tommyengstrom / servant-flow

Generate javascript client with flow types

servant-flow

Generate Axios clients for Servant APIs with Flow types.

We use a Generic-derivable type class that takes the same Options argument as used in the aeson package, to ensure correspondence with FromJSON/ToJSON instances. The generic instances support records and simple sum types, while arbitrary sums of products are not yet supported unless you provide the instances explicitly.

NOTE: As this is a young package, take reasonable precautions before fully trusting it in production.

Example

This Servant API

data Transformation = ToUpper | ToLower
    deriving (Show, Generic, ToJSON, FromJSON, Flow)

type API = "changeCase"
        :> Capture "transformation" Transformation
        :> QueryParam "maxChars" Int
        :> QueryFlag "fromEnd"
        :> Get '[JSON] Text
    :<|> "user" :> ReqBody '[JSON] Text :> Post '[JSON] Text

leads to the following client code via generateFlowClient (Proxy @API) defaultCodeGenOptions:

// @flow

const axios = require('axios')

function createClient(
    token/* : string */,
    baseURL/* : string */
    ){
    return axios.create({
            headers: {
                Authorization: token
                },
            baseURL: baseURL
            }
        )
    }
module.exports.createClient = createClient

/*::

type Transformation = "ToUpper" | "ToLower"

*/


function getChangeCaseByTransformation(
    client /* : any */,
    transformation /* : Transformation */,
    opts /* : {
        maxChars : ?(number),
        fromEnd : boolean
        } */
    )/* : Promise<{ status: string, data: string }> */{
    return client({
            url: [
                'changeCase',
                encodeURIComponent(transformation.toString())
                ].join('/'),
            method: 'get',
            params: opts
            }
        )
    }
module.exports.getChangeCaseByTransformation = getChangeCaseByTransformation


function postUser(
    client /* : any */,
    data /* : string */
    )/* : Promise<{ status: string, data: string }> */{
    return client({
            url: [
                'user'
                ].join('/'),
            method: 'post',
            data: JSON.stringify(data)
            }
        )
    }
module.exports.postUser = postUser

See either of the two test suites for details.

Run integration tests with

./run-tests