Re: [Haskell-cafe] api-tools questions

Hi, I managed to my example working by using a record type to convert from/to (similar to the examples in your library Chris). Yay! I am still not sure why it didn't work when I used newtype/type to serialize to/from. Thanks for your help anyways :) k Karsten Gebbert writes:

Hi Adam,

somehow I can't get it to work according to yours and Chris' examples. I have the following test-case:

-----

stamp :: TimeStamp = basic string with inj_TimeStamp, prj_TimeStamp

test :: TestRec = record created_at :: TimeStamp

-----

$(generate tests)

-- created_at parses with: -- parseTime defaultTimeLocale "%Y-%m-%d %H:%M:%S%Q" a

type TimeStamp = Maybe UTCTime

inj_TimeStamp :: REP__TimeStamp -> ParserWithErrs TimeStamp inj_TimeStamp (REP__TimeStamp as) = return $ parseTime defaultTimeLocale "%Y-%m-%d %H:%M:%S%Q" (Text.unpack as)

prj_TimeStamp :: TimeStamp -> REP__TimeStamp prj_TimeStamp (Just mp) = REP__TimeStamp $ Text.pack $ formatTime defaultTimeLocale "%Y-%m-%d %H:%M:%S%Q" mp prj_TimeStamp Nothing = REP__TimeStamp $ Text.pack ""

$(generateAPITools tests [enumTool, jsonTool])

But, when I use it like this, I still get the format error:

λ import qualified Data.ByteString.Lazy as LBS λ import Mytest.Types λ let a = "{ \"created_at\": \"2014-09-10 14:06:48.13972\" }" :: LBS.ByteString λ decodeWithErrs a :: Either [(JSONError, Position)] TestRec Left [(BadFormat FmtUTC "UTC" "2014-09-10 14:06:48.13972",[InField "created_at"])]

It seems its not using the functions provided to parse the result at all, if I put in some bogus stuff the conversion functions and set the type of TimeStamp to Text, the created_at string appears in the output:

inj_TimeStamp :: REP__TimeStamp -> ParserWithErrs TimeStamp inj_TimeStamp (REP__TimeStamp _) = return $ Text.pack "heheheheh"

prj_TimeStamp :: TimeStamp -> REP__TimeStamp prj_TimeStamp _ = REP__TimeStamp $ Text.pack "Hohoho"

λ let a = "{ \"created_at\": \"2014-09-10 14:06:48.13972\" }" :: LBS.ByteString λ decodeWithErrs a :: Either [(JSONError, Position)] TextRec Right (TextRec {_test_created_at = "2014-09-10 14:06:48.13972"})

I'm probably missing something really simple here, but maybe you can spot it quicker than I do.. I'll investigate more when I'm back home anyways.

Thanks for any hints!

k

Adam Gundry writes:

...

Hi Karsten,

This isn't very well documented, but there is a (hidden) feature of api-tools that should do what you want. If you say something like

mt :: MyTime = basic string with inj_MyTime, prj_MyTime

then you can define your own type MyTime and give conversion functions inj_MyTime and prj_MyTime to convert back and forth from a newtype-wrapped Text. (In fact, you could probably use UTCTime as MyTime...). More precisely, api-tools will generate something like

newtype REP__MyTime = REP__MyTime Text

and you will need to implement

inj_MyTime :: REP__MyTime -> ParserWithErrs MyTime prj_MyTime :: MyTime -> REP__MyTime

I hope this helps, and further questions or documentation contributions are very welcome!

Cheers,

Adam

On 09/09/14 14:02, Karsten Gebbert wrote:

...

Hi All,

I have a question concerning the api-tools package.

Its not clear from the tests, sources or the tutorial how I can use other date/time formats that the default `utc` type can handle. I'm trying to wrap a JSON API that is not under my control, so I have to adhere to whatever I get back from it. Could anybody with experience with the package point me to some example, relevant bits in the sources or a tip how to do it?

I'm planning to create some more documentation around the package to contribute back once I figured out a few more details, because I think its quite a useful abstraction when dealing with (foreign) APIs IMO.

Thanks already for any hints,

karsten

-- Adam Gundry, Haskell Consultant Well-Typed LLP, http://www.well-typed.com/

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