Database.Persist.Sqlite

A sqlite backend for persistent.

Note: If you prepend WAL=off to your connection string, it will disable the write-ahead log. This functionality is now deprecated in favour of using SqliteConnectionInfo.

Documentation

withSqlitePool

Arguments

:: (MonadUnliftIO m, MonadLogger m, IsSqlBackend backend)

=> Text

-> Int

number of connections to open

-> (Pool backend -> m a)

-> m a

Run the given action with a connection pool.

Like createSqlitePool, this should not be used with :memory:.

withSqlitePoolInfo

Arguments

:: (MonadUnliftIO m, MonadLogger m, IsSqlBackend backend)

=> SqliteConnectionInfo

-> Int

number of connections to open

-> (Pool backend -> m a)

-> m a

Run the given action with a connection pool.

Like createSqlitePool, this should not be used with :memory:.

Since: 2.6.2

withSqliteConn :: (MonadUnliftIO m, MonadLogger m, IsSqlBackend backend) => Text -> (backend -> m a) -> m a

withSqliteConnInfo :: (MonadUnliftIO m, MonadLogger m, IsSqlBackend backend) => SqliteConnectionInfo -> (backend -> m a) -> m a

Since: 2.6.2

createSqlitePool :: (MonadLogger m, MonadUnliftIO m, IsSqlBackend backend) => Text -> Int -> m (Pool backend)

Create a pool of SQLite connections.

Note that this should not be used with the :memory: connection string, as the pool will regularly remove connections, destroying your database. Instead, use withSqliteConn.

createSqlitePoolFromInfo :: (MonadLogger m, MonadUnliftIO m, IsSqlBackend backend) => SqliteConnectionInfo -> Int -> m (Pool backend)

Create a pool of SQLite connections.

Note that this should not be used with the :memory: connection string, as the pool will regularly remove connections, destroying your database. Instead, use withSqliteConn.

Since: 2.6.2

module Database.Persist.Sql

data SqliteConf

Information required to setup a connection pool.

Constructors

SqliteConf

Fields

• sqlDatabase :: Text
• sqlPoolSize :: Int

SqliteConfInfo

Fields

• sqlConnInfo :: SqliteConnectionInfo
• sqlPoolSize :: Int

Instances

Show SqliteConf

Defined in Database.Persist.Sqlite

Methods

showsPrec :: Int -> SqliteConf -> ShowS

show :: SqliteConf -> String

showList :: [SqliteConf] -> ShowS

FromJSON SqliteConf

Defined in Database.Persist.Sqlite

Methods

parseJSON :: Value -> Parser SqliteConf

parseJSONList :: Value -> Parser [SqliteConf]

PersistConfig SqliteConf

Defined in Database.Persist.Sqlite

Associated Types

type PersistConfigBackend SqliteConf :: (Type -> Type) -> Type -> Type

type PersistConfigPool SqliteConf :: Type

Methods

loadConfig :: Value -> Parser SqliteConf

applyEnv :: SqliteConf -> IO SqliteConf

createPoolConfig :: SqliteConf -> IO (PersistConfigPool SqliteConf)

runPool :: MonadUnliftIO m => SqliteConf -> PersistConfigBackend SqliteConf m a -> PersistConfigPool SqliteConf -> m a

type PersistConfigPool SqliteConf

Defined in Database.Persist.Sqlite

type PersistConfigPool SqliteConf = ConnectionPool

type PersistConfigBackend SqliteConf

Defined in Database.Persist.Sqlite

type PersistConfigBackend SqliteConf = SqlPersistT

data SqliteConnectionInfo

Information required to connect to a sqlite database. We export lenses instead of fields to avoid being limited to the current implementation.

Since: 2.6.2

Instances

Show SqliteConnectionInfo

Defined in Database.Persist.Sqlite

Methods

showsPrec :: Int -> SqliteConnectionInfo -> ShowS

show :: SqliteConnectionInfo -> String

showList :: [SqliteConnectionInfo] -> ShowS

FromJSON SqliteConnectionInfo

Defined in Database.Persist.Sqlite

Methods

parseJSON :: Value -> Parser SqliteConnectionInfo

parseJSONList :: Value -> Parser [SqliteConnectionInfo]

mkSqliteConnectionInfo :: Text -> SqliteConnectionInfo

Creates a SqliteConnectionInfo from a connection string, with the default settings.

Since: 2.6.2

sqlConnectionStr :: Lens' SqliteConnectionInfo Text

walEnabled :: Lens' SqliteConnectionInfo Bool

fkEnabled :: Lens' SqliteConnectionInfo Bool

extraPragmas :: Lens' SqliteConnectionInfo [Text]

runSqlite

Arguments

:: (MonadUnliftIO m, IsSqlBackend backend)

=> Text

connection string

-> ReaderT backend (NoLoggingT (ResourceT m)) a

database action

-> m a

A convenience helper which creates a new database connection and runs the given block, handling MonadResource and MonadLogger requirements. Note that all log messages are discarded.

Since: 1.1.4

runSqliteInfo

Arguments

:: (MonadUnliftIO m, IsSqlBackend backend)

=> SqliteConnectionInfo

-> ReaderT backend (NoLoggingT (ResourceT m)) a

database action

-> m a

A convenience helper which creates a new database connection and runs the given block, handling MonadResource and MonadLogger requirements. Note that all log messages are discarded.

Since: 2.6.2

wrapConnection :: IsSqlBackend backend => Connection -> LogFunc -> IO backend

Wrap up a raw Connection as a Persistent SQL Connection.

Example usage

{-# LANGUAGE GADTs #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE QuasiQuotes #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}

import Control.Monad.IO.Class  (liftIO)
import Database.Persist
import Database.Sqlite
import Database.Persist.Sqlite
import Database.Persist.TH

share [mkPersist sqlSettings, mkMigrate "migrateAll"] [persistLowerCase|
Person
  name String
  age Int Maybe
  deriving Show
|]

main :: IO ()
main = do
  conn <- open "/home/sibi/test.db"
  (backend :: SqlBackend) <- wrapConnection conn (\_ _ _ _ -> return ())
  flip runSqlPersistM backend $ do
         runMigration migrateAll
         insert_ $ Person "John doe" $ Just 35
         insert_ $ Person "Hema" $ Just 36
         (pers :: [Entity Person]) <- selectList [] []
         liftIO $ print pers
  close' backend

On executing it, you get this output:

Migrating: CREATE TABLE "person"("id" INTEGER PRIMARY KEY,"name" VARCHAR NOT NULL,"age" INTEGER NULL)
[Entity {entityKey = PersonKey {unPersonKey = SqlBackendKey {unSqlBackendKey = 1}}, entityVal = Person {personName = "John doe", personAge = Just 35}},Entity {entityKey = PersonKey {unPersonKey = SqlBackendKey {unSqlBackendKey = 2}}, entityVal = Person {personName = "Hema", personAge = Just 36}}]

Since: 1.1.5

wrapConnectionInfo :: IsSqlBackend backend => SqliteConnectionInfo -> Connection -> LogFunc -> IO backend

Wrap up a raw Connection as a Persistent SQL Connection, allowing full control over WAL and FK constraints.

Since: 2.6.2

mockMigration :: Migration -> IO ()

Mock a migration even when the database is not present. This function performs the same functionality of printMigration with the difference that an actual database isn't needed for it.

retryOnBusy :: (MonadUnliftIO m, MonadLogger m) => m a -> m a

Retry if a Busy is thrown, following an exponential backoff strategy.

Since: 2.9.3

waitForDatabase :: (MonadUnliftIO m, MonadLogger m, IsSqlBackend backend, BackendCompatible SqlBackend backend) => ReaderT backend m ()

Wait until some noop action on the database does not return an ErrorBusy. See retryOnBusy.

Since: 2.9.3