Safe Haskell	None
Language	Haskell2010

Opaleye.Column

Contents

Column
Working with NULL
Unsafe operations
Entire module

Description

Functions for working directly with Columns.

Please note that numeric Column types are instances of Num, so you can use *, /, +, - on them.

Synopsis

`Column`

data Column pgType Source #

A column of a Query, of type pgType. For example Column PGInt4 is an int4 column and a Column PGText is a text column.

Do not use the Show instance of Column. It will be deprecated in version 0.6.

Instances

Default Constant Bool (Column PGBool) #
Methods def :: Constant Bool (Column PGBool) #
Default Constant Double (Column PGFloat8) #
Methods def :: Constant Double (Column PGFloat8) #
Default Constant Int (Column PGInt4) #
Methods def :: Constant Int (Column PGInt4) #
Default Constant Int32 (Column PGInt4) #
Methods def :: Constant Int32 (Column PGInt4) #
Default Constant Int64 (Column PGInt8) #
Methods def :: Constant Int64 (Column PGInt8) #
Default Constant ByteString (Column PGJsonb) #
Methods def :: Constant ByteString (Column PGJsonb) #
Default Constant ByteString (Column PGJson) #
Methods def :: Constant ByteString (Column PGJson) #
Default Constant ByteString (Column PGBytea) #
Methods def :: Constant ByteString (Column PGBytea) #
Default Constant ByteString (Column PGJsonb) #
Methods def :: Constant ByteString (Column PGJsonb) #
Default Constant ByteString (Column PGJson) #
Methods def :: Constant ByteString (Column PGJson) #
Default Constant ByteString (Column PGBytea) #
Methods def :: Constant ByteString (Column PGBytea) #
Default Constant String (Column PGText) #
Methods def :: Constant String (Column PGText) #
Default Constant Text (Column PGText) #
Methods def :: Constant Text (Column PGText) #
Default Constant UTCTime (Column PGTimestamptz) #
Methods def :: Constant UTCTime (Column PGTimestamptz) #
Default Constant Value (Column PGJsonb) #
Methods def :: Constant Value (Column PGJsonb) #
Default Constant Value (Column PGJson) #
Methods def :: Constant Value (Column PGJson) #
Default Constant Text (Column PGText) #
Methods def :: Constant Text (Column PGText) #
Default Constant LocalTime (Column PGTimestamp) #
Methods def :: Constant LocalTime (Column PGTimestamp) #
Default Constant TimeOfDay (Column PGTime) #
Methods def :: Constant TimeOfDay (Column PGTime) #
Default Constant Day (Column PGDate) #
Methods def :: Constant Day (Column PGDate) #
Default Constant UUID (Column PGUuid) #
Methods def :: Constant UUID (Column PGUuid) #
Default ViewColumnMaker String (Column a) #
Methods def :: ViewColumnMaker String (Column a) #
Default RelExprMaker String (Column a) #
Methods def :: RelExprMaker String (Column a) #
QueryRunnerColumnDefault a b => Default QueryRunner (Column a) b #
Methods def :: QueryRunner (Column a) b #
(Default Constant a (Column b), IsSqlType b) => Default Constant [a] (Column (PGArray b)) #
Methods def :: Constant [a] (Column (PGArray b)) #
Default Constant haskell (Column sql) => Default Constant (Maybe haskell) (Maybe (Column sql)) #
Methods def :: Constant (Maybe haskell) (Maybe (Column sql)) #
Default Constant haskell (Column sql) => Default Constant (Maybe haskell) (Column (Nullable sql)) #
Methods def :: Constant (Maybe haskell) (Column (Nullable sql)) #
Default Constant (CI Text) (Column PGCitext) #
Methods def :: Constant (CI Text) (Column PGCitext) #
Default Constant (CI Text) (Column PGCitext) #
Methods def :: Constant (CI Text) (Column PGCitext) #
Default Constant (PGRange Int) (Column (PGRange PGInt4)) #
Methods def :: Constant (PGRange Int) (Column (PGRange PGInt4)) #
Default Constant (PGRange Int64) (Column (PGRange PGInt8)) #
Methods def :: Constant (PGRange Int64) (Column (PGRange PGInt8)) #
Default Constant (PGRange UTCTime) (Column (PGRange PGTimestamptz)) #
Methods def :: Constant (PGRange UTCTime) (Column (PGRange PGTimestamptz)) #
Default Constant (PGRange LocalTime) (Column (PGRange PGTimestamp)) #
Methods def :: Constant (PGRange LocalTime) (Column (PGRange PGTimestamp)) #
Default Constant (PGRange Day) (Column (PGRange PGDate)) #
Methods def :: Constant (PGRange Day) (Column (PGRange PGDate)) #
Default ColumnMaker (Column a) (Column a) #
Methods def :: ColumnMaker (Column a) (Column a) #
Default Unpackspec (Column a) (Column a) #
Methods def :: Unpackspec (Column a) (Column a) #
Default Binaryspec (Column a) (Column a) #
Methods def :: Binaryspec (Column a) (Column a) #
Default NullMaker (Column a) (Column (Nullable a)) #
Methods def :: NullMaker (Column a) (Column (Nullable a)) #
Default NullMaker (Column (Nullable a)) (Column (Nullable a)) #
Methods def :: NullMaker (Column (Nullable a)) (Column (Nullable a)) #
Default IfPP (Column a) (Column a) #
Methods def :: IfPP (Column a) (Column a) #
Default EqPP (Column a) (Column a) #
Methods def :: EqPP (Column a) (Column a) #
Default Valuesspec (Column a) (Column a) #
Methods def :: Valuesspec (Column a) (Column a) #
Default Distinctspec (Column a) (Column a) #
Methods def :: Distinctspec (Column a) (Column a) #
(PGNum a, PGFractional a) => Fractional (Column a) Source #
Methods (/) :: Column a -> Column a -> Column a # recip :: Column a -> Column a # fromRational :: Rational -> Column a #
PGNum a => Num (Column a) Source #
Methods (+) :: Column a -> Column a -> Column a # (-) :: Column a -> Column a -> Column a # (*) :: Column a -> Column a -> Column a # negate :: Column a -> Column a # abs :: Column a -> Column a # signum :: Column a -> Column a # fromInteger :: Integer -> Column a #
Show (Column pgType) Source #
Methods showsPrec :: Int -> Column pgType -> ShowS # show :: Column pgType -> String # showList :: [Column pgType] -> ShowS #
PGString a => IsString (Column a) Source #
Methods fromString :: String -> Column a #

Working with `NULL`

data Nullable a Source #

Only used within a Column, to indicate that it can be NULL. For example, a Column (Nullable PGText) can be NULL but a Column PGText cannot.

Instances

Default Constant haskell (Column sql) => Default Constant (Maybe haskell) (Column (Nullable sql)) #
Methods def :: Constant (Maybe haskell) (Column (Nullable sql)) #
Default NullMaker (Column a) (Column (Nullable a)) #
Methods def :: NullMaker (Column a) (Column (Nullable a)) #
Default NullMaker (Column (Nullable a)) (Column (Nullable a)) #
Methods def :: NullMaker (Column (Nullable a)) (Column (Nullable a)) #
IsSqlType a => IsSqlType (Nullable a) Source #
Methods showPGType :: proxy (Nullable a) -> String Source # showSqlType :: proxy (Nullable a) -> String Source #
PGOrd a => PGOrd (Nullable a) Source #

QueryRunnerColumnDefault a b => QueryRunnerColumnDefault (Nullable a) (Maybe b) Source #
Methods queryRunnerColumnDefault :: QueryRunnerColumn (Nullable a) (Maybe b) Source #

null :: Column (Nullable a) Source #

A NULL of any type

isNull :: Column (Nullable a) -> Column PGBool Source #

TRUE if the value of the column is NULL, FALSE otherwise.

matchNullable :: Column b -> (Column a -> Column b) -> Column (Nullable a) -> Column b Source #

If the Column (Nullable a) is NULL then return the Column b otherwise map the underlying Column a using the provided function.

The Opaleye equivalent of maybe.

fromNullable :: Column a -> Column (Nullable a) -> Column a Source #

If the Column (Nullable a) is NULL then return the provided Column a otherwise return the underlying Column a.

The Opaleye equivalent of fromMaybe.

toNullable :: Column a -> Column (Nullable a) Source #

Treat a column as though it were nullable. This is always safe.

The Opaleye equivalent of Just.

maybeToNullable :: Maybe (Column a) -> Column (Nullable a) Source #

If the argument is Nothing return NULL otherwise return the provided value coerced to a nullable type.

Unsafe operations

unsafeCast :: String -> Column a -> Column b Source #

Cast a column to any other type. Implements Postgres's :: or CAST( ... AS ... ) operations. This is safe for some conversions, such as uuid to text.

unsafeCoerce :: Column a -> Column b Source #

Deprecated: Will be removed in version 0.6. Use unsafeCoerceColumn instead.

unsafeCoerceColumn :: Column a -> Column b Source #

Treat a Column as though it were of a different type. If such a treatment is not valid then Postgres may fail with an error at SQL run time.

unsafeCompositeField :: Column a -> String -> Column b Source #