b02bcf7 · typeable/postgresql-simple

git.iko.soy/typeable/postgresql-simple

Mention GHC generics support in documentation (#6)

* Mention GHC generics support in documentation

commitb02bcf76e02ddd2890ce0b9ac04467063a8b9c3d authorGabriel Gonzalez <Gabriel439@gmail.com> dateThu 7 Feb 2019, 02:57 (8 years ago) parent466c469

2 files changed+33

compare with master

unifiedsplit

src/Database/PostgreSQL/Simple/FromRow.hs+17 src/Database/PostgreSQL/Simple/ToRow.hs+16

src/Database/PostgreSQL/Simple/FromRow.hs+17

@@ -67,6 +67,23 @@ import GHC.Generics

6767-- in a single row of the query result. Otherwise, a 'ConversionFailed'

6868-- exception will be thrown.

6969--

70+-- You can also derive 'FromRow' for your data type using GHC generics, like

71+-- this:

72+--

73+-- @

74+-- \{-# LANGUAGE DeriveAnyClass \#-}

75+-- \{-# LANGUAGE DeriveGeneric \#-}

76+--

77+-- import "GHC.Generics" ('GHC.Generics.Generic')

78+-- import "Database.PostgreSQL.Simple" ('FromRow')

79+--

80+-- data User = User { name :: String, fileQuota :: Int }

81+-- deriving ('GHC.Generics.Generic', 'FromRow')

82+-- @

83+--

84+-- Note that this only works for product types (e.g. records) and does not

85+-- support sum types or recursive types.

86+--

7087-- Note that 'field' evaluates its result to WHNF, so the caveats listed in

7188-- mysql-simple and very early versions of postgresql-simple no longer apply.

7289-- Instead, look at the caveats associated with user-defined implementations

src/Database/PostgreSQL/Simple/ToRow.hs+16

@@ -30,6 +30,22 @@ import GHC.Generics

3030--

3131-- Instances should use the 'toField' method of the 'ToField' class

3232-- to perform conversion of each element of the collection.

33+--

34+-- You can derive 'ToRow' for your data type using GHC generics, like this:

35+--

36+-- @

37+-- \{-# LANGUAGE DeriveAnyClass \#-}

38+-- \{-# LANGUAGE DeriveGeneric \#-}

39+--

40+-- import "GHC.Generics" ('GHC.Generics.Generic')

41+-- import "Database.PostgreSQL.Simple" ('ToRow')

42+--

43+-- data User = User { name :: String, fileQuota :: Int }

44+-- deriving ('GHC.Generics.Generic', 'ToRow')

45+-- @

46+--

47+-- Note that this only works for product types (e.g. records) and does not

48+-- support sum types or recursive types.

3349class ToRow a where

3450 toRow :: a -> [Action]

3551 default toRow :: (Generic a, GToRow (Rep a)) => a -> [Action]