Add batch support.

[aliqandil]

The title is pretty self explanatory, I'm not familiar enough with the project to create a pull request, but this is the patch I use to get this functionality:

import orjson
from bitcoinrpc import BitcoinRPC as BaseBitcoinRPC
from bitcoinrpc._exceptions import RPCError
class BitcoinRPC( BaseBitcoinRPC ):
	async def abatch( self, mp_pairs, **kwargs ):
		response = await self.client.post(
			url = self.url,
			content = orjson.dumps([
					{
						"jsonrpc": "2.0",
						"id": self._counter(),
						"method": mp.pop(0),
						"params": mp,
					}
					for mp in mp_pairs
				]
			),
			**kwargs,
		)
		response.raise_for_status()
		return [
			RPCError(content["error"]["code"], content["error"]["message"])
				if content['error'] else
			content['result']
			for content in orjson.loads(response.content)
		]
## BitcoinRPC Patch End```

[bibajz]

Hi @aliqandil , thank you for using this library as well as the issue submission!

I see your usecase and agree it would be a fine addition.

Besides a little bit of a clean-up, a thing to consider would be also the behaviour of this coroutine method when things go wrong.

Your code snippet implements the return_exceptions=True approach, meaning coroutine never raises, it treats RPCError exceptions as ordinary values and returns a list of either RPCError or the dictionary representing a valid result, ie List[Union[RPCError, dict]].

Another approach would be to raise on a first error encountered, meaning if the coroutine successfully returned, you are certain the list will not contain RPCError objects, so the signature would be List[dict].

In code, we could represent it like this:

    async def batch(
        self,
        methods_with_params: List[Tuple[str, List[JSONType]]],
        return_exceptions: bool = True,
        **kwargs: Any,
    ) -> List[Union[RPCError, BitcoinRPCResponse]]:
        request_list = [
            {
                "jsonrpc": "2.0",
                "id": self._counter(),
                "method": method,
                "params": params,
            }
            for method, params in methods_with_params
        ]
        response = await self.client.post(
            url=self.url,
            content=orjson.dumps(request_list),
            **kwargs,
        )

        # Raise an exception if return code is not in 2xx range
        # https://www.python-httpx.org/quickstart/#exceptions
        response.raise_for_status()

        content = orjson.loads(response.content)
        if return_exceptions:
            return [
                RPCError(d["error"]["code"], d["error"]["message"])
                if d["error"]
                else d["result"]
                for d in content
            ]
        else:
            # TODO: Maybe introduce an ExceptionGroup, since multiple calls may fail?
            # TODO: Would it be worth returning the results that did not fail as well?
            result = []
            for d in content:
                if d["error"]:
                    raise RPCError(d["error"]["code"], d["error"]["message"])
                else:
                    result.append(d)
            return result

---

Does it make sense? Is it okay for you to have it included in the library (with minor version bump) this or the following weekend?

As I said, the behaviour may be tricky when errors are present and I would like to have it covered by some testcases.

---

Best regards,
Libor