https://github.com/cdepillabout/envelope

Envelope type used to return responses from a JSON API for Haskell
https://github.com/cdepillabout/envelope

envelope haskell json json-api response wrapper

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Envelope type used to return responses from a JSON API for Haskell

• Host: GitHub
• URL: https://github.com/cdepillabout/envelope
• Owner: cdepillabout
• License: bsd-3-clause
• Created: 2016-04-06T07:24:27.000Z (over 8 years ago)
• Default Branch: master
• Last Pushed: 2017-04-19T06:25:10.000Z (over 7 years ago)
• Last Synced: 2024-04-24T22:02:39.542Z (8 months ago)
• Topics: envelope, haskell, json, json-api, response, wrapper
• Language: Haskell
• Homepage: https://hackage.haskell.org/package/envelope
• Size: 18.6 KB
• Stars: 4
• Watchers: 4
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        

Web.Envelope

============

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[![Stackage LTS](http://stackage.org/package/envelope/badge/lts)](http://stackage.org/lts/package/envelope)

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![BSD3 license](https://img.shields.io/badge/license-BSD3-blue.svg)

This module exports an `Envelope` type that can be used to wrap reponses from a JSON REST API.  It provides a successful `Success` response, and a failure `Err` response.

Here is a small demonstration of returning a success response:

```haskell

>>> import qualified Data.ByteString.Lazy.Char8 as C8

>>> import Data.Aeson (decode, encode)

>>> let successEnvelope = toSuccessEnvelope 3 :: Envelope Text Int

>>> C8.putStrLn $ encode successEnvelope

{"data":3}

>>> decode "{\"data\":3}" :: Maybe (Envelope Text Int)

Just (EnvelopeSuccess (Success 3))

```

Your data gets wrapped in an object with a single `"data"` field:

```json

{

    "data": 3

}

```

Now lets look at how an error response is encoded and decoded.  It is encoded

as an object with two members: @\"extra\"@ and @\"error\"@.

```haskell

>>> let errorEnvelope = toErrEnvelope "DB_ERROR" "there was an error in the database" :: Envelope String Int

>>> C8.putStrLn $ encode errorEnvelope

{"extra":"there was an error in the database","error":"DB_ERROR"}

>>> decode "{\"extra\":\"there was an error in the database\",\"error\":\"DB_ERROR\"}" :: Maybe (Envelope String Int)

Just (EnvelopeErr (Err {errErr = "DB_ERROR", errExtra = Just "there was an error in the database"}))

```

Your error type and extra message get wrapped in an object:

```json

{

    "extra": "there was an error in the database",

    "error": "DB_ERROR"

}

```