Database.Record.FromSql

This module defines interfaces from list of database value type into Haskell type.

Conversion from list of database value type into record type

data RecordFromSql q a

RecordFromSql q a is data-type wrapping function to convert from list of database value type (to receive from database) [q] into Haskell type a

This structure is similar to parser. While running RecordFromSql behavior is the same as non-fail-able parser which parse list of database value type [q] stream.

So, RecordFromSql q is Monad and Applicative instance like parser monad. When, you have data constructor and objects like below.

  data MyRecord = MyRecord Foo Bar Baz

  foo :: RecordFromSql SqlValue Foo
  foo =  ...
  bar :: RecordFromSql SqlValue Bar
  bar =  ...
  baz :: RecordFromSql SqlValue Bar
  baz =  ...

You can get composed RecordFromSql like below.

  myRecord :: RecordFromSql SqlValue MyRecord
  myRecord =  MyRecord <$> foo <*> bar <*> baz

Instances

Monad (RecordFromSql q)

Monad instance like parser Monad.

Methods

(>>=) :: RecordFromSql q a -> (a -> RecordFromSql q b) -> RecordFromSql q b

(>>) :: RecordFromSql q a -> RecordFromSql q b -> RecordFromSql q b

return :: a -> RecordFromSql q a

fail :: String -> RecordFromSql q a

Functor (RecordFromSql q)

Derived Functor instance from Monad instance

Methods

fmap :: (a -> b) -> RecordFromSql q a -> RecordFromSql q b

(<$) :: a -> RecordFromSql q b -> RecordFromSql q a

Applicative (RecordFromSql q)

Derived Applicative instance from Monad instance

Methods

pure :: a -> RecordFromSql q a

(<*>) :: RecordFromSql q (a -> b) -> RecordFromSql q a -> RecordFromSql q b

(*>) :: RecordFromSql q a -> RecordFromSql q b -> RecordFromSql q b

(<*) :: RecordFromSql q a -> RecordFromSql q b -> RecordFromSql q a

runTakeRecord

Arguments

:: RecordFromSql q a

parser function object which has capability to convert

-> [q]

list of database value type

-> (a, [q])

Haskell type and rest of list

Run RecordFromSql parser function object. Convert from list of database value type [q] into Haskell type a and rest of list [q].

runToRecord

Arguments

:: RecordFromSql q a

parser function object which has capability to convert

-> [q]

list of database value type

-> a

Haskell type

Run RecordFromSql parser function object. Convert from list of database value type [q] into Haskell type a.

createRecordFromSql

Arguments

:: ([q] -> (a, [q]))

Convert function body

-> RecordFromSql q a

Result parser function object

Axiom of RecordFromSql for database value type q and Haskell type a

(<&>) :: RecordFromSql q a -> RecordFromSql q b -> RecordFromSql q (a, b) infixl 4

Derivation rule of RecordFromSql parser function object for Haskell tuple (,) type.

maybeRecord :: PersistableType q => RecordFromSql q a -> ColumnConstraint NotNull a -> RecordFromSql q (Maybe a)

Derivation rule of RecordFromSql parser function object for Haskell Maybe type.

Derivation rules of RecordFromSql conversion

class FromSql q a where

FromSql q a is implicit rule to derive RecordFromSql q a record parser function against type a.

Generic programming (https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts.html#generic-programming) with default signature is available for FromSql class, so you can make instance like below:

  {-# LANGUAGE DeriveGeneric #-}
  import GHC.Generics (Generic)
  import Database.HDBC (SqlValue)
  --
  data Foo = Foo { ... } deriving Generic
  instance FromSql SqlValue Foo

Methods

recordFromSql :: RecordFromSql q a

RecordFromSql q a record parser function.

recordFromSql :: (Generic a, GFromSql q (Rep a)) => RecordFromSql q a

RecordFromSql q a record parser function.

Instances

FromSql q ()

Implicit derivation rule of RecordFromSql parser function object which can convert from empty list of database value type [q] into Haskell unit () type.

Methods

recordFromSql :: RecordFromSql q ()

(HasColumnConstraint NotNull a, FromSql q a, PersistableType q) => FromSql q (Maybe a)

Implicit derivation rule of RecordFromSql parser function object which can convert from list of database value type [q] into Haskell Maybe type.

Methods

recordFromSql :: RecordFromSql q (Maybe a)

takeRecord :: FromSql q a => [q] -> (a, [q])

Run implicit RecordFromSql parser function object. Convert from list of database value type [q] into haskell type a and rest of list [q].

toRecord :: FromSql q a => [q] -> a

Run implicit RecordFromSql parser function object. Convert from list of database value type [q] into haskell type a.

valueRecordFromSql :: (q -> a) -> RecordFromSql q a

Derivation rule of RecordFromSql parser function object for value convert function.