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module Database.Persist.Sql.Types
( module Database.Persist.Sql.Types
, SqlBackend, SqlReadBackend (..), SqlWriteBackend (..)
, Statement (..), LogFunc, InsertSqlResult (..)
, readToUnknown, readToWrite, writeToUnknown
, SqlBackendCanRead, SqlBackendCanWrite, SqlReadT, SqlWriteT, IsSqlBackend
, OverflowNatural(..)
, ConnectionPoolConfig(..)
) where
import Control.Exception (Exception(..))
import Control.Monad.Logger (NoLoggingT)
import Control.Monad.Trans.Reader (ReaderT(..))
import Control.Monad.Trans.Resource (ResourceT)
import Data.Pool (Pool)
import Data.Text (Text)
import Data.Time (NominalDiffTime)
import Database.Persist.Sql.Types.Internal
import Database.Persist.Types
data Column = Column
{ cName :: !FieldNameDB
, cNull :: !Bool
, cSqlType :: !SqlType
, cDefault :: !(Maybe Text)
, cGenerated :: !(Maybe Text)
, cDefaultConstraintName :: !(Maybe ConstraintNameDB)
, cMaxLen :: !(Maybe Integer)
, cReference :: !(Maybe ColumnReference)
}
deriving (Eq, Ord, Show)
-- | This value specifies how a field references another table.
--
-- @since 2.11.0.0
data ColumnReference = ColumnReference
{ crTableName :: !EntityNameDB
-- ^ The table name that the
--
-- @since 2.11.0.0
, crConstraintName :: !ConstraintNameDB
-- ^ The name of the foreign key constraint.
--
-- @since 2.11.0.0
, crFieldCascade :: !FieldCascade
-- ^ Whether or not updates/deletions to the referenced table cascade
-- to this table.
--
-- @since 2.11.0.0
}
deriving (Eq, Ord, Show)
data PersistentSqlException = StatementAlreadyFinalized Text
| Couldn'tGetSQLConnection
deriving Show
instance Exception PersistentSqlException
type SqlPersistT = ReaderT SqlBackend
type SqlPersistM = SqlPersistT (NoLoggingT (ResourceT IO))
type ConnectionPool = Pool SqlBackend
-- | Values to configure a pool of database connections. See "Data.Pool" for details.
--
-- @since 2.11.0.0
data ConnectionPoolConfig = ConnectionPoolConfig
{ connectionPoolConfigStripes :: Int -- ^ How many stripes to divide the pool into. See "Data.Pool" for details. Default: 1.
, connectionPoolConfigIdleTimeout :: NominalDiffTime -- ^ How long connections can remain idle before being disposed of, in seconds. Default: 600
, connectionPoolConfigSize :: Int -- ^ How many connections should be held in the connection pool. Default: 10
}
deriving (Show)
-- TODO: Bad defaults for SQLite maybe?
-- | Initializes a ConnectionPoolConfig with default values. See the documentation of 'ConnectionPoolConfig' for each field's default value.
--
-- @since 2.11.0.0
defaultConnectionPoolConfig :: ConnectionPoolConfig
defaultConnectionPoolConfig = ConnectionPoolConfig 1 600 10
-- $rawSql
--
-- Although it covers most of the useful cases, @persistent@'s
-- API may not be enough for some of your tasks. May be you need
-- some complex @JOIN@ query, or a database-specific command
-- needs to be issued.
--
-- To issue raw SQL queries, use 'rawSql'. It does all the hard work of
-- automatically parsing the rows of the result. It may return:
--
-- * An 'Entity', that which 'selectList' returns.
-- All of your entity's fields are
-- automatically parsed.
--
-- * A @'Single' a@, which is a single, raw column of type @a@.
-- You may use a Haskell type (such as in your entity
-- definitions), for example @Single Text@ or @Single Int@,
-- or you may get the raw column value with @Single
-- 'PersistValue'@.
--
-- * A tuple combining any of these (including other tuples).
-- Using tuples allows you to return many entities in one
-- query.
--
-- The only difference between issuing SQL queries with 'rawSql'
-- and using other means is that we have an /entity selection/
-- /placeholder/, the double question mark @??@. It /must/ be
-- used whenever you want to @SELECT@ an 'Entity' from your
-- query. Here's a sample SQL query @sampleStmt@ that may be
-- issued:
--
-- @
-- SELECT ??, ??
-- FROM \"Person\", \"Likes\", \"Object\"
-- WHERE \"Person\".id = \"Likes\".\"personId\"
-- AND \"Object\".id = \"Likes\".\"objectId\"
-- AND \"Person\".name LIKE ?
-- @
--
-- To use that query, you could say
--
-- @
-- do results <- 'rawSql' sampleStmt [\"%Luke%\"]
-- forM_ results $
-- \\( Entity personKey person
-- , Entity objectKey object
-- ) -> do ...
-- @
--
-- Note that 'rawSql' knows how to replace the double question
-- marks @??@ because of the type of the @results@.
-- | A single column (see 'rawSql'). Any 'PersistField' may be
-- used here, including 'PersistValue' (which does not do any
-- processing).
newtype Single a = Single {unSingle :: a}
deriving (Eq, Ord, Show, Read)
|
