deriving-aeson 0 → 0.1

raw patch · 4 files changed

+98/−5 lines, 4 filesPVP ok

version bump matches the API change (PVP)

API changes (from Hackage documentation)

Files

• README.md +70/−0
• deriving-aeson.cabal +5/−3
• src/Deriving/Aeson/Stock.hs +21/−0
• tests/test.hs +2/−2

@@ -0,0 +1,70 @@+deriving-aeson+====++[![Hackage](https://img.shields.io/hackage/v/deriving-aeson.svg)](https://hackage.haskell.org/package/deriving-aeson)+![Haskell CI](https://github.com/fumieval/deriving-aeson/workflows/Haskell%20CI/badge.svg)+[![Discord](https://img.shields.io/discord/664807830116892674?color=%237095ec&label=Discord&style=plastic)](https://discord.gg/DG93Tgs)++This package provides a newtype wrapper where you can customise+[aeson](https://hackage,haskell.org/package/aeson)'s generic methods using a+type-level interface, which synergises well with DerivingVia.++```haskell+{-# LANGUAGE DerivingVia, DataKinds, DeriveGeneric #-}+import Data.Aeson+import Deriving.Aeson+import qualified Data.ByteString.Lazy.Char8 as BL++data User = User+  { userId :: Int+  , userName :: String+  , userAPIToken :: Maybe String+  } deriving Generic+  deriving (FromJSON, ToJSON)+  via CustomJSON '[OmitNothingFields, FieldLabelModifier (StripPrefix "user", CamelToSnake)] User++testData :: [User]+testData = [User 42 "Alice" Nothing, User 43 "Bob" (Just "xyz")]++main = BL.putStrLn $ encode testData+-- [{"name":"Alice","id":42},{"api_token":"xyz","name":"Bob","id":43}]+```++`Deriving.Aeson.Stock` contains some aliases for even less boilerplates.++* `Prefixed str` = `CustomJSON '[FieldLabelModifier (StripPrefix str)]`+* `PrefixedSnake str` = `CustomJSON '[FieldLabelModifier (StripPrefix str, CamelToSnake)]`+* `Snake` = `CustomJSON '[FieldLabelModifier (StripPrefix str, CamelToSnake)]`++How it works+----++The wrapper type has a phantom type parameter `t`, a type-level builder of an [Option](http://hackage.haskell.org/package/aeson-1.4.6.0/docs/Data-Aeson.html#t:Options).+Type-level primitives are reduced to one `Option` by the `AesonOptions` class.++```haskell+newtype CustomJSON t a = CustomJSON { unCustomJSON :: a }++class AesonOptions xs where+  aesonOptions :: Options++instance AesonOptions xs => AesonOptions (OmitNothingFields ': xs) where+  aesonOptions = (aesonOptions @xs) { omitNothingFields = True }++...+```++You can use any (static) function for name modification by adding an instance of `StringModifier`.++```haskell+data ToLower+instance StringModifier ToLower where+  getStringModifier "" = ""+  getStringModifier (c : xs) = toLower c : xs+```++Previous studies+----++* [Type-driven safe derivation of ToJSON and FromJSON, using DerivingVia in GHC 8.6 and some type-level hacks](https://gist.github.com/konn/27c00f784dd883ec2b90eab8bc84a81d)+* [Strip prefices from JSON representation](https://gist.github.com/fumieval/5c89205d418d5f9cafac801afbe94969)

@@ -1,6 +1,6 @@ cabal-version:       2.4 name:                deriving-aeson-version:             0+version:             0.1 synopsis:            Type driven generic aeson instance customisation description:         This package provides a newtype wrapper with   FromJSON/ToJSON instances customisable via a phantom type parameter.@@ -12,10 +12,12 @@ maintainer:          fumiexcel@gmail.com copyright:           Copyright (c) 2020 Fumiaki Kinoshita category:            JSON, Generics-extra-source-files:  CHANGELOG.md+extra-source-files:  CHANGELOG.md, README.md  library-  exposed-modules:     Deriving.Aeson+  exposed-modules:+    Deriving.Aeson+    Deriving.Aeson.Stock   build-depends:       base >= 4.12 && <5, aeson   hs-source-dirs: src   default-language:    Haskell2010

@@ -0,0 +1,21 @@+{-# LANGUAGE DataKinds #-}++module Deriving.Aeson.Stock+  ( Prefixed+  , PrefixedSnake+  , Snake+  -- * Reexports+  , FromJSON+  , ToJSON+  , Generic) where++import Deriving.Aeson++-- | Field names are prefixed by @str@; strip them from JSON representation+type Prefixed str = CustomJSON '[FieldLabelModifier (StripPrefix str)]++-- | Strip @str@ prefices and convert from CamelCase to snake_case+type PrefixedSnake str = CustomJSON '[FieldLabelModifier (StripPrefix str, CamelToSnake)]++-- | Convert from CamelCase to snake_case+type Snake = CustomJSON '[FieldLabelModifier CamelToSnake]

@@ -3,8 +3,8 @@ module Main where  import Data.Aeson-import qualified Data.ByteString.Lazy.Char8 as BL import Deriving.Aeson+import qualified Data.ByteString.Lazy.Char8 as BL  data User = User   { userId :: Int@@ -17,4 +17,4 @@ testData :: [User] testData = [User 42 "Alice" Nothing, User 43 "Bob" (Just "xyz")] -main = BL.putStrLn $ encode $ testData+main = BL.putStrLn $ encode testData