Genesis.Persist

Connecting to PostgreSQL

The bindings in this section are re-exported from Genesis.Persist.Base.

data PostgresOptions

Connection options needed to connect to PostgreSQL. You can use postgresOptions to parse these options from the environment.

Constructors

PostgresOptions

Fields

• host :: Text
• port :: Int
• user :: Text
• dbName :: Text
• password :: Text

Instances

Eq PostgresOptions

Methods

(==) :: PostgresOptions -> PostgresOptions -> Bool

(/=) :: PostgresOptions -> PostgresOptions -> Bool

Show PostgresOptions

Methods

showsPrec :: Int -> PostgresOptions -> ShowS

show :: PostgresOptions -> String

showList :: [PostgresOptions] -> ShowS

Generic PostgresOptions

Associated Types

type Rep PostgresOptions :: * -> *

Methods

from :: PostgresOptions -> Rep PostgresOptions x

to :: Rep PostgresOptions x -> PostgresOptions

type Rep PostgresOptions

type Rep PostgresOptions = D1 (MetaData "PostgresOptions" "Genesis.Persist.Base" "genesis-0.1.0.0-3wIsLyrVl5kDHiB4PjhTwy" False) (C1 (MetaCons "PostgresOptions" PrefixI True) ((:*:) ((:*:) (S1 (MetaSel (Just Symbol "host") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Text)) (S1 (MetaSel (Just Symbol "port") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Int))) ((:*:) (S1 (MetaSel (Just Symbol "user") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Text)) ((:*:) (S1 (MetaSel (Just Symbol "dbName") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Text)) (S1 (MetaSel (Just Symbol "password") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Text))))))

postgresOptions :: (AsEmpty e, AsUnread e, AsUnset e) => Parser e PostgresOptions

An envparse Parser that parses PostgresOptions from the environment, looking for the environment variables PG_HOST, PG_PORT, PG_USER, PG_USER, PG_DB_NAME, and PG_PASSWORD. All of them are optional except for PG_DB_NAME.

withPostgresqlPool

Arguments

:: (MonadBaseControl IO m, MonadLogger m)

=> PostgresOptions

Options to connect to the database.

-> Int

Number of connections to be kept open in the pool.

-> (Pool SqlBackend -> m a)

Action to be executed that uses the connection pool.

-> m a

Like withPostgresqlPool from Database.Persist.Postgresql, except using PostgresOptions.

withPostgresqlConn :: (MonadBaseControl IO m, MonadLogger m) => PostgresOptions -> (SqlBackend -> m a) -> m a

Like withPostgresqlConn from Database.Persist.Postgresql, except using PostgresOptions.

Compiling and running SQL migrations

The bindings in this section are re-exported from Genesis.Persist.Migrate.

runMigrations :: FilePath -> Q Exp

Compiles a set of .sql files in a particular directory into your application, then runs them against a database at runtime. This function is implemented with Template Haskell so that it can read the migration files at compile-time, but it semantically has the type (MonadLogger m, MonadSqlPersist m) => FilePath -> m (). Migrations will be executed in order based on their filename, according to sort.

The FilePath provided should be relative to your project root, and it will detect all files within the immediate directory (that is, not in subdirectories) with the suffix .sql.

Example:

 main :: IO ()
 main = runStderrLoggingT $ withSqliteConn ":memory:" (runSqlPersistT $(runMigrations "db/migrations"))