| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Database.Beam.Backend.Types
Contents
- class BeamBackend be where
- type BackendFromField be :: * -> Constraint
- newtype Auto x = Auto {}
- data FromBackendRowF be f where
- ParseOneField :: BackendFromField be a => (a -> f) -> FromBackendRowF be f
- PeekField :: BackendFromField be a => (Maybe a -> f) -> FromBackendRowF be f
- CheckNextNNull :: Int -> (Bool -> f) -> FromBackendRowF be f
- type FromBackendRowM be = F (FromBackendRowF be)
- parseOneField :: BackendFromField be a => FromBackendRowM be a
- peekField :: BackendFromField be a => FromBackendRowM be (Maybe a)
- checkNextNNull :: Int -> FromBackendRowM be Bool
- class BeamBackend be => FromBackendRow be a where
- data Exposed x
- data Nullable (c :: * -> *) x
Documentation
class BeamBackend be Source #
Class for all beam backends
Associated Types
type BackendFromField be :: * -> Constraint Source #
Requirements to marshal a certain type from a database of a particular backend
Instances
Newtype wrapper for types that may be given default values by the database. Essentially, a wrapper around 'Maybe x'.
When a value of type 'Auto x' is written to a database (via INSERT or
UPDATE, for example), backends will translate a Nothing value into an
expression that will evaluate to whatever default value the database would
choose. This is useful to insert rows with columns that are
auto-incrementable or have a DEFAULT value.
When read from the database, the wrapped value will always be a Just
value. This isn't currently enforced at the type-level, but may be in
future versions of beam.
Instances
| (BeamBackend be, FromBackendRow be (Maybe x)) => FromBackendRow be (Auto x) Source # | |
| HasSqlValueSyntax Value (Maybe x) => HasSqlValueSyntax Value (Auto x) Source # | |
| Eq x => Eq (Auto x) Source # | |
| Ord x => Ord (Auto x) Source # | |
| Read x => Read (Auto x) Source # | |
| Show x => Show (Auto x) Source # | |
| Generic (Auto x) Source # | |
| Monoid x => Monoid (Auto x) Source # | |
| ToJSON a => ToJSON (Auto a) Source # | |
| FromJSON a => FromJSON (Auto a) Source # | |
| type Rep (Auto x) Source # | |
data FromBackendRowF be f where Source #
Constructors
| ParseOneField :: BackendFromField be a => (a -> f) -> FromBackendRowF be f | |
| PeekField :: BackendFromField be a => (Maybe a -> f) -> FromBackendRowF be f | |
| CheckNextNNull :: Int -> (Bool -> f) -> FromBackendRowF be f |
Instances
| Functor (FromBackendRowF be) Source # | |
type FromBackendRowM be = F (FromBackendRowF be) Source #
parseOneField :: BackendFromField be a => FromBackendRowM be a Source #
peekField :: BackendFromField be a => FromBackendRowM be (Maybe a) Source #
checkNextNNull :: Int -> FromBackendRowM be Bool Source #
class BeamBackend be => FromBackendRow be a where Source #
Methods
fromBackendRow :: FromBackendRowM be a Source #
fromBackendRow :: BackendFromField be a => FromBackendRowM be a Source #
Instances
newtype mainly used to inspect tho tag structure of a particular
Beamable. Prevents overlapping instances in some case. Usually not used
in end-user code.
Instances
| FieldsFulfillConstraintNullable c t => GFieldsFulfillConstraint c (K1 * R (t (Nullable Exposed))) (K1 * R (t (Nullable Identity))) (K1 * R (t (Nullable (WithConstraint c)))) Source # | |
| FieldsFulfillConstraint c t => GFieldsFulfillConstraint c (K1 * R (t Exposed)) (K1 * R (t Identity)) (K1 * R (t (WithConstraint c))) Source # | |
| c x => GFieldsFulfillConstraint c (K1 * R (Exposed x)) (K1 * R x) (K1 * R (WithConstraint c x)) Source # | |
data Nullable (c :: * -> *) x Source #
Support for NULLable Foreign Key references.
data MyTable f = MyTable
{ nullableRef :: PrimaryKey AnotherTable (Nullable f)
, ... }
deriving (Generic, Typeable)See Columnar for more information.
Instances