To make your core a little bit more reliable you should not catch the general error but a NeoJSONParseError. And you need to guard the dictionary access. There is no guarantee you get something back that inlcudes key success and message.
Norbert > Am 13.12.2017 um 09:54 schrieb Ben Coman <b...@openinworld.com>: > > hi Sven, > >> > On 13 Dec 2017, at 07:59, Ben Coman <b...@openinworld.com> wrote: >> > >> > >> > With... >> > Object subclass: #BittrexResponse >> > instanceVariableNames: 'success message result' >> > classVariableNames: '' >> > package: 'Bittrex' >> > >> > Object subclass: #BittrexMarketSummary >> > instanceVariableNames: 'MarketName High Low Volume Last >> > BaseVolume TimeStamp Bid Ask OpenBuyOrders >> > OpenSellOrders PrevDay Created DisplayMarketName' >> > classVariableNames: '' >> > package: 'Bittrex' >> > >> > this code works great when the response holds good data... >> > ZnClient new >> > url: >> > 'https://bittrex.com/api/v1.1/public/getmarketSummary?market=BTC-LTC'; >> > enforceHttpSuccess: true; >> > accept: ZnMimeType applicationJson; >> > contentReader: [ :entity | |reader| >> > reader := (NeoJSONReader on: entity readStream). >> > reader for: BittrexResponse do: [:m| >> > m mapInstVar: #success. >> > m mapInstVar: #message. >> > (m mapInstVar: #result) valueSchema: #ResultArray]. >> > reader for: #ResultArray customDo: [ :mapping | >> > mapping listOfElementSchema: BittrexMarketSummary ]. >> > reader mapInstVarsFor: BittrexMarketSummary. >> > reader nextAs: BittrexResponse ]; >> > get. >> > >> > i.e. a raw response looking like this.... >> > (ZnClient new >> > url: >> > 'https://bittrex.com/api/v1.1/public/getmarketsummary?market=BTC-LTC'; >> > get) inspect. >> > ==> >> > "'{""success"":true,""message"":"",""result"":[{""MarketName"":""BTC-LTC"",""High"":0.01982450,""Low"":0.01285257,""Volume"":1436429.81313360,""Last"":0.01842000,""BaseVolume"":24841.17217724,""TimeStamp"":""2017-12-13T05:56:25.937"",""Bid"":0.01840001,""Ask"":0.01842000,""OpenBuyOrders"":10140,""OpenSellOrders"":6306,""PrevDay"":0.01439800,""Created"":""2014-02-13T00:00:00""}]}'" >> > >> > >> > But for bad response looking like this... >> > (ZnClient new >> > url: >> > 'https://bittrex.com/api/v1.1/public/getmarketsummary?market=INVALID'; >> > get) inspect. >> > ==> {"success":false,"message":"INVALID_MARKET","result":null} >> > >> > the JSON handling code fails deep in the call stack with an error >> > "NeoJSONParseError: [ expected" >> > which is not so friendly for users of the Bittrex library. >> > >> > What are the different/recommended approaches with Zinc >> > for catching JSON errors such that I can pass "message" >> > as a higher level Error up the stack to the Bittrex user. >> > >> > cheers -ben > > >> On 13 December 2017 at 15:37, Sven Van Caekenberghe <s...@stfx.eu> wrote: >> BTW, this is no about Zinc, but about NeoJSON. >> >> This is what I meant with variability that is hard to capture with a simple >> static type schema. >> >> I have no time to try myself right now, but a custom mapping for ivar result >> (as in a block) might be able to see the difference and act accordingly. > > > okay. So I played around tracing this through the debugger and for anyone > else > with a similar need later, I ended up with the following... > > response := (ZnClient new > url: 'https://bittrex.com/api/v1.1/public/getticker?market=INVALID'; > enforceHttpSuccess: true; > accept: ZnMimeType applicationJson; > contentReader: > [ :entity | > [ |reader| > reader := (NeoJSONReader on: entity readStream). > reader for: BittrexResponse do: > [:m| > m mapInstVar: #success. > m mapInstVar: #message. > (m mapInstVar: #result) valueSchema: > BittrexTicker > ]. > reader mapInstVarsFor: BittrexTicker. > reader nextAs: BittrexResponse > ] on: Error do: > [ :err | |json| > json := NeoJSONReader fromString: entity > contents. > (json at: 'success') > ifFalse: [ self error: (json at: > 'message') ] > ifTrue: [ self error: 'UKNOWN ERROR' ] > ] > ]) get. > > > for which I get a nice pre-debug window titled "Error: INVALID_MARKET" > > cheers -ben >
