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Add safeLink'

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Resolves #952
This commit is contained in:
Oleg Grenrus 2018-06-01 12:50:46 +03:00
parent a66aa8a981
commit 46663f29b0
2 changed files with 124 additions and 76 deletions
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198
servant/src/Servant/Utils/Links.hs
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@ -19,8 +19,6 @@
-- >>> import Servant.Utils.Links
-- >>> import Data.Proxy
-- >>>
-- >>>
-- >>>
-- >>> type Hello = "hello" :> Get '[JSON] Int
-- >>> type Bye = "bye" :> QueryParam "name" String :> Delete '[JSON] NoContent
-- >>> type API = Hello :<|> Bye
@ -63,10 +61,24 @@
-- >>> :set -XConstraintKinds
-- >>> :{
-- >>> let apiLink :: (IsElem endpoint API, HasLink endpoint)
-- >>> => Proxy endpoint -> MkLink endpoint
-- >>> => Proxy endpoint -> MkLink endpoint Link
-- >>> apiLink = safeLink api
-- >>> :}
--
-- `safeLink'` allows to make specialise the output:
--
-- >>> safeLink' toUrlPiece api without
-- "bye"
--
-- >>> :{
-- >>> let apiTextLink :: (IsElem endpoint API, HasLink endpoint)
-- >>> => Proxy endpoint -> MkLink endpoint Text
-- >>> apiTextLink = safeLink' toUrlPiece api
-- >>> :}
--
-- >>> apiTextLink without
-- "bye"
--
-- Attempting to construct a link to an endpoint that does not exist in api
-- will result in a type error like this:
--
@ -86,7 +98,9 @@ module Servant.Utils.Links (
--
-- | Note that 'URI' is from the "Network.URI" module in the @network-uri@ package.
safeLink
, safeLink'
, allLinks
, allLinks'
, URI(..)
-- * Adding custom types
, HasLink(..)
@ -109,8 +123,6 @@ import Data.Singletons.Bool
(SBool (..), SBoolI (..))
import qualified Data.Text as Text
import qualified Data.Text.Encoding as TE
import Data.Type.Bool
(If)
import Data.Type.Bool
(If)
import GHC.TypeLits
@ -278,8 +290,18 @@ safeLink
:: forall endpoint api. (IsElem endpoint api, HasLink endpoint)
=> Proxy api -- ^ The whole API that this endpoint is a part of
-> Proxy endpoint -- ^ The API endpoint you would like to point to
-> MkLink endpoint
safeLink _ endpoint = toLink endpoint (Link mempty mempty)
-> MkLink endpoint Link
safeLink = safeLink' id
-- | More general 'safeLink'.
--
safeLink'
:: forall endpoint api a. (IsElem endpoint api, HasLink endpoint)
=> (Link -> a)
-> Proxy api -- ^ The whole API that this endpoint is a part of
-> Proxy endpoint -- ^ The API endpoint you would like to point to
-> MkLink endpoint a
safeLink' toA _ endpoint = toLink toA endpoint (Link mempty mempty)
-- | Create all links in an API.
--
@ -295,37 +317,47 @@ safeLink _ endpoint = toLink endpoint (Link mempty mempty)
--
-- Note: nested APIs don't work well with this approach
--
-- >>> :kind! MkLink (Capture "nest" Char :> (Capture "x" Int :> Get '[JSON] Int :<|> Capture "y" Double :> Get '[JSON] Double))
-- MkLink (Capture "nest" Char :> (Capture "x" Int :> Get '[JSON] Int :<|> Capture "y" Double :> Get '[JSON] Double)) :: *
-- >>> :kind! MkLink (Capture "nest" Char :> (Capture "x" Int :> Get '[JSON] Int :<|> Capture "y" Double :> Get '[JSON] Double)) Link
-- MkLink (Capture "nest" Char :> (Capture "x" Int :> Get '[JSON] Int :<|> Capture "y" Double :> Get '[JSON] Double)) Link :: *
-- = Char -> (Int -> Link) :<|> (Double -> Link)
--
allLinks
:: forall api. HasLink api
=> Proxy api
-> MkLink api
allLinks api = toLink api (Link mempty mempty)
-> MkLink api Link
allLinks = allLinks' id
-- | More general 'allLinks'. See `safeLink'`.
allLinks'
:: forall api a. HasLink api
=> (Link -> a)
-> Proxy api
-> MkLink api a
allLinks' toA api = toLink toA api (Link mempty mempty)
-- | Construct a toLink for an endpoint.
class HasLink endpoint where
type MkLink endpoint
toLink :: Proxy endpoint -- ^ The API endpoint you would like to point to
-> Link
-> MkLink endpoint
type MkLink endpoint (a :: *)
toLink
:: (Link -> a)
-> Proxy endpoint -- ^ The API endpoint you would like to point to
-> Link
-> MkLink endpoint a
-- Naked symbol instance
instance (KnownSymbol sym, HasLink sub) => HasLink (sym :> sub) where
type MkLink (sym :> sub) = MkLink sub
toLink _ =
toLink (Proxy :: Proxy sub) . addSegment (escaped seg)
type MkLink (sym :> sub) a = MkLink sub a
toLink toA _ =
toLink toA (Proxy :: Proxy sub) . addSegment (escaped seg)
where
seg = symbolVal (Proxy :: Proxy sym)
-- QueryParam instances
instance (KnownSymbol sym, ToHttpApiData v, HasLink sub, SBoolI (FoldRequired mods))
=> HasLink (QueryParam' mods sym v :> sub) where
type MkLink (QueryParam' mods sym v :> sub) = If (FoldRequired mods) v (Maybe v) -> MkLink sub
toLink _ l mv =
toLink (Proxy :: Proxy sub) $
=> HasLink (QueryParam' mods sym v :> sub)
where
type MkLink (QueryParam' mods sym v :> sub) a = If (FoldRequired mods) v (Maybe v) -> MkLink sub a
toLink toA _ l mv =
toLink toA (Proxy :: Proxy sub) $
case sbool :: SBool (FoldRequired mods) of
STrue -> (addQueryParam . SingleParam k . toQueryParam) mv l
SFalse -> maybe id (addQueryParam . SingleParam k . toQueryParam) mv l
@ -334,105 +366,121 @@ instance (KnownSymbol sym, ToHttpApiData v, HasLink sub, SBoolI (FoldRequired mo
k = symbolVal (Proxy :: Proxy sym)
instance (KnownSymbol sym, ToHttpApiData v, HasLink sub)
=> HasLink (QueryParams sym v :> sub) where
type MkLink (QueryParams sym v :> sub) = [v] -> MkLink sub
toLink _ l =
toLink (Proxy :: Proxy sub) .
=> HasLink (QueryParams sym v :> sub)
where
type MkLink (QueryParams sym v :> sub) a = [v] -> MkLink sub a
toLink toA _ l =
toLink toA (Proxy :: Proxy sub) .
foldl' (\l' v -> addQueryParam (ArrayElemParam k (toQueryParam v)) l') l
where
k = symbolVal (Proxy :: Proxy sym)
instance (KnownSymbol sym, HasLink sub)
=> HasLink (QueryFlag sym :> sub) where
type MkLink (QueryFlag sym :> sub) = Bool -> MkLink sub
toLink _ l False =
toLink (Proxy :: Proxy sub) l
toLink _ l True =
toLink (Proxy :: Proxy sub) $ addQueryParam (FlagParam k) l
=> HasLink (QueryFlag sym :> sub)
where
type MkLink (QueryFlag sym :> sub) a = Bool -> MkLink sub a
toLink toA _ l False =
toLink toA (Proxy :: Proxy sub) l
toLink toA _ l True =
toLink toA (Proxy :: Proxy sub) $ addQueryParam (FlagParam k) l
where
k = symbolVal (Proxy :: Proxy sym)
-- :<|> instance - Generate all links at once
instance (HasLink a, HasLink b) => HasLink (a :<|> b) where
type MkLink (a :<|> b) = MkLink a :<|> MkLink b
toLink _ l = toLink (Proxy :: Proxy a) l :<|> toLink (Proxy :: Proxy b) l
type MkLink (a :<|> b) r = MkLink a r :<|> MkLink b r
toLink toA _ l = toLink toA (Proxy :: Proxy a) l :<|> toLink toA (Proxy :: Proxy b) l
-- Misc instances
instance HasLink sub => HasLink (ReqBody' mods ct a :> sub) where
type MkLink (ReqBody' mods ct a :> sub) = MkLink sub
toLink _ = toLink (Proxy :: Proxy sub)
type MkLink (ReqBody' mods ct a :> sub) r = MkLink sub r
toLink toA _ = toLink toA (Proxy :: Proxy sub)
instance (ToHttpApiData v, HasLink sub)
=> HasLink (Capture' mods sym v :> sub) where
type MkLink (Capture' mods sym v :> sub) = v -> MkLink sub
toLink _ l v =
toLink (Proxy :: Proxy sub) $
=> HasLink (Capture' mods sym v :> sub)
where
type MkLink (Capture' mods sym v :> sub) a = v -> MkLink sub a
toLink toA _ l v =
toLink toA (Proxy :: Proxy sub) $
addSegment (escaped . Text.unpack $ toUrlPiece v) l
instance (ToHttpApiData v, HasLink sub)
=> HasLink (CaptureAll sym v :> sub) where
type MkLink (CaptureAll sym v :> sub) = [v] -> MkLink sub
toLink _ l vs =
toLink (Proxy :: Proxy sub) $
foldl' (flip $ addSegment . escaped . Text.unpack . toUrlPiece) l vs
=> HasLink (CaptureAll sym v :> sub)
where
type MkLink (CaptureAll sym v :> sub) a = [v] -> MkLink sub a
toLink toA _ l vs = toLink toA (Proxy :: Proxy sub) $
foldl' (flip $ addSegment . escaped . Text.unpack . toUrlPiece) l vs
instance HasLink sub => HasLink (Header' mods sym a :> sub) where
type MkLink (Header' mods sym a :> sub) = MkLink sub
toLink _ = toLink (Proxy :: Proxy sub)
instance HasLink sub => HasLink (Header' mods sym (a :: *) :> sub) where
type MkLink (Header' mods sym a :> sub) r = MkLink sub r
toLink = simpleToLink (Proxy :: Proxy sub)
instance HasLink sub => HasLink (Vault :> sub) where
type MkLink (Vault :> sub) = MkLink sub
toLink _ = toLink (Proxy :: Proxy sub)
type MkLink (Vault :> sub) a = MkLink sub a
toLink = simpleToLink (Proxy :: Proxy sub)
instance HasLink sub => HasLink (Description s :> sub) where
type MkLink (Description s :> sub) = MkLink sub
toLink _ = toLink (Proxy :: Proxy sub)
type MkLink (Description s :> sub) a = MkLink sub a
toLink = simpleToLink (Proxy :: Proxy sub)
instance HasLink sub => HasLink (Summary s :> sub) where
type MkLink (Summary s :> sub) = MkLink sub
toLink _ = toLink (Proxy :: Proxy sub)
type MkLink (Summary s :> sub) a = MkLink sub a
toLink = simpleToLink (Proxy :: Proxy sub)
instance HasLink sub => HasLink (HttpVersion :> sub) where
type MkLink (HttpVersion:> sub) = MkLink sub
toLink _ = toLink (Proxy :: Proxy sub)
type MkLink (HttpVersion:> sub) a = MkLink sub a
toLink = simpleToLink (Proxy :: Proxy sub)
instance HasLink sub => HasLink (IsSecure :> sub) where
type MkLink (IsSecure :> sub) = MkLink sub
toLink _ = toLink (Proxy :: Proxy sub)
type MkLink (IsSecure :> sub) a = MkLink sub a
toLink = simpleToLink (Proxy :: Proxy sub)
instance HasLink sub => HasLink (WithNamedContext name context sub) where
type MkLink (WithNamedContext name context sub) = MkLink sub
toLink _ = toLink (Proxy :: Proxy sub)
type MkLink (WithNamedContext name context sub) a = MkLink sub a
toLink toA _ = toLink toA (Proxy :: Proxy sub)
instance HasLink sub => HasLink (RemoteHost :> sub) where
type MkLink (RemoteHost :> sub) = MkLink sub
toLink _ = toLink (Proxy :: Proxy sub)
type MkLink (RemoteHost :> sub) a = MkLink sub a
toLink = simpleToLink (Proxy :: Proxy sub)
instance HasLink sub => HasLink (BasicAuth realm a :> sub) where
type MkLink (BasicAuth realm a :> sub) = MkLink sub
toLink _ = toLink (Proxy :: Proxy sub)
type MkLink (BasicAuth realm a :> sub) r = MkLink sub r
toLink = simpleToLink (Proxy :: Proxy sub)
instance HasLink EmptyAPI where
type MkLink EmptyAPI = EmptyAPI
toLink _ _ = EmptyAPI
type MkLink EmptyAPI a = EmptyAPI
toLink _ _ _ = EmptyAPI
-- Verb (terminal) instances
instance HasLink (Verb m s ct a) where
type MkLink (Verb m s ct a) = Link
toLink _ = id
type MkLink (Verb m s ct a) r = r
toLink toA _ = toA
instance HasLink Raw where
type MkLink Raw = Link
toLink _ = id
type MkLink Raw a = a
toLink toA _ = toA
instance HasLink (Stream m fr ct a) where
type MkLink (Stream m fr ct a) = Link
toLink _ = id
type MkLink (Stream m fr ct a) r = r
toLink toA _ = toA
-- AuthProtext instances
instance HasLink sub => HasLink (AuthProtect tag :> sub) where
type MkLink (AuthProtect tag :> sub) = MkLink sub
toLink _ = toLink (Proxy :: Proxy sub)
type MkLink (AuthProtect tag :> sub) a = MkLink sub a
toLink = simpleToLink (Proxy :: Proxy sub)
-- | Helper for implemneting 'toLink' for combinators not affecting link
-- structure.
simpleToLink
:: forall sub a combinator.
(HasLink sub, MkLink sub a ~ MkLink (combinator :> sub) a)
=> Proxy sub
-> (Link -> a)
-> Proxy (combinator :> sub)
-> Link
-> MkLink (combinator :> sub) a
simpleToLink _ toA _ = toLink toA (Proxy :: Proxy sub)
-- $setup
-- >>> import Servant.API

2
servant/test/Servant/Utils/LinksSpec.hs
View file

@ -41,7 +41,7 @@ type LinkableApi =
apiLink :: (IsElem endpoint TestApi, HasLink endpoint)
=> Proxy endpoint -> MkLink endpoint
=> Proxy endpoint -> MkLink endpoint Link
apiLink = safeLink (Proxy :: Proxy TestApi)
-- | Convert a link to a URI and ensure that this maps to the given string