JSON error, trailing characters

API Spot/Margin API
1

Hello,

I have got a problem with WS userdata stream response. I want understand the problem, but need first step.

I am acting with Testnet and all Userdata streams responses comes fine in. E.g.:
WSMessage(type=<WSMsgType.TEXT: 1>, data='{"e":"outboundAccountPosition","E":1743520170814,"u":1743520170814,"B":[{"a":"BTC","f":"1.09830000","l":"0.00000000"},{"a":"USDT","f":"1680.40258670","l":"0.00000000"}]}', extra='')

But there seems be an issue with extra=‘’
data='{"error":{"code":3,"msg":"Invalid JSON: trailing characters at line 1 column 476"}}', extra='')

I don’t know where this problem comes from. Code seems ok:

async def userdatastream(listenkey: str) -> dict:
    url = f'{base_websocket}/ws/{listenkey}'
    try:
        async with aiohttp.ClientSession() as session:
            async with session.ws_connect(url) as ws:
                async for msg in ws:
                    if msg.type == aiohttp.WSMsgType.TEXT:
                        print("userdatastream msg raw: ", msg)
                        # msg_handle()
                        if msg.data == 'close cmd':
                            await ws.close()
                            break
                        else:
                            await ws.send_str(msg.data + '/answer')
                    elif msg.type == aiohttp.WSMsgType.ERROR:
                        print('Websocket error', msg)
                        break
                    elif msg.type == aiohttp.WSMsgType.CLOSED:
                        print('Websocked closed:', msg)
    except Exception as e:
        print('Websocket error: ' ,e)
2

Hey,
The issue Invalid JSON is returned when there is a problem with the JSON data sent, not the extra field: Web Socket Streams | Binance Open Platform

Take a look at the different messages that can be sent: Web Socket Streams | Binance Open Platform

3

Thanks a lot for answering! Since yesterday I try to find out that issue…

Yes, extra='' isn’t the problem. It occours in every message. I think the source of the problem is the order request to the Endpoint.

Thanks too for the the error messages advice, but they discribed the error code with same words…

I think I have to analyse these request. But my question is: How?

My next two steps are to analyse this:

async def request_sec_trade(method: str, url:str) -> dict:
    while True:
        try:
            async with aiohttp.ClientSession() as session:
                async with getattr(session, method)(url, headers={"X-MBX-APIKEY": KEY}) as response:
                    result = await response.json()

…and to understand detailed aiohttp.

Finally, my last question is: Why the wrong order was executed?

4

In the first code snippet you shared, it looks like you’re not sending any requests. You can add the line await ws.send_json(payload) before if msg.type == aiohttp.WSMsgType.TEXT::

...
async with session.ws_connect(url) as ws:
    await ws.send_json(payload)
    async for msg in ws:
        if msg.type == aiohttp.WSMsgType.TEXT:
...

Additionally, what is the purpose of the line await ws.send_str(msg.data + '/answer')?

Since you’re sending a message that the WebSocket does not recognize, it returns the following error:
{"error":{"code":3,"msg":"Invalid JSON: trailing characters at line 1 column 23"}}.