Servant.API.ContentTypes

A collection of basic Content-Types (also known as Internet Media Types, or MIME types). Additionally, this module provides classes that encapsulate how to serialize or deserialize values to or from a particular Content-Type.

Content-Types are used in ReqBody and the method combinators:

>>> type MyEndpoint = ReqBody '[JSON, PlainText] Book :> Get '[JSON, PlainText] Book

Meaning the endpoint accepts requests of Content-Type application/json or text/plain;charset-utf8, and returns data in either one of those formats (depending on the Accept header).

If you would like to support Content-Types beyond those provided here, then:

1. Declare a new data type with no constructors (e.g. data HTML).
2. Make an instance of it for Accept.
3. If you want to be able to serialize data *into* that Content-Type, make an instance of it for MimeRender.
4. If you want to be able to deserialize data *from* that Content-Type, make an instance of it for MimeUnrender.

Note that roles are reversed in servant-server and servant-client: to be able to serve (or even typecheck) a Get '[JSON, XML] MyData, you'll need to have the appropriate MimeRender instances in scope, whereas to query that endpoint with servant-client, you'll need a MimeUnrender instance in scope.

Provided Content-Types

data JSON

Instances

Accept JSON

application/json

Defined in Servant.API.ContentTypes

Methods

contentType :: Proxy JSON -> MediaType

contentTypes :: Proxy JSON -> NonEmpty MediaType

FromJSON a => MimeUnrender JSON a

eitherDecode

Defined in Servant.API.ContentTypes

Methods

mimeUnrender :: Proxy JSON -> ByteString -> Either String a

mimeUnrenderWithType :: Proxy JSON -> MediaType -> ByteString -> Either String a

ToJSON a => MimeRender JSON a

encode

Defined in Servant.API.ContentTypes

Methods

mimeRender :: Proxy JSON -> a -> ByteString

data PlainText

Instances

Accept PlainText

text/plain;charset=utf-8

Defined in Servant.API.ContentTypes

Methods

contentType :: Proxy PlainText -> MediaType

contentTypes :: Proxy PlainText -> NonEmpty MediaType

MimeUnrender PlainText String

Right . BC.unpack

Defined in Servant.API.ContentTypes

Methods

mimeUnrender :: Proxy PlainText -> ByteString -> Either String String

mimeUnrenderWithType :: Proxy PlainText -> MediaType -> ByteString -> Either String String

MimeUnrender PlainText Text

left show . TextS.decodeUtf8' . toStrict

Defined in Servant.API.ContentTypes

Methods

mimeUnrender :: Proxy PlainText -> ByteString -> Either String Text

mimeUnrenderWithType :: Proxy PlainText -> MediaType -> ByteString -> Either String Text

MimeUnrender PlainText Text

left show . TextL.decodeUtf8'

Defined in Servant.API.ContentTypes

Methods

mimeUnrender :: Proxy PlainText -> ByteString -> Either String Text

mimeUnrenderWithType :: Proxy PlainText -> MediaType -> ByteString -> Either String Text

MimeRender PlainText String

BC.pack

Defined in Servant.API.ContentTypes

Methods

mimeRender :: Proxy PlainText -> String -> ByteString

MimeRender PlainText Text

fromStrict . TextS.encodeUtf8

Defined in Servant.API.ContentTypes

Methods

mimeRender :: Proxy PlainText -> Text -> ByteString

MimeRender PlainText Text

encodeUtf8

Defined in Servant.API.ContentTypes

Methods

mimeRender :: Proxy PlainText -> Text -> ByteString

data FormUrlEncoded

Instances

Accept FormUrlEncoded

application/x-www-form-urlencoded

Defined in Servant.API.ContentTypes

Methods

contentType :: Proxy FormUrlEncoded -> MediaType

contentTypes :: Proxy FormUrlEncoded -> NonEmpty MediaType

FromForm a => MimeUnrender FormUrlEncoded a

urlDecodeAsForm Note that the mimeUnrender p (mimeRender p x) == Right x law only holds if every element of x is non-null (i.e., not ("", ""))

Defined in Servant.API.ContentTypes

Methods

mimeUnrender :: Proxy FormUrlEncoded -> ByteString -> Either String a

mimeUnrenderWithType :: Proxy FormUrlEncoded -> MediaType -> ByteString -> Either String a

ToForm a => MimeRender FormUrlEncoded a

urlEncodeAsForm Note that the mimeUnrender p (mimeRender p x) == Right x law only holds if every element of x is non-null (i.e., not ("", ""))

Defined in Servant.API.ContentTypes

Methods

mimeRender :: Proxy FormUrlEncoded -> a -> ByteString

data OctetStream

Instances

Accept OctetStream

application/octet-stream

Defined in Servant.API.ContentTypes

Methods

contentType :: Proxy OctetStream -> MediaType

contentTypes :: Proxy OctetStream -> NonEmpty MediaType

MimeUnrender OctetStream ByteString

Right . toStrict

Defined in Servant.API.ContentTypes

Methods

mimeUnrender :: Proxy OctetStream -> ByteString0 -> Either String ByteString

mimeUnrenderWithType :: Proxy OctetStream -> MediaType -> ByteString0 -> Either String ByteString

MimeUnrender OctetStream ByteString

Right . id

Defined in Servant.API.ContentTypes

Methods

mimeUnrender :: Proxy OctetStream -> ByteString -> Either String ByteString

mimeUnrenderWithType :: Proxy OctetStream -> MediaType -> ByteString -> Either String ByteString

MimeRender OctetStream ByteString

fromStrict

Defined in Servant.API.ContentTypes

Methods

mimeRender :: Proxy OctetStream -> ByteString -> ByteString0

MimeRender OctetStream ByteString

id

Defined in Servant.API.ContentTypes

Methods

mimeRender :: Proxy OctetStream -> ByteString -> ByteString

Building your own Content-Type

class Accept ctype where

Instances of Accept represent mimetypes. They are used for matching against the Accept HTTP header of the request, and for setting the Content-Type header of the response

Example:

>>> import Network.HTTP.Media ((//), (/:))
>>> data HTML
>>> :{
instance Accept HTML where
   contentType _ = "text" // "html" /: ("charset", "utf-8")
:}

Minimal complete definition

contentType | contentTypes

Methods

contentType :: Proxy ctype -> MediaType

contentTypes :: Proxy ctype -> NonEmpty MediaType

Instances

Accept OctetStream

application/octet-stream

Defined in Servant.API.ContentTypes

Methods

contentType :: Proxy OctetStream -> MediaType

contentTypes :: Proxy OctetStream -> NonEmpty MediaType

Accept FormUrlEncoded

application/x-www-form-urlencoded

Defined in Servant.API.ContentTypes

Methods

contentType :: Proxy FormUrlEncoded -> MediaType

contentTypes :: Proxy FormUrlEncoded -> NonEmpty MediaType

Accept PlainText

text/plain;charset=utf-8

Defined in Servant.API.ContentTypes

Methods

contentType :: Proxy PlainText -> MediaType

contentTypes :: Proxy PlainText -> NonEmpty MediaType

Accept JSON

application/json

Defined in Servant.API.ContentTypes

Methods

contentType :: Proxy JSON -> MediaType

contentTypes :: Proxy JSON -> NonEmpty MediaType

class Accept ctype => MimeRender ctype a where

Instantiate this class to register a way of serializing a type based on the Accept header.

Example:

data MyContentType

instance Accept MyContentType where
   contentType _ = "example" // "prs.me.mine" /: ("charset", "utf-8")

instance Show a => MimeRender MyContentType a where
   mimeRender _ val = pack ("This is MINE! " ++ show val)

type MyAPI = "path" :> Get '[MyContentType] Int

Minimal complete definition

mimeRender

Methods

mimeRender :: Proxy ctype -> a -> ByteString

Instances

MimeRender OctetStream ByteString

fromStrict

Defined in Servant.API.ContentTypes

Methods

mimeRender :: Proxy OctetStream -> ByteString -> ByteString0

MimeRender OctetStream ByteString

id

Defined in Servant.API.ContentTypes

Methods

mimeRender :: Proxy OctetStream -> ByteString -> ByteString

ToForm a => MimeRender FormUrlEncoded a

urlEncodeAsForm Note that the mimeUnrender p (mimeRender p x) == Right x law only holds if every element of x is non-null (i.e., not ("", ""))

Defined in Servant.API.ContentTypes

Methods

mimeRender :: Proxy FormUrlEncoded -> a -> ByteString

MimeRender PlainText String

BC.pack

Defined in Servant.API.ContentTypes

Methods

mimeRender :: Proxy PlainText -> String -> ByteString

MimeRender PlainText Text

fromStrict . TextS.encodeUtf8

Defined in Servant.API.ContentTypes

Methods

mimeRender :: Proxy PlainText -> Text -> ByteString

MimeRender PlainText Text

encodeUtf8

Defined in Servant.API.ContentTypes

Methods

mimeRender :: Proxy PlainText -> Text -> ByteString

ToJSON a => MimeRender JSON a

encode

Defined in Servant.API.ContentTypes

Methods

mimeRender :: Proxy JSON -> a -> ByteString

class Accept ctype => MimeUnrender ctype a where

Instantiate this class to register a way of deserializing a type based on the request's Content-Type header.

>>> import Network.HTTP.Media hiding (Accept)
>>> import qualified Data.ByteString.Lazy.Char8 as BSC
>>> data MyContentType = MyContentType String

>>> :{
instance Accept MyContentType where
   contentType _ = "example" // "prs.me.mine" /: ("charset", "utf-8")
:}

>>> :{
instance Read a => MimeUnrender MyContentType a where
   mimeUnrender _ bs = case BSC.take 12 bs of
     "MyContentType" -> return . read . BSC.unpack $ BSC.drop 12 bs
     _ -> Left "didn't start with the magic incantation"
:}

>>> type MyAPI = "path" :> ReqBody '[MyContentType] Int :> Get '[JSON] Int

Minimal complete definition

mimeUnrender | mimeUnrenderWithType

Methods

mimeUnrender :: Proxy ctype -> ByteString -> Either String a

mimeUnrenderWithType :: Proxy ctype -> MediaType -> ByteString -> Either String a

Variant which is given the actual MediaType provided by the other party.

In the most cases you don't want to branch based on the MediaType. See pr552 for a motivating example.

Instances

MimeUnrender OctetStream ByteString

Right . toStrict

Defined in Servant.API.ContentTypes

Methods

mimeUnrender :: Proxy OctetStream -> ByteString0 -> Either String ByteString

mimeUnrenderWithType :: Proxy OctetStream -> MediaType -> ByteString0 -> Either String ByteString

MimeUnrender OctetStream ByteString

Right . id

Defined in Servant.API.ContentTypes

Methods

mimeUnrender :: Proxy OctetStream -> ByteString -> Either String ByteString

mimeUnrenderWithType :: Proxy OctetStream -> MediaType -> ByteString -> Either String ByteString

FromForm a => MimeUnrender FormUrlEncoded a

urlDecodeAsForm Note that the mimeUnrender p (mimeRender p x) == Right x law only holds if every element of x is non-null (i.e., not ("", ""))

Defined in Servant.API.ContentTypes

Methods

mimeUnrender :: Proxy FormUrlEncoded -> ByteString -> Either String a

mimeUnrenderWithType :: Proxy FormUrlEncoded -> MediaType -> ByteString -> Either String a

MimeUnrender PlainText String

Right . BC.unpack

Defined in Servant.API.ContentTypes

Methods

mimeUnrender :: Proxy PlainText -> ByteString -> Either String String

mimeUnrenderWithType :: Proxy PlainText -> MediaType -> ByteString -> Either String String

MimeUnrender PlainText Text

left show . TextS.decodeUtf8' . toStrict

Defined in Servant.API.ContentTypes

Methods

mimeUnrender :: Proxy PlainText -> ByteString -> Either String Text

mimeUnrenderWithType :: Proxy PlainText -> MediaType -> ByteString -> Either String Text

MimeUnrender PlainText Text

left show . TextL.decodeUtf8'

Defined in Servant.API.ContentTypes

Methods

mimeUnrender :: Proxy PlainText -> ByteString -> Either String Text

mimeUnrenderWithType :: Proxy PlainText -> MediaType -> ByteString -> Either String Text

FromJSON a => MimeUnrender JSON a

eitherDecode

Defined in Servant.API.ContentTypes

Methods

mimeUnrender :: Proxy JSON -> ByteString -> Either String a

mimeUnrenderWithType :: Proxy JSON -> MediaType -> ByteString -> Either String a

NoContent

data NoContent

A type for responses without content-body.

Constructors

NoContent

Instances

Eq NoContent

Defined in Servant.API.ContentTypes

Methods

(==) :: NoContent -> NoContent -> Bool

(/=) :: NoContent -> NoContent -> Bool

Read NoContent

Defined in Servant.API.ContentTypes

Methods

readsPrec :: Int -> ReadS NoContent

readList :: ReadS [NoContent]

readPrec :: ReadPrec NoContent

readListPrec :: ReadPrec [NoContent]

Show NoContent

Defined in Servant.API.ContentTypes

Methods

showsPrec :: Int -> NoContent -> ShowS

show :: NoContent -> String

showList :: [NoContent] -> ShowS

Generic NoContent

Defined in Servant.API.ContentTypes

Associated Types

type Rep NoContent :: * -> *

Methods

from :: NoContent -> Rep NoContent x

to :: Rep NoContent x -> NoContent

AllMime (ctyp ': (ctyp' ': ctyps)) => AllMimeRender (ctyp ': (ctyp' ': ctyps)) NoContent

Defined in Servant.API.ContentTypes

Methods

allMimeRender :: Proxy (ctyp ': (ctyp' ': ctyps)) -> NoContent -> [(MediaType, ByteString)]

Accept ctyp => AllMimeRender (ctyp ': ([] :: [*])) NoContent

Defined in Servant.API.ContentTypes

Methods

allMimeRender :: Proxy (ctyp ': []) -> NoContent -> [(MediaType, ByteString)]

type Rep NoContent

Defined in Servant.API.ContentTypes

type Rep NoContent = D1 (MetaData "NoContent" "Servant.API.ContentTypes" "servant-0.14.1-EgbVaicHQEdCgqTzWc4SOj" False) (C1 (MetaCons "NoContent" PrefixI False) (U1 :: * -> *))

Internal

newtype AcceptHeader

Constructors

AcceptHeader ByteString

Instances

Eq AcceptHeader

Defined in Servant.API.ContentTypes

Methods

(==) :: AcceptHeader -> AcceptHeader -> Bool

(/=) :: AcceptHeader -> AcceptHeader -> Bool

Read AcceptHeader

Defined in Servant.API.ContentTypes

Methods

readsPrec :: Int -> ReadS AcceptHeader

readList :: ReadS [AcceptHeader]

readPrec :: ReadPrec AcceptHeader

readListPrec :: ReadPrec [AcceptHeader]

Show AcceptHeader

Defined in Servant.API.ContentTypes

Methods

showsPrec :: Int -> AcceptHeader -> ShowS

show :: AcceptHeader -> String

showList :: [AcceptHeader] -> ShowS

Generic AcceptHeader

Defined in Servant.API.ContentTypes

Associated Types

type Rep AcceptHeader :: * -> *

Methods

from :: AcceptHeader -> Rep AcceptHeader x

to :: Rep AcceptHeader x -> AcceptHeader

type Rep AcceptHeader

Defined in Servant.API.ContentTypes

type Rep AcceptHeader = D1 (MetaData "AcceptHeader" "Servant.API.ContentTypes" "servant-0.14.1-EgbVaicHQEdCgqTzWc4SOj" True) (C1 (MetaCons "AcceptHeader" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 ByteString)))

class AllMime list => AllCTRender (list :: [*]) a where

Minimal complete definition

handleAcceptH

Methods

handleAcceptH :: Proxy list -> AcceptHeader -> a -> Maybe (ByteString, ByteString)

Instances

(TypeError (Text "No instance for (), use NoContent instead.") :: Constraint) => AllCTRender ([] :: [*]) ()

Defined in Servant.API.ContentTypes

Methods

handleAcceptH :: Proxy [] -> AcceptHeader -> () -> Maybe (ByteString, ByteString)

(Accept ct, AllMime cts, AllMimeRender (ct ': cts) a) => AllCTRender (ct ': cts) a

Defined in Servant.API.ContentTypes

Methods

handleAcceptH :: Proxy (ct ': cts) -> AcceptHeader -> a -> Maybe (ByteString, ByteString)

class AllCTUnrender (list :: [*]) a where

Minimal complete definition

canHandleCTypeH

Methods

canHandleCTypeH :: Proxy list -> ByteString -> Maybe (ByteString -> Either String a)

handleCTypeH :: Proxy list -> ByteString -> ByteString -> Maybe (Either String a)

Instances

AllMimeUnrender ctyps a => AllCTUnrender ctyps a

Defined in Servant.API.ContentTypes

Methods

canHandleCTypeH :: Proxy ctyps -> ByteString -> Maybe (ByteString -> Either String a)

handleCTypeH :: Proxy ctyps -> ByteString -> ByteString -> Maybe (Either String a)

class AllMime (list :: [*]) where

Minimal complete definition

allMime

Methods

allMime :: Proxy list -> [MediaType]

Instances

AllMime ([] :: [*])

Defined in Servant.API.ContentTypes

Methods

allMime :: Proxy [] -> [MediaType]

(Accept ctyp, AllMime ctyps) => AllMime (ctyp ': ctyps)

Defined in Servant.API.ContentTypes

Methods

allMime :: Proxy (ctyp ': ctyps) -> [MediaType]

class AllMime list => AllMimeRender (list :: [*]) a where

Minimal complete definition

allMimeRender

Methods

allMimeRender :: Proxy list -> a -> [(MediaType, ByteString)]

Instances

AllMime (ctyp ': (ctyp' ': ctyps)) => AllMimeRender (ctyp ': (ctyp' ': ctyps)) NoContent

Defined in Servant.API.ContentTypes

Methods

allMimeRender :: Proxy (ctyp ': (ctyp' ': ctyps)) -> NoContent -> [(MediaType, ByteString)]

Accept ctyp => AllMimeRender (ctyp ': ([] :: [*])) NoContent

Defined in Servant.API.ContentTypes

Methods

allMimeRender :: Proxy (ctyp ': []) -> NoContent -> [(MediaType, ByteString)]

(MimeRender ctyp a, AllMimeRender (ctyp' ': ctyps) a) => AllMimeRender (ctyp ': (ctyp' ': ctyps)) a

Defined in Servant.API.ContentTypes

Methods

allMimeRender :: Proxy (ctyp ': (ctyp' ': ctyps)) -> a -> [(MediaType, ByteString)]

MimeRender ctyp a => AllMimeRender (ctyp ': ([] :: [*])) a

Defined in Servant.API.ContentTypes

Methods

allMimeRender :: Proxy (ctyp ': []) -> a -> [(MediaType, ByteString)]

class AllMime list => AllMimeUnrender (list :: [*]) a where

Minimal complete definition

allMimeUnrender

Methods

allMimeUnrender :: Proxy list -> [(MediaType, ByteString -> Either String a)]

Instances

AllMimeUnrender ([] :: [*]) a

Defined in Servant.API.ContentTypes

Methods

allMimeUnrender :: Proxy [] -> [(MediaType, ByteString -> Either String a)]

(MimeUnrender ctyp a, AllMimeUnrender ctyps a) => AllMimeUnrender (ctyp ': ctyps) a

Defined in Servant.API.ContentTypes

Methods

allMimeUnrender :: Proxy (ctyp ': ctyps) -> [(MediaType, ByteString -> Either String a)]

eitherDecodeLenient :: FromJSON a => ByteString -> Either String a

Like eitherDecode but allows all JSON values instead of just objects and arrays.

Will handle trailing whitespace, but not trailing junk. ie.

>>> eitherDecodeLenient "1 " :: Either String Int
Right 1

>>> eitherDecodeLenient "1 junk" :: Either String Int
Left "trailing junk after valid JSON: endOfInput"

canHandleAcceptH :: AllMime list => Proxy list -> AcceptHeader -> Bool