KrakenExchange.OnGetTickersAsync() throws Null.

[jdx-john]

https://github.com/jjxtra/ExchangeSharp/blob/4ac4ece56447cac17226811e8f9a06e5d07278f9/src/ExchangeSharp/API/Exchanges/Kraken/ExchangeKrakenAPI.cs#L564

This fails to check symbol == null which is a trivial fix but I'm not sure if this is masking a deeper problem. When I test, it fails on ETCETH. GetMarketSymbolsAsync returns ETC/ETH but GetMarketSybolsMetadataAsync has:

It seems quite an easy match; not sure why it's doing this raw string manipulation when alt fields contain the data. But I'm too tired to try a fix right now without breaking something :)

[vslee]

Since that was implemented long ago, I don't think we'll ever figure out why. Some ideas I can think of are:

• The alt field may not have existed previously
• The implementer didn't have a good view of the all of the properties and did not know about the existence of the alt field
• The alt field may not be consistent across all symbols
• some other reason not immediately apparent

Regardless, I think it would be fine to try changing to using the alt field instead

[jdx-john]

@vslee I tested changing to:

var symbol = symbols.FirstOrDefault(a => a.AltMarketSymbol.Equals(marketSymbol));
if (symbol == null)
	continue;

I now get a ticker for all 365 expected markets - that continue is never hit. I haven't checked every ticker is returning the correct value but the ones I looked at were.

It does make me nervous to silently ignore errors though, but that seems more an architecture question. I have wondered about something simple like adding IExchangeAPI.LastError which any API method can populate e.g "we expected 354 tickers but only found 349". Kind of crude but also open-ended. Someone was suggesting similarly allowing raw JSON responses to be retrieved a fe weeks back, I think?

[vslee]

It does make me nervous to silently ignore errors though, but that seems more an architecture question.

Ideally, the API would have been designed so all methods returned an enclosing object that had a Data property as well as an Error property. It's too late to change everything now though.

I have wondered about something simple like adding IExchangeAPI.LastError which any API method can populate e.g "we expected 354 tickers but only found 349". Kind of crude but also open-ended.

Yes, somewhat crude, and counts on people knowing to check that property. What do you think about just logging an message, like

Logger.Debug("we expected 354 tickers but only found 349");

Someone was suggesting similarly allowing raw JSON responses to be retrieved a fe weeks back, I think?

This was merged in #593 and already available in 0.8.1