Database.Persist

Documentation

class PersistField a where

A value which can be marshalled to and from a PersistValue.

Methods

toPersistValue :: a -> PersistValue

fromPersistValue :: PersistValue -> Either String a

sqlType :: a -> SqlType

isNullable :: a -> Bool

Instances

PersistField Bool

PersistField Double

PersistField Int

PersistField Int64

PersistField String

PersistField ByteString

PersistField Text

PersistField TimeOfDay

PersistField UTCTime

PersistField Day

PersistField SomePersistField

PersistField a => PersistField (Maybe a)

PersistField (Html ())

class PersistEntity val where

A single database entity. For example, if writing a blog application, a blog entry would be an entry, containing fields such as title and content.

Associated Types

data Key val

The unique identifier associated with this entity. In general, backends also define a type synonym for this, such that "type MyEntityId = Key MyEntity".

data Update val

Fields which can be updated using the update and updateWhere functions.

data Filter val

Filters which are available for select, updateWhere and deleteWhere. Each filter constructor specifies the field being filtered on, the type of comparison applied (equals, not equals, etc) and the argument for the comparison.

data Order val

How you can sort the results of a select.

data Unique val

Unique keys in existence on this entity.

Methods

entityDef :: val -> EntityDef

toPersistFields :: val -> [SomePersistField]

fromPersistValues :: [PersistValue] -> Either String val

halfDefined :: val

toPersistKey :: Int64 -> Key val

fromPersistKey :: Key val -> Int64

showPersistKey :: Key val -> String

persistFilterToFieldName :: Filter val -> String

persistFilterToFilter :: Filter val -> PersistFilter

persistFilterIsNull :: Filter val -> Bool

persistFilterToValue :: Filter val -> PersistValue

persistOrderToFieldName :: Order val -> String

persistOrderToOrder :: Order val -> PersistOrder

persistUpdateToFieldName :: Update val -> String

persistUpdateToValue :: Update val -> PersistValue

persistUniqueToFieldNames :: Unique val -> [String]

persistUniqueToValues :: Unique val -> [PersistValue]

class PersistBackend m where

Methods

initialize :: PersistEntity val => val -> m ()

Prepare database for this entity, if necessary. In SQL, this creates values and indices if they don't exist. The first argument is not used, so you can used undefined.

insert :: PersistEntity val => val -> m (Key val)

Create a new record in the database, returning the newly created identifier.

replace :: PersistEntity val => Key val -> val -> m ()

Replace the record in the database with the given key. Result is undefined if such a record does not exist.

update :: PersistEntity val => Key val -> [Update val] -> m ()

Update individual fields on a specific record.

updateWhere :: PersistEntity val => [Filter val] -> [Update val] -> m ()

Update individual fields on any record matching the given criterion.

delete :: PersistEntity val => Key val -> m ()

Delete a specific record by identifier. Does nothing if record does not exist.

deleteBy :: PersistEntity val => Unique val -> m ()

Delete a specific record by unique key. Does nothing if no record matches.

deleteWhere :: PersistEntity val => [Filter val] -> m ()

Delete all records matching the given criterion.

get :: PersistEntity val => Key val -> m (Maybe val)

Get a record by identifier, if available.

getBy :: PersistEntity val => Unique val -> m (Maybe (Key val, val))

Get a record by unique key, if available. Returns also the identifier.

select :: PersistEntity val => [Filter val] -> [Order val] -> m [(Key val, val)]

Get all records matching the given criterion in the specified order. Returns also the identifiers.

mkPersist :: [EntityDef] -> Q [Dec]

Create data types and appropriate PersistEntity instances for the given EntityDefs. Works well with the persist quasi-quoter.

persist :: QuasiQuoter

Converts a quasi-quoted syntax into a list of entity definitions, to be used as input to the template haskell generation code (mkPersist).