Database.Persist.Base

API for database actions. The API deals with fields and entities. In SQL, a field corresponds to a column, and should be a single non-composite value. An entity corresponds to a SQL table, so an entity is a collection of fields.

Documentation

data PersistValue

A raw value which can be stored in any backend and can be marshalled to and from a PersistField.

Constructors

PersistText Text

PersistByteString ByteString

PersistInt64 Int64

PersistDouble Double

PersistBool Bool

PersistDay Day

PersistTimeOfDay TimeOfDay

PersistUTCTime UTCTime

PersistNull

PersistList [PersistValue]

PersistMap [(Text, PersistValue)]

PersistObjectId ByteString

intended especially for MongoDB backend

Instances

Eq PersistValue

Ord PersistValue

Read PersistValue

Show PersistValue

Typeable PersistValue

SinglePiece PersistValue

PersistField PersistValue

data SqlType

A SQL data type. Naming attempts to reflect the underlying Haskell datatypes, eg SqlString instead of SqlVarchar. Different SQL databases may have different translations for these types.

Constructors

SqlString

SqlInt32

SqlInteger

FIXME 8-byte integer; should be renamed SqlInt64

SqlReal

SqlBool

SqlDay

SqlTime

SqlDayTime

SqlBlob

Instances

Eq SqlType

Read SqlType

Show SqlType

Typeable SqlType

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 Int8

PersistField Int16

PersistField Int32

PersistField Int64

PersistField Word8

PersistField Word16

PersistField Word32

PersistField Word64

PersistField String

PersistField Text

PersistField ByteString

PersistField Html

PersistField TimeOfDay

PersistField UTCTime

PersistField Day

PersistField SomePersistField

PersistField PersistValue

PersistField a => PersistField (Maybe a)

PersistField (Key backend entity)

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 EntityField val :: * -> *

Parameters: val and datatype of the field

data Unique val :: ((* -> *) -> * -> *) -> *

Unique keys in existence on this entity.

Methods

persistColumnDef :: EntityField val typ -> ColumnDef

entityDef :: val -> EntityDef

toPersistFields :: val -> [SomePersistField]

fromPersistValues :: [PersistValue] -> Either String val

halfDefined :: val

persistUniqueToFieldNames :: Unique val backend -> [String]

persistUniqueToValues :: Unique val backend -> [PersistValue]

persistUniqueKeys :: val -> [Unique val backend]

class (MonadIO (b m), MonadIO m, Monad (b m), Monad m) => PersistBackend b m where

Methods

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

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

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

Update individual fields on a specific record.

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

Update individual fields on any record matching the given criterion.

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

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

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

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

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

Delete all records matching the given criterion.

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

Get a record by identifier, if available.

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

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

selectEnum :: PersistEntity val => [Filter val] -> [SelectOpt val] -> Enumerator (Key b val, val) (b m) a

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

selectFirst :: PersistEntity val => [Filter val] -> [SelectOpt val] -> b m (Maybe (Key b val, val))

get just the first record for the criterion

selectKeys :: PersistEntity val => [Filter val] -> Enumerator (Key b val) (b m) a

Get the Keys of all records matching the given criterion.

count :: PersistEntity val => [Filter val] -> b m Int

The total number of records fulfilling the given criterion.

Instances

(MonadIO m, MonadBaseControl IO m) => PersistBackend SqlPersist m

data PersistFilter

Constructors

Eq

Ne

Gt

Lt

Ge

Le

In

NotIn

BackendSpecificFilter String

Instances

Read PersistFilter

Show PersistFilter

data PersistUpdate

Constructors

Assign

Add

Subtract

Multiply

Divide

Instances

Bounded PersistUpdate

Enum PersistUpdate

Read PersistUpdate

Show PersistUpdate

data SelectOpt v

Constructors

forall typ . Asc (EntityField v typ)

forall typ . Desc (EntityField v typ)

OffsetBy Int

LimitTo Int

data SomePersistField

Constructors

forall a . PersistField a => SomePersistField a

Instances

PersistField SomePersistField

selectList :: (PersistEntity val, PersistBackend b m) => [Filter val] -> [SelectOpt val] -> b m [(Key b val, val)]

Call select but return the result as a list.

insertBy :: (PersistEntity v, PersistBackend b m) => v -> b m (Either (Key b v, v) (Key b v))

Insert a value, checking for conflicts with any unique constraints. If a duplicate exists in the database, it is returned as Left. Otherwise, the new Key is returned as Right.

getByValue :: (PersistEntity v, PersistBackend b m) => v -> b m (Maybe (Key b v, v))

A modification of getBy, which takes the PersistEntity itself instead of a Unique value. Returns a value matching one of the unique keys. This function makes the most sense on entities with a single Unique constructor.

getJust :: (PersistBackend b m, PersistEntity val, Show (Key b val)) => Key b val -> b m val

Same as get, but for a non-null (not Maybe) foreign key Unsafe unless your database is enforcing that the foreign key is valid

belongsTo :: (PersistBackend b m, PersistEntity ent1, PersistEntity ent2) => (ent1 -> Maybe (Key b ent2)) -> ent1 -> b m (Maybe ent2)

belongsToJust :: (PersistBackend b m, PersistEntity ent1, PersistEntity ent2) => (ent1 -> Key b ent2) -> ent1 -> b m ent2

same as belongsTo, but uses getJust and therefore is similarly unsafe

checkUnique :: (PersistEntity val, PersistBackend b m) => val -> b m Bool

Check whether there are any conflicts for unique keys with this entity and existing entities in the database.

Returns True if the entity would be unique, and could thus safely be inserted; returns False on a conflict.

class PersistEntity a => DeleteCascade a b where

Methods

deleteCascade :: PersistBackend b m => Key b a -> b m ()

deleteCascadeWhere :: (DeleteCascade a b, PersistBackend b m) => [Filter a] -> b m ()

data PersistException

Constructors

PersistError String

Generic Exception

PersistMarshalError String

PersistInvalidField String

PersistForeignConstraintUnmet String

PersistMongoDBError String

PersistMongoDBUnsupported String

Instances

Show PersistException

Typeable PersistException

Exception PersistException

Error PersistException

data Update v

Constructors

forall typ . PersistField typ => Update

Fields

updateField :: EntityField v typ

updateValue :: typ

updateUpdate :: PersistUpdate

updateFieldName :: PersistEntity v => Update v -> String

data Filter v

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.

Constructors

forall typ . PersistField typ => Filter

Fields

filterField :: EntityField v typ

filterValue :: Either typ [typ]

filterFilter :: PersistFilter

FilterAnd [Filter v]

convenient for internal use, not needed for the API

FilterOr [Filter v]

newtype Key backend entity

Constructors

Key

Fields

unKey :: PersistValue

Instances

Eq (Key backend entity)

Ord (Key backend entity)

Read (Key backend entity)

Show (Key backend entity)

SinglePiece (Key SqlPersist entity)

PersistField (Key backend entity)

Definition

data EntityDef

Constructors

EntityDef

Fields

entityName :: String

entityAttribs :: [String]

entityColumns :: [ColumnDef]

entityUniques :: [UniqueDef]

entityDerives :: [String]

Instances

Show EntityDef

type ColumnName = String

type ColumnType = String

data ColumnDef

Constructors

ColumnDef

Fields

columnName :: ColumnName

columnType :: ColumnType

columnAttribs :: [String]

Instances

Show ColumnDef

data UniqueDef

Constructors

UniqueDef

Fields

uniqueName :: String

uniqueColumns :: [ColumnName]

Instances

Show UniqueDef

fst3 :: forall t t1 t2. (t, t1, t2) -> t

snd3 :: forall t t1 t2. (t, t1, t2) -> t1

third3 :: forall t t1 t2. (t, t1, t2) -> t2

limitOffsetOrder :: PersistEntity val => [SelectOpt val] -> (Int, Int, [SelectOpt val])

Config

class PersistConfig c where

Represents a value containing all the configuration options for a specific backend. This abstraction makes it easier to write code that can easily swap backends.

Associated Types

type PersistConfigBackend c :: (* -> *) -> * -> *

type PersistConfigPool c

Methods

loadConfig :: TextObject -> Either String c

withPool :: (Applicative m, MonadBaseControl IO m, MonadIO m) => c -> (PersistConfigPool c -> m a) -> m a

I really don't want Applicative here, but it's necessary for Mongo.

runPool :: (MonadBaseControl IO m, MonadIO m) => c -> PersistConfigBackend c m a -> PersistConfigPool c -> m a