SpockでPOSTリクエストを受け付けてみる

0_example.hs

$ curl -XPOST -d'name=Alice' -d'age=15' http://localhost:8080/person
Person {name = "Alice", age = 15}

$ curl -XPOST -d'name=Bob' -d'age=16' http://localhost:8080/person
Person {name = "Bob", age = 16}

$ curl -XPOST -d'name=Carol' -d'age=abc' http://localhost:8080/person
Bad Request.

$ curl http://localhost:8080/person
Person {name = "Bob", age = 16}
Person {name = "Alice", age = 15}

1_Main.hs

{-# LANGUAGE OverloadedStrings #-}
module Main where

import Control.Monad.IO.Class (liftIO)
import Data.IORef
import Data.List (intercalate)
import qualified Data.Text as Text
import Network.HTTP.Types (status201, status400)
import Web.Spock.Safe

data Person = Person
    { name :: String
    , age  :: Int
    } deriving Show

main :: IO ()
main = do
    personsRef <- newIORef []
    runSpock 8080 $ spockT id $ do
        -- GET  /person
        get  "person" $ do
            persons <- liftIO $ readIORef personsRef
            text . Text.pack . intercalate "\n" . map show $ persons
        -- POST /person
        post "person" $ do
            maybeName <- param "name"
            maybeAge  <- param "age"
            case Person <$> maybeName <*> maybeAge of
              Nothing     -> setStatus status400 >> text "Bad Request."
              Just person -> do
                  liftIO $ modifyIORef personsRef (person:)
                  setStatus status201
                  text . Text.pack $ show person

2_spock-post.cabal

name:                spock-post
version:             0.1.0.0
build-type:          Simple
cabal-version:       >=1.10

executable app
  main-is:             Main.hs
  ghc-options:         -threaded -rtsopts -with-rtsopts=-N
  build-depends:       base
                     , text
                     , transformers
                     , http-types
                     , Spock
  default-language:    Haskell2010

3_stack.yaml

resolver: lts-5.12
packages:
- '.'
extra-deps: []
flags: {}
extra-package-dbs: []