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{-# LANGUAGE RankNTypes #-}
module Database.Persist.SqlBackend.Internal.MkSqlBackend where
import Control.Monad.Logger (Loc, LogLevel, LogSource, LogStr)
import Data.Text (Text)
import Database.Persist.Names
import Database.Persist.SqlBackend.Internal.InsertSqlResult
import Database.Persist.SqlBackend.Internal.IsolationLevel
import Database.Persist.SqlBackend.Internal.Statement
import Database.Persist.Types.Base
import Data.Map (Map)
import Data.IORef (IORef)
-- | This type shares many of the same field names as the 'SqlBackend' type.
-- It's useful for library authors to use this when migrating from using the
-- 'SqlBackend' constructor directly to the 'mkSqlBackend' function.
--
-- This type will only contain required fields for constructing a 'SqlBackend'.
-- For fields that aren't present on this record, you'll want to use the various
-- @set@ functions or
--
-- @since 2.13.0.0
data MkSqlBackendArgs = MkSqlBackendArgs
{ connPrepare :: Text -> IO Statement
-- ^ This function should prepare a 'Statement' in the target database,
-- which should allow for efficient query reuse.
, connInsertSql :: EntityDef -> [PersistValue] -> InsertSqlResult
-- ^ This function generates the SQL and values necessary for
-- performing an insert against the database.
, connStmtMap :: IORef (Map Text Statement)
-- ^ A reference to the cache of statements. 'Statement's are keyed by
-- the 'Text' queries that generated them.
, connClose :: IO ()
-- ^ Close the underlying connection.
, connMigrateSql
:: [EntityDef]
-> (Text -> IO Statement)
-> EntityDef
-> IO (Either [Text] [(Bool, Text)])
-- ^ This function returns the migrations required to include the
-- 'EntityDef' parameter in the @['EntityDef']@ database. This might
-- include creating a new table if the entity is not present, or
-- altering an existing table if it is.
, connBegin :: (Text -> IO Statement) -> Maybe IsolationLevel -> IO ()
-- ^ A function to begin a transaction for the underlying database.
, connCommit :: (Text -> IO Statement) -> IO ()
-- ^ A function to commit a transaction to the underlying database.
, connRollback :: (Text -> IO Statement) -> IO ()
-- ^ A function to roll back a transaction on the underlying database.
, connEscapeFieldName :: FieldNameDB -> Text
-- ^ A function to extract and escape the name of the column corresponding
-- to the provided field.
--
-- @since 2.12.0.0
, connEscapeTableName :: EntityDef -> Text
-- ^ A function to extract and escape the name of the table corresponding
-- to the provided entity. PostgreSQL uses this to support schemas.
--
-- @since 2.12.0.0
, connEscapeRawName :: Text -> Text
-- ^ A function to escape raw DB identifiers. MySQL uses backticks, while
-- PostgreSQL uses quotes, and so on.
--
-- @since 2.12.0.0
, connNoLimit :: Text
, connRDBMS :: Text
-- ^ A tag displaying what database the 'SqlBackend' is for. Can be
-- used to differentiate features in downstream libraries for different
-- database backends.
, connLimitOffset :: (Int,Int) -> Text -> Text
-- ^ Attach a 'LIMIT/OFFSET' clause to a SQL query. Note that
-- LIMIT/OFFSET is problematic for performance, and indexed range
-- queries are the superior way to offer pagination.
, connLogFunc :: LogFunc
-- ^ A log function for the 'SqlBackend' to use.
}
type LogFunc = Loc -> LogSource -> LogLevel -> LogStr -> IO ()
|
