3158b55 · typeable/http-api-data

git.iko.soy/typeable/http-api-data

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Add notes that Generic-based implementation only works for records

3158b55Nickolay Kudasov10 years ago

src/Web/Internal/FormUrlEncoded.hs+22−2

compare with master

unifiedsplit

@@ -211,7 +211,8 @@ instance IsList Form where

211-- instance 'ToForm' Person

212-- @

213--

214+-- The default implementation of 'toForm' is 'genericToForm'.

214−-- The default implementation will use 'toQueryParam' for each field's value.

215+-- It only works for records and it will use 'toQueryParam' for each field's value.

215class ToForm a where

216class ToForm a where

216 -- | Convert a value into 'Form'.

217 -- | Convert a value into 'Form'.

217 toForm :: a -> Form

218 toForm :: a -> Form

@@ -243,6 +244,15 @@ data Proxy3 a b c = Proxy3

243

244

244-- | A 'Generic'-based implementation of 'toForm'.

245-- | A 'Generic'-based implementation of 'toForm'.

245-- This is used as a default implementation in 'ToForm'.

246-- This is used as a default implementation in 'ToForm'.

247+--

248+-- Note that this only works for records (i.e. product data types with named fields):

249+--

250+-- @

251+-- data Person = Person

252+-- { name :: String

253+-- , age :: Int

254+-- } deriving ('Generic')

255+-- @

246genericToForm :: (Generic a, GToForm (Rep a)) => a -> Form

256genericToForm :: (Generic a, GToForm (Rep a)) => a -> Form

247genericToForm = gToForm . from

257genericToForm = gToForm . from

248

258

@@ -296,7 +306,8 @@ instance (Selector s, ToHttpApiData c) => GToForm (M1 S s (K1 i c)) where

296-- instance 'FromForm' Person

306-- instance 'FromForm' Person

297-- @

307-- @

298--

308--

309+-- The default implementation of 'fromForm' is 'genericFromForm'.

299−-- The default implementation will use 'parseQueryParam' for each field's value.

310+-- It only works for records and it will use 'parseQueryParam' for each field's value.

300class FromForm a where

311class FromForm a where

301 -- | Parse 'Form' into a value.

312 -- | Parse 'Form' into a value.

302 fromForm :: Form -> Either Text a

313 fromForm :: Form -> Either Text a

@@ -329,6 +340,15 @@ toEntriesByKey = traverse parseGroup . HashMap.toList . unForm

329

340

330-- | A 'Generic'-based implementation of 'fromForm'.

341-- | A 'Generic'-based implementation of 'fromForm'.

331-- This is used as a default implementation in 'FromForm'.

342-- This is used as a default implementation in 'FromForm'.

343+--

344+-- Note that this only works for records (i.e. product data types with named fields):

345+--

346+-- @

347+-- data Person = Person

348+-- { name :: String

349+-- , age :: Int

350+-- } deriving ('Generic')

351+-- @

332genericFromForm :: (Generic a, GFromForm (Rep a))

352genericFromForm :: (Generic a, GFromForm (Rep a))

333 => Form -> Either Text a

353 => Form -> Either Text a

334genericFromForm f = to <$> gFromForm f

354genericFromForm f = to <$> gFromForm f