Database.PostgreSQL.Store.Errand

Errand

data ErrandError

Error during errand

Constructors

NoResult

No Result has been returned.

UserError String

A user has thrown an error.

ExecError ExecStatus ErrorCode ByteString ByteString ByteString

Query execution failed.

ParseError RowError

Result processing failed.

Instances

Eq ErrandError

Methods

(==) :: ErrandError -> ErrandError -> Bool

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

Show ErrandError

Methods

showsPrec :: Int -> ErrandError -> ShowS

show :: ErrandError -> String

showList :: [ErrandError] -> ShowS

Monoid ErrandError

Methods

mempty :: ErrandError

mappend :: ErrandError -> ErrandError -> ErrandError

mconcat :: [ErrandError] -> ErrandError

MonadError ErrandError Errand

Methods

throwError :: ErrandError -> Errand a

catchError :: Errand a -> (ErrandError -> Errand a) -> Errand a

data ErrorCode

Error codes

Constructors

UnknownErrorCause ByteString

IntegrityViolation

RestrictViolation

NotNullViolation

ForeignKeyViolation

UniqueViolation

CheckViolation

ExclusionViolation

Instances

Eq ErrorCode

Methods

(==) :: ErrorCode -> ErrorCode -> Bool

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

Show ErrorCode

Methods

showsPrec :: Int -> ErrorCode -> ShowS

show :: ErrorCode -> String

showList :: [ErrorCode] -> ShowS

data Errand a

An interaction with the database

Instances

Monad Errand

Methods

(>>=) :: Errand a -> (a -> Errand b) -> Errand b

(>>) :: Errand a -> Errand b -> Errand b

return :: a -> Errand a

fail :: String -> Errand a

Functor Errand

Methods

fmap :: (a -> b) -> Errand a -> Errand b

(<$) :: a -> Errand b -> Errand a

Applicative Errand

Methods

pure :: a -> Errand a

(<*>) :: Errand (a -> b) -> Errand a -> Errand b

(*>) :: Errand a -> Errand b -> Errand b

(<*) :: Errand a -> Errand b -> Errand a

Alternative Errand

Methods

empty :: Errand a

(<|>) :: Errand a -> Errand a -> Errand a

some :: Errand a -> Errand [a]

many :: Errand a -> Errand [a]

MonadIO Errand

Methods

liftIO :: IO a -> Errand a

MonadError ErrandError Errand

Methods

throwError :: ErrandError -> Errand a

catchError :: Errand a -> (ErrandError -> Errand a) -> Errand a

runErrand :: Connection -> Errand a -> IO (Either ErrandError a)

Run an errand.

Execute queries

execute :: ErrandQuery q Result => q r -> ErrandResult q Result

Execute the query and return its internal result.

execute' :: ErrandQuery q Int => q r -> ErrandResult q Int

Same as execute but instead of a Result it returns the number of affected rows.

query :: (Entity r, ErrandQuery q [r]) => q r -> ErrandResult q [r]

Execute a query and process its result set.

queryWith :: (ErrandQuery q [r], KnownNat n) => RowParser n r -> q r -> ErrandResult q [r]

Execute a query and process its result set using the provided RowParser.

Prepare statements

prepare :: PrepQuery a r -> Errand ()

Prepare a preparable query.

Transactions

beginTransaction :: Errand ()

Begin a transaction.

commitTransaction :: Errand ()

Commit transaction.

saveTransaction :: ByteString -> Errand ()

Create savepoint within transaction.

rollbackTransaction :: Errand ()

Roll back transaction.

rollbackTransactionTo :: ByteString -> Errand ()

Roll back to a specific savepoint.

withTransaction :: Errand a -> Errand ()

Do something within a transaction.

Helpers

class ErrandQuery q r where

Identifies q as a query object.

Minimal complete definition

executeWith

Associated Types

type ErrandResult q r

A type equal to Errand r or a function which will eventually yield a Errand r

Methods

executeWith :: (Result -> Errand r) -> q x -> ErrandResult q r

Execute the query described in q x and pass its Result to the given function.

Instances

ErrandQuery Query r

Associated Types

type ErrandResult (Query :: * -> *) r :: *

Methods

executeWith :: (Result -> Errand r) -> Query x -> ErrandResult Query r

ErrandQuery Statement r

Associated Types

type ErrandResult (Statement :: * -> *) r :: *

Methods

executeWith :: (Result -> Errand r) -> Statement x -> ErrandResult Statement r

WithTuple ts => ErrandQuery (PrepQuery ts) r

Associated Types

type ErrandResult (PrepQuery ts :: * -> *) r :: *

Methods

executeWith :: (Result -> Errand r) -> PrepQuery ts x -> ErrandResult (PrepQuery ts) r