hi Sven,

> On 13 Dec 2017, at 07:59, Ben Coman <btc@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��<sven@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