Safe Haskell	None
Language	Haskell2010

Hasql.Interpolate.Internal.Decoder

Contents

Decoding type classes
Generics

Synopsis

class DecodeValue a where
- decodeValue :: Value a
class DecodeField a where
- decodeField :: NullableOrNot Value a
class DecodeRow a where
- decodeRow :: Row a
class DecodeResult a where
- decodeResult :: Result a
class GDecodeRow a where
- gdecodeRow :: Row (a p)

Decoding type classes

class DecodeValue a where Source #

This type class determines which decoder we will apply to a query field by the type of the result.

Example

Expand

data ThreatLevel = None | Midnight

instance DecodeValue ThreatLevel where
  decodeValue = enum \case
    "none"     -> Just None
    "midnight" -> Just Midnight
    _          -> Nothing

Methods

decodeValue :: Value a Source #

Instances

Instances details

DecodeValue Bool Source #	Parse a postgres `bool` using `bool`
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeValue :: Value Bool Source #
DecodeValue Char Source #	Parse a postgres `char` using `char`
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeValue :: Value Char Source #
DecodeValue Double Source #	Parse a postgres `float8` using `float8`
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeValue :: Value Double Source #
DecodeValue Float Source #	Parse a postgres `float4` using `float4`
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeValue :: Value Float Source #
DecodeValue Int16 Source #	Parse a postgres `int2` using `int2`
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeValue :: Value Int16 Source #
DecodeValue Int32 Source #	Parse a postgres `int4` using `int4`
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeValue :: Value Int32 Source #
DecodeValue Int64 Source #	Parse a postgres `int8` using `int8`
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeValue :: Value Int64 Source #
DecodeValue Scientific Source #	Parse a postgres `numeric` using `numeric`
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeValue :: Value Scientific Source #
DecodeValue Text Source #	Parse a postgres `text` using `text`
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeValue :: Value Text Source #
DecodeValue UTCTime Source #	Parse a postgres `timestamptz` using `timestamptz`
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeValue :: Value UTCTime Source #
DecodeValue UUID Source #	Parse a postgres `uuid` using `uuid`
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeValue :: Value UUID Source #
DecodeValue Day Source #	Parse a postgres `date` using `date`
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeValue :: Value Day Source #
DecodeValue DiffTime Source #	Parse a postgres `interval` using `interval`
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeValue :: Value DiffTime Source #
DecodeValue LocalTime Source #	Parse a postgres `timestamp` using `timestamp`
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeValue :: Value LocalTime Source #
DecodeValue Json Source #	Parse a postgres `json` using `json`
Instance details Defined in Hasql.Interpolate.Internal.Json Methods decodeValue :: Value Json Source #
DecodeValue Jsonb Source #	Parse a postgres `jsonb` using `jsonb`
Instance details Defined in Hasql.Interpolate.Internal.Json Methods decodeValue :: Value Jsonb Source #
DecodeField a => DecodeValue [a] Source #	Parse a postgres `array` using `listArray`
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeValue :: Value [a] Source #
DecodeField a => DecodeValue (Vector a) Source #	Parse a postgres `array` using `vectorArray`
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeValue :: Value (Vector a) Source #
(Generic a, GToComposite (Rep a)) => DecodeValue (CompositeValue a) Source #
Instance details Defined in Hasql.Interpolate.Internal.CompositeValue Methods decodeValue :: Value (CompositeValue a) Source #
FromJSON a => DecodeValue (AsJsonb a) Source #	Parse a postgres `jsonb` to anything that is an instance of `FromJSON`
Instance details Defined in Hasql.Interpolate.Internal.Json Methods decodeValue :: Value (AsJsonb a) Source #
FromJSON a => DecodeValue (AsJson a) Source #	Parse a postgres `json` to anything that is an instance of `FromJSON`
Instance details Defined in Hasql.Interpolate.Internal.Json Methods decodeValue :: Value (AsJson a) Source #

class DecodeField a where Source #

You do not need to define instances for this class; The two instances exported here cover all uses. The class only exists to lift Value to hasql's NullableOrNot GADT.

Methods

decodeField :: NullableOrNot Value a Source #

Instances

Instances details

DecodeValue a => DecodeField a Source #	Overlappable instance for parsing non-nullable values
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeField :: NullableOrNot Value a Source #
DecodeValue a => DecodeField (Maybe a) Source #	Instance for parsing nullable values
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeField :: NullableOrNot Value (Maybe a) Source #

class DecodeRow a where Source #

Determine a row decoder from a Haskell type. Derivable with generics for any product type.

Examples

Expand

A manual instance:

data T = T Int64 Bool Text

instance DecodeRow T where
  decodeRow = T
    $ column decodeField
    * column decodeField
    * column decodeField

A generic instance:

data T
 = T Int64 Bool Text
 deriving stock (Generic)
 deriving anyclass (DecodeRow)

Minimal complete definition

Nothing

Methods

decodeRow :: Row a Source #

default decodeRow :: (Generic a, GDecodeRow (Rep a)) => Row a Source #

Instances

Instances details

DecodeField a => DecodeRow (OneColumn a) Source #	Parse a single column row
Instance details Defined in Hasql.Interpolate.Internal.OneColumn Methods decodeRow :: Row (OneColumn a) Source #
(DecodeField x1, DecodeField x2) => DecodeRow (x1, x2) Source #
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeRow :: Row (x1, x2) Source #
(DecodeField x1, DecodeField x2, DecodeField x3) => DecodeRow (x1, x2, x3) Source #
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeRow :: Row (x1, x2, x3) Source #
(DecodeField x1, DecodeField x2, DecodeField x3, DecodeField x4) => DecodeRow (x1, x2, x3, x4) Source #
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeRow :: Row (x1, x2, x3, x4) Source #
(DecodeField x1, DecodeField x2, DecodeField x3, DecodeField x4, DecodeField x5) => DecodeRow (x1, x2, x3, x4, x5) Source #
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeRow :: Row (x1, x2, x3, x4, x5) Source #
(DecodeField x1, DecodeField x2, DecodeField x3, DecodeField x4, DecodeField x5, DecodeField x6) => DecodeRow (x1, x2, x3, x4, x5, x6) Source #
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeRow :: Row (x1, x2, x3, x4, x5, x6) Source #
(DecodeField x1, DecodeField x2, DecodeField x3, DecodeField x4, DecodeField x5, DecodeField x6, DecodeField x7) => DecodeRow (x1, x2, x3, x4, x5, x6, x7) Source #
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeRow :: Row (x1, x2, x3, x4, x5, x6, x7) Source #
(DecodeField x1, DecodeField x2, DecodeField x3, DecodeField x4, DecodeField x5, DecodeField x6, DecodeField x7, DecodeField x8) => DecodeRow (x1, x2, x3, x4, x5, x6, x7, x8) Source #
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeRow :: Row (x1, x2, x3, x4, x5, x6, x7, x8) Source #

class DecodeResult a where Source #

Determine a result decoder from a Haskell type.

Methods

decodeResult :: Result a Source #

Instances

Instances details

DecodeResult Int64 Source #	Parse the rows affected from the query result, as in an `insert`, `update`, or `delete` statement without a returning clause. (`rowsAffected`)
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeResult :: Result Int64 Source #
DecodeResult () Source #	Ignore the query response (`noResult`)
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeResult :: Result () Source #
DecodeRow a => DecodeResult [a] Source #	Parse any number of rows into a list (`rowList`)
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeResult :: Result [a] Source #
DecodeRow a => DecodeResult (Maybe a) Source #	Parse zero or one rows, throw `UnexpectedAmountOfRows` otherwise. (`rowMaybe`)
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeResult :: Result (Maybe a) Source #
DecodeRow a => DecodeResult (Vector a) Source #	Parse any number of rows into a `Vector` (`rowVector`)
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods decodeResult :: Result (Vector a) Source #
DecodeRow a => DecodeResult (OneRow a) Source #	Parse a single row result, throw `UnexpectedAmountOfRows` otherwise. (`singleRow`)
Instance details Defined in Hasql.Interpolate.Internal.OneRow Methods decodeResult :: Result (OneRow a) Source #

Generics

class GDecodeRow a where Source #

Methods

gdecodeRow :: Row (a p) Source #

Instances

Instances details

DecodeField a => GDecodeRow (K1 i a :: Type -> Type) Source #
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods gdecodeRow :: Row (K1 i a p) Source #
(GDecodeRow a, GDecodeRow b) => GDecodeRow (a :*: b) Source #
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods gdecodeRow :: Row ((a :*: b) p) Source #
GDecodeRow a => GDecodeRow (M1 t i a) Source #
Instance details Defined in Hasql.Interpolate.Internal.Decoder Methods gdecodeRow :: Row (M1 t i a p) Source #