Database.Relational.Query.Projection

This module defines query projection type structure and interfaces.

Projection data structure and interface

data Projection c t

Phantom typed projection. Projected into Haskell record type t.

Instances

ProjectableApplicative (Projection c)

Compose record type Projection using applicative style.

ProjectableFunctor (Projection c)

Compose seed of record type Projection.

ProjectableMaybe (Projection c)

Control phantom Maybe type in projection type Projection.

ProjectableShowSql (Projection c)

Unsafely get SQL term from Proejction.

SqlProjectable (Projection OverWindow)

Unsafely make Projection from SQL terms.

SqlProjectable (Projection Aggregated)

Unsafely make Projection from SQL terms.

SqlProjectable (Projection Flat)

Unsafely make Projection from SQL terms.

width :: Projection c r -> Int

Width of Projection.

columns

Arguments

:: Projection c r

Source Projection

-> [ColumnSQL]

Result SQL string list

Get column SQL string list of projection.

untype :: Projection c r -> UntypedProjection

Unsafely get untyped projection.

unsafeFromColumns

Arguments

:: [ColumnSQL]

SQL string list specifies columns

-> Projection c r

Result Projection

Unsafely generate Projection from SQL string list.

unsafeFromQualifiedSubQuery :: Qualified SubQuery -> Projection c t

Unsafely generate Projection from qualified (joined) subquery.

unsafeFromScalarSubQuery :: SubQuery -> Projection c t

Unsafely generate Projection from scalar subquery.

unsafeFromTable :: Table r -> Projection c r

Unsafely generate unqualified Projection from Table.

Projections

pi

Arguments

:: Projection c a

Source Projection

-> Pi a b

Projection path

-> Projection c b

Narrower Projection

Trace projection path to get narrower Projection.

piMaybe

Arguments

:: Projection c (Maybe a)

Source Projection. Maybe type

-> Pi a b

Projection path

-> Projection c (Maybe b)

Narrower Projection. Maybe type result

Trace projection path to get narrower Projection. From Maybe type to Maybe type.

piMaybe'

Arguments

:: Projection c (Maybe a)

Source Projection. Maybe type

-> Pi a (Maybe b)

Projection path. Maybe type leaf

-> Projection c (Maybe b)

Narrower Projection. Maybe type result

Trace projection path to get narrower Projection. From Maybe type to Maybe type. Leaf type of projection path is Maybe.

flattenMaybe :: Projection c (Maybe (Maybe a)) -> Projection c (Maybe a)

Composite nested Maybe on projection phantom type.

just :: Projection c r -> Projection c (Maybe r)

Cast into Maybe on projection phantom type.

unsafeToAggregated :: Projection Flat r -> Projection Aggregated r

Unsafely lift to aggregated context.

unsafeToFlat :: Projection Aggregated r -> Projection Flat r

Unsafely down to flat context.

unsafeChangeContext :: Projection c r -> Projection c' r

Unsafely cast context type tag.

unsafeShowSqlNotNullMaybeProjection :: HasColumnConstraint NotNull r => Projection c (Maybe r) -> String

Unsafely get SQL string expression of not null key projection.

pfmap :: ProductConstructor (a -> b) => (a -> b) -> Projection c a -> Projection c b

Projectable fmap of Projection type.

pap :: Projection c (a -> b) -> Projection c a -> Projection c b

Projectable ap of Projection type.

List Projection

data ListProjection p t

Projection type for row list.

list :: [p t] -> ListProjection p t

Make row list projection from Projection list.

unsafeListProjectionFromSubQuery :: SubQuery -> ListProjection p t

Make row list projection from SubQuery.

unsafeShowSqlListProjection :: (p t -> String) -> ListProjection p t -> String

Map projection show operatoions and concatinate to single SQL expression.