Safe Haskell	None
Language	GHC2024

Arbiter.Core.Codec

Contents

Column types
Row decoding
Parameter encoding
Job codecs
Cron codecs

Description

Typed encoding and decoding for PostgreSQL queries.

RowCodec - free applicative for decoding result rows. Each backend (postgresql-simple, hasql, orville) interprets it natively.
Params - typed parameter list for query execution.

Both use the same Col GADT, keeping encode and decode types in sync.

Synopsis

data Col a where
- CInt4 :: Col Int32
- CInt8 :: Col Int64
- CText :: Col Text
- CBool :: Col Bool
- CTimestamptz :: Col UTCTime
- CJsonb :: Col Value
- CFloat8 :: Col Double
data NullCol a where
- NotNull :: forall a. Text -> Col a -> NullCol a
- Nullable :: forall a1. Text -> Col a1 -> NullCol (Maybe a1)
type RowCodec = Ap NullCol
col :: Text -> Col a -> RowCodec a
ncol :: Text -> Col a -> RowCodec (Maybe a)
pureVal :: a -> RowCodec a
runCodec :: Applicative f => (forall x. NullCol x -> f x) -> RowCodec a -> f a
codecColumns :: RowCodec a -> [Text]
data ParamType a where
- PScalar :: forall a. Col a -> ParamType a
- PNullable :: forall a1. Col a1 -> ParamType (Maybe a1)
- PArray :: forall a1. Col a1 -> ParamType [a1]
- PNullArray :: forall a1. Col a1 -> ParamType [Maybe a1]
data SomeParam where
- SomeParam :: forall a. ParamType a -> a -> SomeParam
type Params = [SomeParam]
pval :: Col a -> a -> SomeParam
pnul :: Col a -> Maybe a -> SomeParam
parr :: Col a -> [a] -> SomeParam
pnarr :: Col a -> [Maybe a] -> SomeParam
jobRowCodec :: Text -> RowCodec (Job Value Int64 Text UTCTime)
dlqRowCodec :: Text -> RowCodec (Int64, UTCTime, Job Value Int64 Text UTCTime)
countCodec :: RowCodec Int64
statsRowCodec :: RowCodec (Int64, Int64, Maybe Double)
cronScheduleRowCodec :: RowCodec CronScheduleRow

Column types

data Col a where Source #

Scalar PostgreSQL column type. The GADT tag recovers the Haskell type.

Constructors

CInt4 :: Col Int32
CInt8 :: Col Int64
CText :: Col Text
CBool :: Col Bool
CTimestamptz :: Col UTCTime
CJsonb :: Col Value
CFloat8 :: Col Double

data NullCol a where Source #

A named column with nullability. Carries the column name for backends that use name-based decoding (e.g. orville).

Constructors

NotNull :: forall a. Text -> Col a -> NullCol a
Nullable :: forall a1. Text -> Col a1 -> NullCol (Maybe a1)

Row decoding

type RowCodec = Ap NullCol Source #

Free applicative over NullCol. Backends interpret this into their native row parser by pattern-matching on each NullCol.

col :: Text -> Col a -> RowCodec a Source #

A non-nullable column.

ncol :: Text -> Col a -> RowCodec (Maybe a) Source #

A nullable column.

pureVal :: a -> RowCodec a Source #

Inject a pure value (not read from the database).

runCodec :: Applicative f => (forall x. NullCol x -> f x) -> RowCodec a -> f a Source #

Interpret a RowCodec by providing a natural transformation from NullCol to some Applicative.

codecColumns :: RowCodec a -> [Text] Source #

Extract the column names from a codec (in order).

Parameter encoding

data ParamType a where Source #

How a parameter is shaped: scalar, nullable, or array.

Constructors

PScalar :: forall a. Col a -> ParamType a
PNullable :: forall a1. Col a1 -> ParamType (Maybe a1)
PArray :: forall a1. Col a1 -> ParamType [a1]
PNullArray :: forall a1. Col a1 -> ParamType [Maybe a1]

data SomeParam where Source #

An existentially-typed parameter: a ParamType paired with its value.

Constructors

SomeParam :: forall a. ParamType a -> a -> SomeParam

type Params = [SomeParam] Source #

Positional query parameters.

pval :: Col a -> a -> SomeParam Source #

pnul :: Col a -> Maybe a -> SomeParam Source #

parr :: Col a -> [a] -> SomeParam Source #

pnarr :: Col a -> [Maybe a] -> SomeParam Source #

Job codecs

jobRowCodec :: Text -> RowCodec (Job Value Int64 Text UTCTime) Source #

dlqRowCodec :: Text -> RowCodec (Int64, UTCTime, Job Value Int64 Text UTCTime) Source #

countCodec :: RowCodec Int64 Source #

statsRowCodec :: RowCodec (Int64, Int64, Maybe Double) Source #

Cron codecs

cronScheduleRowCodec :: RowCodec CronScheduleRow Source #