Safe Haskell	Safe-Inferred
Language	Haskell2010

Relocant.DB

Description

This module manages PostgreSQL connections and relocant's DB schema.

Synopsis

data ConnectionString
data Table
defaultTable :: Table
connect :: ConnectionString -> Table -> IO Connection
init :: Table -> Connection -> IO ()
withLock :: Table -> Connection -> IO a -> IO a
withTryLock :: Table -> Connection -> (Bool -> IO a) -> IO a
lock :: Table -> Connection -> IO ()
tryLock :: Table -> Connection -> IO Bool
unlock :: Table -> Connection -> IO Bool
dumpSchema :: Table -> IO ()

Documentation

data ConnectionString Source #

PostgreSQL connection string. (This is a newtype over ByteString)

for syntax, see: https://hackage.haskell.org/package/postgresql-simple/docs/Database-PostgreSQL-Simple.html#v:connectPostgreSQL

Instances

Instances details

ToJSON ConnectionString Source #
Instance details Defined in Relocant.DB Methods toJSON :: ConnectionString -> Value # toEncoding :: ConnectionString -> Encoding # toJSONList :: [ConnectionString] -> Value # toEncodingList :: [ConnectionString] -> Encoding #
IsString ConnectionString Source #
Instance details Defined in Relocant.DB Methods fromString :: String -> ConnectionString #
Show ConnectionString Source #
Instance details Defined in Relocant.DB Methods showsPrec :: Int -> ConnectionString -> ShowS # show :: ConnectionString -> String # showList :: [ConnectionString] -> ShowS #
Eq ConnectionString Source #
Instance details Defined in Relocant.DB Methods (==) :: ConnectionString -> ConnectionString -> Bool # (/=) :: ConnectionString -> ConnectionString -> Bool #

data Table Source #

relocant's migration table name.

Instances

Instances details

ToJSON Table Source #
Instance details Defined in Relocant.DB.Table Methods toJSON :: Table -> Value # toEncoding :: Table -> Encoding # toJSONList :: [Table] -> Value # toEncodingList :: [Table] -> Encoding #
IsString Table Source #
Instance details Defined in Relocant.DB.Table Methods fromString :: String -> Table #
Show Table Source #	Return a `String` that can be `fromString`ed back to a `Table`.
Instance details Defined in Relocant.DB.Table Methods showsPrec :: Int -> Table -> ShowS # show :: Table -> String # showList :: [Table] -> ShowS #
Eq Table Source #
Instance details Defined in Relocant.DB.Table Methods (==) :: Table -> Table -> Bool # (/=) :: Table -> Table -> Bool #
ToField Table Source #
Instance details Defined in Relocant.DB.Table Methods toField :: Table -> Action #

defaultTable :: Table Source #

The default table name, which is "public.relocant_migration".

connect :: ConnectionString -> Table -> IO Connection Source #

Connect to the DB using the given ConnectionString and initialize the migrations table.

Note: If you get your Connection from elsewhere, remember to call init yourself.

init :: Table -> Connection -> IO () Source #

Initialize the migrations table.

withLock :: Table -> Connection -> IO a -> IO a Source #

Use pg_advisory_{lock,unlock} to restrict access to the migrations table. The given table is used to generate the lock's ID, so that in the unlikely case where you have multiple migrations tables in your database you can lock them separately.

withTryLock :: Table -> Connection -> (Bool -> IO a) -> IO a Source #

A non-blocking version of withLock. True is passed to the callback if the lock was successfully acquired, False otherwise.

lock :: Table -> Connection -> IO () Source #

Use pg_advisory_lock to lock the database, restricting access to the migrations table. The given table is used to generate the lock's ID, so that in the unlikely case where you have multiple migrations tables in your database you can lock them separately.

tryLock :: Table -> Connection -> IO Bool Source #

A non-blocking version of lock. Returns True if the lock was successfully acquired, False otherwise.

unlock :: Table -> Connection -> IO Bool Source #

Use pg_advisory_unlock to unlock the database.

dumpSchema :: Table -> IO () Source #