Database.Persist.Sql.Types.Internal

Documentation

class HasPersistBackend backend where

Class which allows the plucking of a BaseBackend backend from some larger type. For example, instance HasPersistBackend (SqlReadBackend, Int) where type BaseBackend (SqlReadBackend, Int) = SqlBackend persistBackend = unSqlReadBackend . fst

Minimal complete definition

persistBackend

Associated Types

type BaseBackend backend

Methods

persistBackend :: backend -> BaseBackend backend

Instances

HasPersistBackend SqlWriteBackend

Associated Types

type BaseBackend SqlWriteBackend :: *

Methods

persistBackend :: SqlWriteBackend -> BaseBackend SqlWriteBackend

HasPersistBackend SqlReadBackend

Associated Types

type BaseBackend SqlReadBackend :: *

Methods

persistBackend :: SqlReadBackend -> BaseBackend SqlReadBackend

HasPersistBackend SqlBackend

Associated Types

type BaseBackend SqlBackend :: *

Methods

persistBackend :: SqlBackend -> BaseBackend SqlBackend

class HasPersistBackend backend => IsPersistBackend backend where

Class which witnesses that backend is essentially the same as BaseBackend backend. That is, they're isomorphic and backend is just some wrapper over BaseBackend backend.

Minimal complete definition

mkPersistBackend

Methods

mkPersistBackend :: BaseBackend backend -> backend

This function is how we actually construct and tag a backend as having read or write capabilities. It should be used carefully and only when actually constructing a backend. Careless use allows us to accidentally run a write query against a read-only database.

Instances

IsPersistBackend SqlWriteBackend

Methods

mkPersistBackend :: BaseBackend SqlWriteBackend -> SqlWriteBackend

IsPersistBackend SqlReadBackend

Methods

mkPersistBackend :: BaseBackend SqlReadBackend -> SqlReadBackend

IsPersistBackend SqlBackend

Methods

mkPersistBackend :: BaseBackend SqlBackend -> SqlBackend

data SqlReadBackend

An SQL backend which can only handle read queries

Instances

IsPersistBackend SqlReadBackend

Methods

mkPersistBackend :: BaseBackend SqlReadBackend -> SqlReadBackend

HasPersistBackend SqlReadBackend

Associated Types

type BaseBackend SqlReadBackend :: *

Methods

persistBackend :: SqlReadBackend -> BaseBackend SqlReadBackend

data BackendKey SqlReadBackend

data BackendKey SqlReadBackend = SqlReadBackendKey {

• unSqlReadBackendKey :: Int64

}

type BaseBackend SqlReadBackend

type BaseBackend SqlReadBackend = SqlBackend

data SqlWriteBackend

An SQL backend which can handle read or write queries

Instances

IsPersistBackend SqlWriteBackend

Methods

mkPersistBackend :: BaseBackend SqlWriteBackend -> SqlWriteBackend

HasPersistBackend SqlWriteBackend

Associated Types

type BaseBackend SqlWriteBackend :: *

Methods

persistBackend :: SqlWriteBackend -> BaseBackend SqlWriteBackend

data BackendKey SqlWriteBackend

data BackendKey SqlWriteBackend = SqlWriteBackendKey {

• unSqlWriteBackendKey :: Int64

}

type BaseBackend SqlWriteBackend

type BaseBackend SqlWriteBackend = SqlBackend

readToUnknown :: Monad m => ReaderT SqlReadBackend m a -> ReaderT SqlBackend m a

Useful for running a read query against a backend with unknown capabilities.

readToWrite :: Monad m => ReaderT SqlReadBackend m a -> ReaderT SqlWriteBackend m a

Useful for running a read query against a backend with read and write capabilities.

writeToUnknown :: Monad m => ReaderT SqlWriteBackend m a -> ReaderT SqlBackend m a

Useful for running a write query against an untagged backend with unknown capabilities.

type LogFunc = Loc -> LogSource -> LogLevel -> LogStr -> IO ()

data InsertSqlResult

Constructors

ISRSingle Text

ISRInsertGet Text Text

ISRManyKeys Text [PersistValue]

data Statement

Constructors

Statement

Fields

• stmtFinalize :: IO ()
• stmtReset :: IO ()
• stmtExecute :: [PersistValue] -> IO Int64
• stmtQuery :: forall m. MonadIO m => [PersistValue] -> Acquire (ConduitM () [PersistValue] m ())

data SqlBackend

Constructors

SqlBackend

Fields

• connPrepare :: Text -> IO Statement
• connInsertSql :: EntityDef -> [PersistValue] -> InsertSqlResult

  table name, column names, id name, either 1 or 2 statements to run

• connInsertManySql :: Maybe (EntityDef -> [[PersistValue]] -> InsertSqlResult)

  SQL for inserting many rows and returning their primary keys, for backends that support this functioanlity. If Nothing, rows will be inserted one-at-a-time using connInsertSql.

• connUpsertSql :: Maybe (EntityDef -> Text -> Text)

  Some databases support performing UPSERT _and_ RETURN entity in a single call.

  This field when set will be used to generate the UPSERT+RETURN sql given * an entity definition * updates to be run on unique key(s) collision

  When left as Nothing, we find the unique key from entity def before * trying to fetch an entity by said key * perform an update when result found, else issue an insert * return new entity from db

  Since: 2.6

• connPutManySql :: Maybe (EntityDef -> Int -> Text)

  Some databases support performing bulk UPSERT, specifically "insert or replace many records" in a single call.

  This field when set, given * an entity definition * number of records to be inserted should produce a PUT MANY sql with placeholders for records

  When left as Nothing, we default to using defaultPutMany.

  Since: 2.8.1

• connStmtMap :: IORef (Map Text Statement)
• connClose :: IO ()
• connMigrateSql :: [EntityDef] -> (Text -> IO Statement) -> EntityDef -> IO (Either [Text] [(Bool, Text)])
• connBegin :: (Text -> IO Statement) -> IO ()
• connCommit :: (Text -> IO Statement) -> IO ()
• connRollback :: (Text -> IO Statement) -> IO ()
• connEscapeName :: DBName -> Text
• connNoLimit :: Text
• connRDBMS :: Text
• connLimitOffset :: (Int, Int) -> Bool -> Text -> Text
• connLogFunc :: LogFunc
• connMaxParams :: Maybe Int

  Some databases (probably only Sqlite) have a limit on how many question-mark parameters may be used in a statement

  Since: 2.6.1

Instances

IsPersistBackend SqlBackend

Methods

mkPersistBackend :: BaseBackend SqlBackend -> SqlBackend

HasPersistBackend SqlBackend

Associated Types

type BaseBackend SqlBackend :: *

Methods

persistBackend :: SqlBackend -> BaseBackend SqlBackend

data BackendKey SqlBackend

data BackendKey SqlBackend = SqlBackendKey {

• unSqlBackendKey :: Int64

}

type BaseBackend SqlBackend

type BaseBackend SqlBackend = SqlBackend

type SqlBackendCanRead backend = (BackendCompatible SqlBackend backend, PersistQueryRead backend, PersistStoreRead backend, PersistUniqueRead backend)

A constraint synonym which witnesses that a backend is SQL and can run read queries.

type SqlBackendCanWrite backend = (SqlBackendCanRead backend, PersistQueryWrite backend, PersistStoreWrite backend, PersistUniqueWrite backend)

A constraint synonym which witnesses that a backend is SQL and can run read and write queries.

type SqlReadT m a = forall backend. SqlBackendCanRead backend => ReaderT backend m a

Like SqlPersistT but compatible with any SQL backend which can handle read queries.

type SqlWriteT m a = forall backend. SqlBackendCanWrite backend => ReaderT backend m a

Like SqlPersistT but compatible with any SQL backend which can handle read and write queries.

type IsSqlBackend backend = (IsPersistBackend backend, BaseBackend backend ~ SqlBackend)

A backend which is a wrapper around SqlBackend.