinyrpc.exc.BadRequestError

Base class for all errors that caused the processing of a request to abort before a request object could be instantiated.


Create RPCErrorResponse to respond the error.

Returns:A error responce instance or None, if the protocol decides to drop the error silently.
exception tinyrpc.exc.InvalidReplyError

A reply received was malformed (i.e. violated the specification) and could not be parsed into a response.

exception tinyrpc.exc.InvalidRequestError

A request made was malformed (i.e. violated the specification) and could not be parsed.

exception tinyrpc.exc.MethodNotFoundError

The desired method was not found.

exception tinyrpc.exc.RPCError

Base class for all excetions thrown by tinyrpc.

exception tinyrpc.exc.ServerError

An internal error in the RPC system occured.

Adding custom exceptions


As per the specification you should use error codes -32000 to -32099 when adding server specific error messages. Error codes outside the range -32768 to -32000 are available for application specific error codes.

To add custom errors you need to combine an Exception subclass with the FixedErrorMessageMixin class to create your exception object which you can raise.

So a version of the reverse string example that dislikes palindromes could look like:

from tinyrpc.protocols.jsonrpc import FixedErrorMessageMixin, JSONRPCProtocol
from tinyrpc.dispatch import RPCDispatcher

dispatcher = RPCDispatcher()

class PalindromeError(FixedErrorMessageMixin, Exception):
    jsonrpc_error_code = 99
    message = "Ah, that's cheating!"

def reverse_string(s):
    r = s[::-1]
    if r == s:
        raise PalindromeError()
    return r

Error with data

The specification states that the error element of a reply may contain an optional data property. This property is now available for your use.

There are two ways that you can use to pass additional data with an Exception. It depends whether your application generates regular exceptions or exceptions derived from FixedErrorMessageMixin.

When using ordinary exceptions you normally pass a single parameter (an error message) to the Exception constructor. By passing two parameters, the second parameter is assumed to be the data element.

def fn():
    raise Exception('error message', {'msg': 'structured data', 'lst': [1, 2, 3]})

This will produce the reply message:

{   "jsonrpc": "2.0",
    "id": <some id>,
    "error": {
        "code": -32000,
        "message": "error message",
        "data": {"msg": "structured data", "lst": [1, 2, 3]}

When using FixedErrorMessageMixin based exceptions the data is passed using a keyword parameter.

class MyException(FixedErrorMessageMixin, Exception):
    jsonrcp_error_code = 99
    message = 'standard message'

def fn():
    raise MyException(data={'msg': 'structured data', 'lst': [1, 2, 3]})

This will produce the reply message:

{   "jsonrpc": "2.0",
    "id": <some id>,
    "error": {
        "code": 99,
        "message": "standard message",
        "data": {"msg": "structured data", "lst": [1, 2, 3]}