servant-elm: Automatically derive Elm functions to query servant webservices.

[ bsd3, library, web ] [ Propose Tags ]

Please see README.md


[Skip to Readme]
Versions [faq] 0.1.0.0, 0.1.0.1, 0.1.0.2, 0.2.0.0, 0.3.0.0, 0.3.0.1, 0.4.0.0, 0.4.0.1, 0.5.0.0, 0.6.0.0, 0.6.0.1, 0.6.0.2, 0.6.1, 0.7.0, 0.7.1
Change log CHANGELOG.md
Dependencies aeson (>=0.9), base (>=4.7 && <5), directory, elm-bridge (>=0.4), lens, servant (>=0.8), servant-elm, servant-foreign (>=0.8), text, wl-pprint-text [details]
License BSD-3-Clause
Copyright 2015-2016 Matt Bray
Author Matt Bray
Maintainer mattjbray@gmail.com
Category Web
Home page http://github.com/mattjbray/servant-elm#readme
Source repo head: git clone https://github.com/mattjbray/servant-elm
Uploaded by k_bx at Tue May 28 13:31:45 UTC 2019
Distributions LTSHaskell:0.5.0.0, NixOS:0.7.1, Stackage:0.5.0.0
Executables readme-example, giphy-example, e2e-tests-example, books-example
Downloads 3661 total (371 in the last 30 days)
Rating (no votes yet) [estimated by rule of succession]
Your Rating
  • λ
  • λ
  • λ
Status Hackage Matrix CI
Docs available [build log]
Last success reported on 2019-05-28 [all 1 reports]

Modules

[Index] [Quick Jump]

Flags

NameDescriptionDefaultType
examples

Build the example programs.

DisabledAutomatic
integration

Build the integration tests (requires an Elm installation).

DisabledAutomatic

Use -f <flag> to enable a flag, or -f -<flag> to disable that flag. More info

Downloads

Maintainer's Corner

For package maintainers and hackage trustees


Readme for servant-elm-0.6.0.0

[back to package description]

Servant Elm

Build Status

Generate Elm functions to query your Servant API!

Elm type generation coutesy of krisajenkins/elm-export.

Installation

Servant Elm is available on Hackage.

Example

First, some language pragmas and imports.

{-# LANGUAGE DataKinds         #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TemplateHaskell   #-}
{-# LANGUAGE TypeOperators     #-}

import           Elm.Derive   (defaultOptions, deriveBoth)

import           Servant.API  ((:>), Capture, Get, JSON)
import           Servant.Elm  (DefineElm (DefineElm), Proxy (Proxy), defElmImports, defElmOptions,
                               generateElmModuleWith)

We have some Haskell-defined types and our Servant API.

data Book = Book
    { name :: String
    }

deriveBoth defaultOptions ''Book

type BooksApi = "books" :> Capture "bookId" Int :> Get '[JSON] Book

Now we can generate Elm functions to query the API:

main :: IO ()
main =
  generateElmModuleWith
    defElmOptions
    [ "Generated"
    , "MyApi"
    ]
    defElmImports
    "my-elm-dir"
    [ DefineElm (Proxy :: Proxy Book)
    ]
    (Proxy :: Proxy BooksApi)

Let's save this as example.hs and run it:

$ stack runghc example.hs
Writing: my-elm-dir/Generated/MyApi.elm
$

Here's what was generated:

module Generated.MyApi exposing(..)

import Json.Decode
import Json.Encode exposing (Value)
-- The following module comes from bartavelle/json-helpers
import Json.Helpers exposing (..)
import Dict exposing (Dict)
import Set
import Http
import String
import Url.Builder

maybeBoolToIntStr : Maybe Bool -> String
maybeBoolToIntStr mx =
  case mx of
    Nothing -> ""
    Just True -> "1"
    Just False -> "0"

type alias Book  =
   { name: String
   }

jsonDecBook : Json.Decode.Decoder ( Book )
jsonDecBook =
   Json.Decode.succeed (\pname -> {name = pname})
   |> required "name" (Json.Decode.string)

jsonEncBook : Book -> Value
jsonEncBook  val =
   Json.Encode.object
   [ ("name", Json.Encode.string val.name)
   ]


getBooksByBookId : Int -> Http.Request Book
getBooksByBookId capture_bookId =
    let
        params =
            List.filterMap identity
            (List.concat
                [])
    in
        Http.request
            { method =
                "GET"
            , headers =
                []
            , url =
                Url.Builder.absolute
                    [ "books"
                    , capture_bookId |> String.fromInt
                    ]
                    params
            , body =
                Http.emptyBody
            , expect =
                Http.expectJson <| jsonDecBook
            , timeout =
                Nothing
            , withCredentials =
                False
            }

See examples for a complete usage example, or take a look at mattjbray/servant-elm-example-app for an example project using this library.

Development

$ git clone https://github.com/mattjbray/servant-elm.git
$ cd servant-elm
$ stack test
$ stack test --flag servant-elm:integration

To build all examples:

$ make examples

To run an example:

$ cd examples/e2e-tests
$ elm-reactor
# Open http://localhost:8000/elm/Main.elm