Servant.Client

This module provides client which can automatically generate querying functions for each endpoint just from the type representing your API.

Documentation

type family AuthClientData a :: *

For a resource protected by authentication (e.g. AuthProtect), we need to provide the client with some data used to add authentication data to a request

NOTE: THIS API IS EXPERIMENTAL AND SUBJECT TO CHANGE

newtype AuthenticateReq a

For better type inference and to avoid usage of a data family, we newtype wrap the combination of some AuthClientData and a function to add authentication data to a request

NOTE: THIS API IS EXPERIMENTAL AND SUBJECT TO CHANGE

Constructors

AuthenticateReq

Fields

unAuthReq :: (AuthClientData a, AuthClientData a -> Req -> Req)

client :: HasClient layout => Proxy layout -> BaseUrl -> Manager -> Client layout

client allows you to produce operations to query an API from a client.

type MyApi = "books" :> Get '[JSON] [Book] -- GET /books
        :<|> "books" :> ReqBody '[JSON] Book :> Post '[JSON] Book -- POST /books

myApi :: Proxy MyApi
myApi = Proxy

getAllBooks :: ExceptT String IO [Book]
postNewBook :: Book -> ExceptT String IO Book
(getAllBooks :<|> postNewBook) = client myApi host manager
  where host = BaseUrl Http "localhost" 8080

class HasClient layout where

This class lets us define how each API combinator influences the creation of an HTTP request. It's mostly an internal class, you can just use client.

Associated Types

type Client layout :: *

Methods

clientWithRoute :: Proxy layout -> Req -> BaseUrl -> Manager -> Client layout

Instances

HasClient * Raw

Pick a Method and specify where the server you want to query is. You get back the full Response.

(HasClient * a, HasClient * b) => HasClient * ((:<|>) a b)

A client querying function for a :<|> b will actually hand you one function for querying a and another one for querying b, stitching them together with :<|>, which really is just like a pair.

type MyApi = "books" :> Get '[JSON] [Book] -- GET /books
        :<|> "books" :> ReqBody '[JSON] Book :> Post Book -- POST /books

myApi :: Proxy MyApi
myApi = Proxy

getAllBooks :: ExceptT String IO [Book]
postNewBook :: Book -> ExceptT String IO Book
(getAllBooks :<|> postNewBook) = client myApi host manager
  where host = BaseUrl Http "localhost" 8080

HasClient * subapi => HasClient * (WithNamedContext name context subapi)

HasClient k api => HasClient * ((:>) * k (BasicAuth realm usr) api)

HasClient k api => HasClient * ((:>) * k (AuthProtect k tag) api)

HasClient k api => HasClient * ((:>) * k IsSecure api)

HasClient k api => HasClient * ((:>) * k RemoteHost api)

HasClient k api => HasClient * ((:>) * k Vault api)

(MimeRender * ct a, HasClient k sublayout) => HasClient * ((:>) * k (ReqBody * ((:) * ct cts) a) sublayout)

If you use a ReqBody in one of your endpoints in your API, the corresponding querying function will automatically take an additional argument of the type specified by your ReqBody. That function will take care of encoding this argument as JSON and of using it as the request body.

All you need is for your type to have a ToJSON instance.

Example:

type MyApi = "books" :> ReqBody '[JSON] Book :> Post '[JSON] Book

myApi :: Proxy MyApi
myApi = Proxy

addBook :: Book -> ExceptT String IO Book
addBook = client myApi host manager
  where host = BaseUrl Http "localhost" 8080
-- then you can just use "addBook" to query that endpoint

(KnownSymbol sym, HasClient k sublayout) => HasClient * ((:>) * k (QueryFlag sym) sublayout)

If you use a QueryFlag in one of your endpoints in your API, the corresponding querying function will automatically take an additional Bool argument.

If you give False, nothing will be added to the query string.

Otherwise, this function will insert a value-less query string parameter under the name associated to your QueryFlag.

Example:

type MyApi = "books" :> QueryFlag "published" :> Get '[JSON] [Book]

myApi :: Proxy MyApi
myApi = Proxy

getBooks :: Bool -> ExceptT String IO [Book]
getBooks = client myApi host
  where host = BaseUrl Http "localhost" 8080
-- then you can just use "getBooks" to query that endpoint.
-- 'getBooksBy False' for all books
-- 'getBooksBy True' to only get _already published_ books

(KnownSymbol sym, ToHttpApiData a, HasClient k sublayout) => HasClient * ((:>) * k (QueryParams * sym a) sublayout)

If you use a QueryParams in one of your endpoints in your API, the corresponding querying function will automatically take an additional argument, a list of values of the type specified by your QueryParams.

If you give an empty list, nothing will be added to the query string.

Otherwise, this function will take care of inserting a textual representation of your values in the query string, under the same query string parameter name.

You can control how values for your type are turned into text by specifying a ToHttpApiData instance for your type.

Example:

type MyApi = "books" :> QueryParams "authors" Text :> Get '[JSON] [Book]

myApi :: Proxy MyApi
myApi = Proxy

getBooksBy :: [Text] -> ExceptT String IO [Book]
getBooksBy = client myApi host
  where host = BaseUrl Http "localhost" 8080
-- then you can just use "getBooksBy" to query that endpoint.
-- 'getBooksBy []' for all books
-- 'getBooksBy ["Isaac Asimov", "Robert A. Heinlein"]'
--   to get all books by Asimov and Heinlein

(KnownSymbol sym, ToHttpApiData a, HasClient k sublayout) => HasClient * ((:>) * k (QueryParam * sym a) sublayout)

If you use a QueryParam in one of your endpoints in your API, the corresponding querying function will automatically take an additional argument of the type specified by your QueryParam, enclosed in Maybe.

If you give Nothing, nothing will be added to the query string.

If you give a non-Nothing value, this function will take care of inserting a textual representation of this value in the query string.

You can control how values for your type are turned into text by specifying a ToHttpApiData instance for your type.

Example:

type MyApi = "books" :> QueryParam "author" Text :> Get '[JSON] [Book]

myApi :: Proxy MyApi
myApi = Proxy

getBooksBy :: Maybe Text -> ExceptT String IO [Book]
getBooksBy = client myApi host
  where host = BaseUrl Http "localhost" 8080
-- then you can just use "getBooksBy" to query that endpoint.
-- 'getBooksBy Nothing' for all books
-- 'getBooksBy (Just "Isaac Asimov")' to get all books by Isaac Asimov

HasClient k sublayout => HasClient * ((:>) * k HttpVersion sublayout)

Using a HttpVersion combinator in your API doesn't affect the client functions.

(KnownSymbol sym, ToHttpApiData a, HasClient k sublayout) => HasClient * ((:>) * k (Header sym a) sublayout)

If you use a Header in one of your endpoints in your API, the corresponding querying function will automatically take an additional argument of the type specified by your Header, wrapped in Maybe.

That function will take care of encoding this argument as Text in the request headers.

All you need is for your type to have a ToHttpApiData instance.

Example:

newtype Referer = Referer { referrer :: Text }
  deriving (Eq, Show, Generic, FromText, ToHttpApiData)

           -- GET /view-my-referer
type MyApi = "view-my-referer" :> Header "Referer" Referer :> Get '[JSON] Referer

myApi :: Proxy MyApi
myApi = Proxy

viewReferer :: Maybe Referer -> ExceptT String IO Book
viewReferer = client myApi host
  where host = BaseUrl Http "localhost" 8080
-- then you can just use "viewRefer" to query that endpoint
-- specifying Nothing or e.g Just "http://haskell.org/" as arguments

(KnownSymbol capture, ToHttpApiData a, HasClient k sublayout) => HasClient * ((:>) * k (Capture * capture a) sublayout)

If you use a Capture in one of your endpoints in your API, the corresponding querying function will automatically take an additional argument of the type specified by your Capture. That function will take care of inserting a textual representation of this value at the right place in the request path.

You can control how values for this type are turned into text by specifying a ToHttpApiData instance for your type.

Example:

type MyApi = "books" :> Capture "isbn" Text :> Get '[JSON] Book

myApi :: Proxy MyApi
myApi = Proxy

getBook :: Text -> ExceptT String IO Book
getBook = client myApi host manager
  where host = BaseUrl Http "localhost" 8080
-- then you can just use "getBook" to query that endpoint

(KnownSymbol path, HasClient k sublayout) => HasClient * ((:>) Symbol k path sublayout)

Make the querying function append path to the request path.

(BuildHeadersTo ls, ReflectMethod k method) => HasClient * (Verb k * method status cts (Headers ls NoContent))

(MimeUnrender * ct a, BuildHeadersTo ls, ReflectMethod k method, (~) [*] cts' ((:) * ct cts)) => HasClient * (Verb k * method status cts' (Headers ls a))

ReflectMethod k method => HasClient * (Verb k * method status cts NoContent)

(MimeUnrender * ct a, ReflectMethod k method, (~) [*] cts' ((:) * ct cts)) => HasClient * (Verb k * method status cts' a)

mkAuthenticateReq :: AuthClientData a -> (AuthClientData a -> Req -> Req) -> AuthenticateReq a

Handy helper to avoid wrapping datatypes in tuples everywhere.

NOTE: THIS API IS EXPERIMENTAL AND SUBJECT TO CHANGE

data ServantError

Constructors

FailureResponse

Fields

responseStatus :: Status

responseContentType :: MediaType

responseBody :: ByteString

DecodeFailure

Fields

decodeError :: String

responseContentType :: MediaType

responseBody :: ByteString

UnsupportedContentType

Fields

responseContentType :: MediaType

responseBody :: ByteString

InvalidContentTypeHeader

Fields

responseContentTypeHeader :: ByteString

responseBody :: ByteString

ConnectionError

Fields

connectionError :: SomeException

Instances

Show ServantError

Exception ServantError

module Servant.Common.BaseUrl