Moduleopaleye-0.10.8.0Haskell2010

Opaleye.Column

Deprecated. Use Opaleye.Field instead. Will be removed in version 0.11.

Functions for working directly with Columns.

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

1 type
8 values

Packageopaleye-0.10.8.0
Exports10
LanguageHaskell2010
LicenceBSD-3-Clause
SourceColumn.hs

Column

1 declaration

familytype family Column a where

Do not use. Use Field instead. Will be removed in a later version.

Equations

Column (Nullable a) = FieldNullable a
Column a = Field a

Working with `NULL`

3 declarations

datadata Nullable a

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

valuenull :: Column (Nullable a)

A NULL of any type

valueisNull :: Column (Nullable a) -> Column PGBool

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

Unsafe operations

3 declarations

valueunsafeCast :: String -> Field_ n a -> Field_ n b

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.

valueunsafeCoerceColumn :: Field_ n a -> Field_ n' b

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.

valueunsafeCompositeField :: Field_ n a -> String -> Field_ n' b

Entire module

3 declarations

valueisNull :: Column (Nullable a) -> Column PGBool

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

valuejoinNullable :: Column (Nullable (Nullable a)) -> Column (Nullable a)

valuenull :: Column (Nullable a)

A NULL of any type

Column

Equations

Working with NULL

Unsafe operations

Entire module

Working with `NULL`