Moduleselda-0.5.2.1Haskell2010

Database.Selda.Backend.Internal

Internal backend API. Using anything exported from this module may or may not invalidate any safety guarantees made by Selda; use at your own peril.

18 types
2 classes
14 values

Packageselda-0.5.2.1
Exports34
LanguageHaskell2010
LicenceMIT
SourceInternal.hs

newtypenewtype StmtID

A prepared statement identifier. Guaranteed to be unique per application.

Constructors

StmtID Int

Instances3Eq, Ord, Show

Eq StmtIDDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal
Ord StmtIDDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal
Show StmtIDDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal

datadata BackendID

Uniquely identifies some particular backend.

When publishing a new backend, consider submitting a pull request with a constructor for your backend instead of using the Other constructor.

Constructors

SQLite
PostgreSQL
Other Text

Instances3Eq, Ord, Show

Eq BackendIDDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal
Ord BackendIDDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal
Show BackendIDDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal

typetype QueryRunner a = Text -> [Param] -> IO a

A function which executes a query and gives back a list of extensible tuples; one tuple per result row, and one tuple element per column.

datadata SeldaBackend b

A collection of functions making up a Selda backend.

Constructors

SeldaBackend
- runStmt :: Text -> [Param] -> IO (Int, [[SqlValue]])
  Execute an SQL statement.
- runStmtWithPK :: Text -> [Param] -> IO Int64
  Execute an SQL statement and return the last inserted primary key, where the primary key is auto-incrementing. Backends must take special care to make this thread-safe.
- prepareStmt :: StmtID -> [SqlTypeRep] -> Text -> IO Dynamic
  Prepare a statement using the given statement identifier.
- runPrepared :: Dynamic -> [Param] -> IO (Int, [[SqlValue]])
  Execute a prepared statement.
- getTableInfo :: TableName -> IO TableInfo
  Get a list of all columns in the given table, with the type and any modifiers for each column. Return an empty list if the given table does not exist.
- ppConfig :: PPConfig
  SQL pretty-printer configuration.
- closeConnection :: SeldaConnection b -> IO ()
  Close the currently open connection.
- backendId :: BackendID
  Unique identifier for this backend.
- disableForeignKeys :: Bool -> IO ()
  Turn on or off foreign key checking, and initiate/commit a transaction.
  When implementing this function, it is safe to assume that disableForeignKeys True will always be called exactly once before each disableForeignKeys False.

datadata SeldaConnection b

Constructors

SeldaConnection
- connBackend :: !SeldaBackend b
  The backend used by the current connection.
- connDbId :: Text
  A string uniquely identifying the database used by this connection. This could be, for instance, a PostgreSQL connection string or the absolute path to an SQLite file.
- connStmts :: !IORef (IntMap SeldaStmt)
  All statements prepared for this connection.
- connClosed :: !IORef Bool
  Is the connection closed?
- connLock :: !MVar ()
  Lock to prevent this connection from being used concurrently by multiple invocations of runSeldaT.

datadata SeldaStmt

A prepared statement.

Constructors

SeldaStmt
- stmtHandle :: !Dynamic
  Backend-specific handle to the prepared statement.
- stmtText :: !Text
  The SQL code for the statement.
- stmtParams :: ![Either Int Param]
  All parameters to be passed to the prepared statement. Parameters that are unique to each invocation are specified as indices starting at 0. Backends implementing runPrepared should probably ignore this field.

classclass MonadIO m => MonadSelda (m :: Type -> Type) where

Some monad with Selda SQL capabilitites.

Associated types

type family Backend (m :: Type -> Type)
Type of database backend used by m.

Methods

withConnection :: (SeldaConnection (Backend m) -> m a) -> m a
Pass a Selda connection to the given computation and execute it. After the computation finishes, withConnection is free to do anything it likes to the connection, including closing it or giving it to another Selda computation. Thus, the computation must take care never to return or otherwise access the connection after returning.
transact :: m a -> m a
Perform the given computation as a transaction. Implementations must ensure that subsequent calls to withConnection within the same transaction always passes the same connection to its argument.

Instances1MonadSelda

(MonadIO m, MonadMask m) => MonadSelda (SeldaT b m)Defined in selda-0.5.2.1 · Database.Selda.Backend.Internal

newtypenewtype SeldaT b (m :: Type -> Type) a

Monad transformer adding Selda SQL capabilities.

Constructors

S
- unS :: ReaderT (SeldaConnection b) m a

Instances11MonadTrans, Monad, Functor, MonadFail, Applicative, MonadIO, …

MonadTrans (SeldaT b)Defined in selda-0.5.2.1 · Database.Selda.Backend.Internal
Monad m => Monad (SeldaT b m)Defined in selda-0.5.2.1 · Database.Selda.Backend.Internal
Functor m => Functor (SeldaT b m)Defined in selda-0.5.2.1 · Database.Selda.Backend.Internal
MonadFail m => MonadFail (SeldaT b m)Defined in selda-0.5.2.1 · Database.Selda.Backend.Internal
Applicative m => Applicative (SeldaT b m)Defined in selda-0.5.2.1 · Database.Selda.Backend.Internal
MonadIO m => MonadIO (SeldaT b m)Defined in selda-0.5.2.1 · Database.Selda.Backend.Internal
MonadCatch m => MonadCatch (SeldaT b m)Defined in selda-0.5.2.1 · Database.Selda.Backend.Internal
MonadMask m => MonadMask (SeldaT b m)Defined in selda-0.5.2.1 · Database.Selda.Backend.Internal
MonadThrow m => MonadThrow (SeldaT b m)Defined in selda-0.5.2.1 · Database.Selda.Backend.Internal
(MonadIO m, MonadMask m) => MonadSelda (SeldaT b m)Defined in selda-0.5.2.1 · Database.Selda.Backend.Internal
type Backend (SeldaT b m) = bDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal

typetype SeldaM b = SeldaT b IO

The simplest form of Selda computation; SeldaT specialized to IO.

datadata SeldaError

Thrown by any function in SeldaT if an error occurs.

Constructors

DbError String
Unable to open or connect to database.
SqlError String
An error occurred while executing query.
UnsafeError String
An error occurred due to improper use of an unsafe function.

Instances3Eq, Show, Exception

Eq SeldaErrorDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal
Show SeldaErrorDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal
Exception SeldaErrorDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal

datadata Param where

A parameter to a prepared SQL statement.

Constructors

Param :: !Lit a -> Param

Instances3Eq, Ord, Show

Eq ParamDefined in selda-0.5.2.1 · Database.Selda.SQL
Ord ParamDefined in selda-0.5.2.1 · Database.Selda.SQL
Show ParamDefined in selda-0.5.2.1 · Database.Selda.SQL

datadata Lit a where

An SQL literal.

Constructors

LText :: !Text -> Lit Text
LInt32 :: !Int32 -> Lit Int32
LInt64 :: !Int64 -> Lit Int64
LDouble :: !Double -> Lit Double
LBool :: !Bool -> Lit Bool
LDateTime :: !UTCTime -> Lit UTCTime
LDate :: !Day -> Lit Day
LTime :: !TimeOfDay -> Lit TimeOfDay
LJust :: SqlType a1 => !Lit a1 -> Lit (Maybe a1)
LBlob :: !ByteString -> Lit ByteString
LNull :: SqlType a1 => Lit (Maybe a1)
LCustom :: SqlTypeRep -> Lit a1 -> Lit a
LUUID :: !UUID -> Lit UUID

Instances3Eq, Ord, Show

Eq (Lit a)Defined in selda-0.5.2.1 · Database.Selda.SqlType
Ord (Lit a)Defined in selda-0.5.2.1 · Database.Selda.SqlType
Show (Lit a)Defined in selda-0.5.2.1 · Database.Selda.SqlType

datadata ColAttr

Column attributes such as nullability, auto increment, etc. When adding elements, make sure that they are added in the order required by SQL syntax, as this list is only sorted before being pretty-printed.

Constructors

Primary
AutoPrimary AutoIncType
Required
Optional
Unique
Indexed (Maybe IndexMethod)

Instances3Eq, Ord, Show

Eq ColAttrDefined in selda-0.5.2.1 · Database.Selda.Table.Type
Ord ColAttrDefined in selda-0.5.2.1 · Database.Selda.Table.Type
Show ColAttrDefined in selda-0.5.2.1 · Database.Selda.Table.Type

datadata AutoIncType

Strongly or weakly auto-incrementing primary key?

Weak Strong

Instances3Eq, Ord, Show

Eq AutoIncTypeDefined in selda-0.5.2.1 · Database.Selda.Table.Type
Ord AutoIncTypeDefined in selda-0.5.2.1 · Database.Selda.Table.Type
Show AutoIncTypeDefined in selda-0.5.2.1 · Database.Selda.Table.Type

classclass Typeable a => SqlType a where

Any datatype representable in (Selda's subset of) SQL.

Methods

mkLit :: a -> Lit a
Create a literal of this type.
sqlType :: Proxy a -> SqlTypeRep
The SQL representation for this type.
fromSql :: SqlValue -> a
Convert an SqlValue into this type.
defaultValue :: Lit a
Default value when using def at this type.

Instances19SqlType, …

SqlType ByteStringDefined in selda-0.5.2.1 · Database.Selda.SqlType
SqlType ByteStringDefined in selda-0.5.2.1 · Database.Selda.SqlType
SqlType Int32Defined in selda-0.5.2.1 · Database.Selda.SqlType
SqlType Int64Defined in selda-0.5.2.1 · Database.Selda.SqlType
SqlType BoolDefined in selda-0.5.2.1 · Database.Selda.SqlType
SqlType DoubleDefined in selda-0.5.2.1 · Database.Selda.SqlType
SqlType IntDefined in selda-0.5.2.1 · Database.Selda.SqlType
SqlType OrderingDefined in selda-0.5.2.1 · Database.Selda.SqlType
SqlType RowIDDefined in selda-0.5.2.1 · Database.Selda.SqlType
SqlType TextDefined in selda-0.5.2.1 · Database.Selda.SqlType
SqlType TextDefined in selda-0.5.2.1 · Database.Selda.SqlType
SqlType DayDefined in selda-0.5.2.1 · Database.Selda.SqlType
SqlType UTCTimeDefined in selda-0.5.2.1 · Database.Selda.SqlType
SqlType TimeOfDayDefined in selda-0.5.2.1 · Database.Selda.SqlType
SqlType UUIDDefined in selda-0.5.2.1 · Database.Selda.SqlType
defaultValue for UUIDs is the all-zero RFC4122 nil UUID.
Typeable a => SqlType (ID a)Defined in selda-0.5.2.1 · Database.Selda.SqlType
Typeable a => SqlType (UUID' a)Defined in selda-0.5.2.1 · Database.Selda.SqlType
defaultValue for UUIDs is the all-zero RFC4122 nil UUID.
SqlType a => SqlType (Maybe a)Defined in selda-0.5.2.1 · Database.Selda.SqlType
(TypeError ((('Text "'Only " ':<>: 'ShowType a) ':<>: 'Text "' is not a proper SQL type.") ':$$: 'Text "Use 'the' to access the value of the column."), Typeable a) => SqlType (Only a)Defined in selda-0.5.2.1 · Database.Selda

datadata SqlValue where

Some value that is representable in SQL.

Constructors

Instances1Show

Show SqlValueDefined in selda-0.5.2.1 · Database.Selda.SqlType

datadata SqlTypeRep

Representation of an SQL type.

TText TRowID TInt64 TInt32 TFloat TBool TDateTime TDate TTime TBlob TUUID TJSON

Instances3Eq, Ord, Show

Eq SqlTypeRepDefined in selda-0.5.2.1 · Database.Selda.SqlType
Ord SqlTypeRepDefined in selda-0.5.2.1 · Database.Selda.SqlType
Show SqlTypeRepDefined in selda-0.5.2.1 · Database.Selda.SqlType

datadata PPConfig

Backend-specific configuration for the SQL pretty-printer.

Constructors

PPConfig
- ppType :: SqlTypeRep -> Text
  The SQL type name of the given type.
  This function should be used everywhere a type is needed to be printed but in primary keys position. This is due to the fact that some backends might have a special representation of primary keys (using sequences are such). If you have such a need, please use the ppTypePK record instead.
- ppTypeHook :: SqlTypeRep -> [ColAttr] -> (SqlTypeRep -> Text) -> Text
  Hook that allows you to modify ppType output.
- ppTypePK :: SqlTypeRep -> Text
  The SQL type name of the given type for primary keys uses.
- ppPlaceholder :: Int -> Text
  Parameter placeholder for the nth parameter.
- ppColAttrs :: [ColAttr] -> Text
  List of column attributes.
- ppColAttrsHook :: SqlTypeRep -> [ColAttr] -> ([ColAttr] -> Text) -> Text
  Hook that allows you to modify ppColAttrs output.
- ppAutoIncInsert :: Text
  The value used for the next value for an auto-incrementing column. For instance, DEFAULT for PostgreSQL, and NULL for SQLite.
- ppMaxInsertParams :: Maybe Int
  Insert queries may have at most this many parameters; if an insertion has more parameters than this, it will be chunked.
  Note that only insertions of multiple rows are chunked. If your table has more than this many columns, you should really rethink your database design.
- ppIndexMethodHook :: IndexMethod -> Text
  CREATE INDEX suffix to indicate that the index should use the given index method.

valuedefPPConfig :: PPConfig

Default settings for pretty-printing. Geared towards SQLite.

The default definition of ppTypePK is 'defType, so that you don’t have to do anything special if you don’t use special types for primary keys.

datadata TableInfo

Comprehensive information about a table.

Constructors

TableInfo
- tableInfoName :: TableName
  Name of the table.
- tableColumnInfos :: [ColumnInfo]
  Ordered information about each table column.
- tableUniqueGroups :: [[ColName]]
  Unordered list of all (non-PK) uniqueness constraints on this table.
- tablePrimaryKey :: [ColName]
  Unordered list of all primary key constraints on this table.

Instances2Eq, Show

Eq TableInfoDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal
Show TableInfoDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal

datadata ColumnInfo

Comprehensive information about a column.

Constructors

ColumnInfo
- colName :: ColName
  Name of the column.
- colType :: Either Text SqlTypeRep
  Selda type of the column, or the type name given by the database if Selda couldn't make sense of the type.
- colIsAutoPrimary :: Bool
  Is the given column auto-incrementing?
- colIsNullable :: Bool
  Can the column be NULL?
- colHasIndex :: Bool
  Is the column explicitly indexed (i.e. using indexed)?
- colFKs :: [(TableName, ColName)]
  Any foreign key (table, column) pairs referenced by this column.

Instances2Eq, Show

Eq ColumnInfoDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal
Show ColumnInfoDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal

valuetableInfo :: Table a -> TableInfo

Get the column information for each column in the given table.

valuefromColInfo :: ColInfo -> ColumnInfo

Convert a ColInfo into a ColumnInfo.

valueisAutoPrimary :: ColAttr -> Bool

valueisPrimary :: ColAttr -> Bool

valueisUnique :: ColAttr -> Bool

valuesqlDateTimeFormat :: String

Format string used to represent date and time when representing timestamps as text. If at all possible, use SqlUTCTime instead.

valuesqlDateFormat :: String

Format string used to represent date when representing dates as text. If at all possible, use SqlDate instead.

valuesqlTimeFormat :: String

Format string used to represent time of day when representing time as text. If at all possible, use SqlTime instead.

valuefreshStmtId :: MonadIO m => m StmtID

Generate a fresh statement identifier, guaranteed to be unique per process.

valuenewConnection

:: MonadIO m
=> SeldaBackend b
-> Text
-> m (SeldaConnection b)

Create a new Selda connection for the given backend and database identifier string.

valueallStmts :: SeldaConnection b -> IO [(StmtID, Dynamic)]

Get all statements and their corresponding identifiers for the current connection.

valuerunSeldaT

:: (MonadIO m, MonadMask m)
=> SeldaT b m a
-> SeldaConnection b
-> m a

Run a Selda transformer. Backends should use this to implement their withX functions.

valuewithBackend :: MonadSelda m => (SeldaBackend (Backend m) -> m a) -> m a

Get the backend in use by the computation.