Database.Persist.Base
Description
This defines the API for performing database actions. There are two levels to this API: dealing with fields, and dealing with entities. In SQL, a field corresponds to a column, and should be a single, non-composite value. An entity corresponds to a SQL table. In other words: An entity is a collection of fields.
- data PersistValue
- data SqlType
- = SqlString
- | SqlInteger
- | SqlReal
- | SqlBool
- | SqlDay
- | SqlTime
- | SqlDayTime
- | SqlBlob
- class PersistField a where
- toPersistValue :: a -> PersistValue
- fromPersistValue :: PersistValue -> Either String a
- sqlType :: a -> SqlType
- isNullable :: a -> Bool
- class PersistEntity val where
- data Key val
- data Update val
- data Filter val
- data Order val
- data Unique val
- 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]
- data EntityDef = EntityDef {
- entityName :: String
- entityAttribs :: [String]
- entityColumns :: [(String, String, [String])]
- entityUniques :: [(String, [String])]
- entityDerives :: [String]
- class PersistBackend m where
- initialize :: PersistEntity val => val -> m ()
- insert :: PersistEntity val => val -> m (Key val)
- replace :: PersistEntity val => Key val -> val -> m ()
- update :: PersistEntity val => Key val -> [Update val] -> m ()
- updateWhere :: PersistEntity val => [Filter val] -> [Update val] -> m ()
- delete :: PersistEntity val => Key val -> m ()
- deleteBy :: PersistEntity val => Unique val -> m ()
- deleteWhere :: PersistEntity val => [Filter val] -> m ()
- get :: PersistEntity val => Key val -> m (Maybe val)
- getBy :: PersistEntity val => Unique val -> m (Maybe (Key val, val))
- select :: PersistEntity val => [Filter val] -> [Order val] -> m [(Key val, val)]
- data PersistFilter
- data PersistOrder
- data SomePersistField = forall a . PersistField a => SomePersistField a
Documentation
data PersistValue Source
A raw value which can be stored in any backend and can be marshalled to
and from a PersistField.
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 | |
| SqlInteger | |
| SqlReal | |
| SqlBool | |
| SqlDay | |
| SqlTime | |
| SqlDayTime | |
| SqlBlob |
class PersistField a whereSource
A value which can be marshalled to and from a PersistValue.
Methods
toPersistValue :: a -> PersistValueSource
fromPersistValue :: PersistValue -> Either String aSource
isNullable :: a -> BoolSource
class PersistEntity val whereSource
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
The unique identifier associated with this entity. In general, backends also define a type synonym for this, such that "type MyEntityId = Key MyEntity".
Fields which can be updated using the update and updateWhere
functions.
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.
How you can sort the results of a select.
Unique keys in existence on this entity.
Methods
entityDef :: val -> EntityDefSource
toPersistFields :: val -> [SomePersistField]Source
fromPersistValues :: [PersistValue] -> Either String valSource
halfDefined :: valSource
toPersistKey :: Int64 -> Key valSource
fromPersistKey :: Key val -> Int64Source
showPersistKey :: Key val -> StringSource
persistFilterToFieldName :: Filter val -> StringSource
persistFilterToFilter :: Filter val -> PersistFilterSource
persistFilterIsNull :: Filter val -> BoolSource
persistFilterToValue :: Filter val -> PersistValueSource
persistOrderToFieldName :: Order val -> StringSource
persistOrderToOrder :: Order val -> PersistOrderSource
persistUpdateToFieldName :: Update val -> StringSource
persistUpdateToValue :: Update val -> PersistValueSource
persistUniqueToFieldNames :: Unique val -> [String]Source
persistUniqueToValues :: Unique val -> [PersistValue]Source
Constructors
| EntityDef | |
Fields
| |
class PersistBackend m whereSource
Methods
initialize :: PersistEntity val => val -> m ()Source
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)Source
Create a new record in the database, returning the newly created identifier.
replace :: PersistEntity val => Key val -> val -> m ()Source
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 ()Source
Update individual fields on a specific record.
updateWhere :: PersistEntity val => [Filter val] -> [Update val] -> m ()Source
Update individual fields on any record matching the given criterion.
delete :: PersistEntity val => Key val -> m ()Source
Delete a specific record by identifier. Does nothing if record does not exist.
deleteBy :: PersistEntity val => Unique val -> m ()Source
Delete a specific record by unique key. Does nothing if no record matches.
deleteWhere :: PersistEntity val => [Filter val] -> m ()Source
Delete all records matching the given criterion.
get :: PersistEntity val => Key val -> m (Maybe val)Source
Get a record by identifier, if available.
getBy :: PersistEntity val => Unique val -> m (Maybe (Key val, val))Source
Get a record by unique key, if available. Returns also the identifier.
select :: PersistEntity val => [Filter val] -> [Order val] -> m [(Key val, val)]Source
Get all records matching the given criterion in the specified order. Returns also the identifiers.
data PersistFilter Source
Instances
data PersistOrder Source
Instances