Merge pull request #46 from anton-k/th-derving-request-inputs

Th derving request inputs

docs/src/09-reference.md

@@ -359,3 +359,44 @@ getRespOrValue :: RespOr media BL.ByteString a -> Either BL.ByteString a
 
 To unwrap `Resp` from response.
 
+## Other utils
+
+### deriving helpers
+
+Sometimes we need to derive too many types at once
+to use the type in the library. There are helpers to reduce deriving boiler-plate:
+
+
+```haskell
+deriveParam ''FooType          -- derives parameter instances for a FooType
+deriveNewtypeParam ''FooType   -- derives parameter instances for a newtype FooType
+
+deriveBody ''FooType          -- derives request body instances for a FooType
+deriveNewtypeBody ''FooType   -- derives request body instances for a newtype FooType
+
+deriveHttp ''FooType          -- derives both parameter and request body instances for a FooType
+deriveNewtypeHttp ''FooType   -- derives both parameterrequest body instances for a newtype FooType
+
+mapDerive fun [''Foo, ''Bar]  -- maps deriving over several types
+```
+We need to activate `TemplateHaskell`, `StandaloneDeriving`, `DerivingStrategies`, `DeriveGeneric` extensions to use it.
+
+Also note that for this to work all types should be in scope. 
+So it better to define derivings at the bottom of the module which is dedicated to types.
+
+Also type should not have generic arguments for deriving to work.
+If it does we have to declare the types manyally. For example:
+
+```haskell
+data Timed a = Timed
+  { from :: Day
+  , content :: [a]
+  }
+  deriving (Generic, ToJSON, FromJSON)
+
+deriving instance (ToSchema a) => ToSchema (Timed a)
+```
+
+The data type `Timed` has an argument and we have to define the instance 
+explicitly.
+

examples/mig-example-apps/Html/src/Types.hs

@@ -11,12 +11,10 @@ module Types (
   SubmitBlogPost (..),
 ) where
 
-import Data.Aeson (FromJSON)
 import Data.Text (Text)
 import Data.Time
 import Data.UUID
-import GHC.Generics
-import Mig (FromForm, FromHttpApiData, ToHttpApiData, ToParamSchema, ToSchema)
+import Mig (deriveForm, deriveNewtypeParam, mapDerive)
 
 -- | Web-page for our site
 newtype Page a = Page a
@@ -32,7 +30,6 @@ newtype ListPosts = ListPosts [BlogPost]
 
 -- | Blog post id
 newtype BlogPostId = BlogPostId {unBlogPostId :: UUID}
-  deriving newtype (FromHttpApiData, ToHttpApiData, Eq, Show, FromJSON, ToParamSchema)
 
 data BlogPostView
   = ViewBlogPost BlogPost
@@ -57,4 +54,9 @@ data SubmitBlogPost = SubmitBlogPost
   { title :: Text
   , content :: Text
   }
-  deriving (Generic, FromForm, ToSchema)
+
+--------------------------------------------
+-- derivings
+
+mapDerive deriveNewtypeParam [''BlogPostId]
+deriveForm ''SubmitBlogPost

examples/mig-example-apps/JsonApi/Types.hs

@@ -24,15 +24,12 @@ data User = User
   { name :: Text
   , pass :: Text
   }
-  deriving (Generic, ToJSON, FromJSON, ToSchema)
 
 newtype AuthToken = AuthToken Text
-  deriving newtype (ToJSON, FromJSON, FromHttpApiData, Eq, Ord, Show, ToParamSchema, ToSchema)
 
 -- weather domain
 
 newtype DayInterval = DayInterval Int
-  deriving newtype (ToJSON, FromJSON, FromHttpApiData, ToParamSchema)
 
 data Timed a = Timed
   { from :: Day
@@ -43,20 +40,22 @@ data Timed a = Timed
 deriving instance (ToSchema a) => ToSchema (Timed a)
 
 newtype Location = Location Text
-  deriving newtype (ToJSON, FromJSON, FromHttpApiData, Eq, Ord, Show, ToParamSchema, ToSchema)
 
 data WeatherData = WeatherData
   { temperature :: Int
   , windSpeed :: Int
   , sunRainRatio :: Int
   , pressure :: Int
   }
-  deriving (Generic, ToJSON, FromJSON, ToSchema)
 
 -- | Update weather data
 data UpdateData = UpdateData
   { day :: Day
   , location :: Location
   , content :: WeatherData
   }
-  deriving (Generic, ToJSON, FromJSON, ToSchema)
+
+-- derivings
+
+mapDerive deriveNewtypeHttp [''AuthToken, ''DayInterval, ''Location]
+mapDerive deriveBody [''User, ''WeatherData, ''UpdateData]