Safe Haskell	None
Language	Haskell2010

Hasql.Session

Contents

Synopsis

Documentation

A batch of actions to be executed in the context of a database connection.

Instances

Monad Session #
Instance details Defined in Hasql.Private.Session Methods (>>=) :: Session a -> (a -> Session b) -> Session b # (>>) :: Session a -> Session b -> Session b # return :: a -> Session a # fail :: String -> Session a #
Functor Session #
Instance details Defined in Hasql.Private.Session Methods fmap :: (a -> b) -> Session a -> Session b # (<$) :: a -> Session b -> Session a #
Applicative Session #
Instance details Defined in Hasql.Private.Session Methods pure :: a -> Session a # (<>) :: Session (a -> b) -> Session a -> Session b # liftA2 :: (a -> b -> c) -> Session a -> Session b -> Session c # (>) :: Session a -> Session b -> Session b # (<*) :: Session a -> Session b -> Session a #
MonadIO Session #
Instance details Defined in Hasql.Private.Session Methods liftIO :: IO a -> Session a #
MonadError QueryError Session #
Instance details Defined in Hasql.Private.Session Methods throwError :: QueryError -> Session a # catchError :: Session a -> (QueryError -> Session a) -> Session a #

Possibly a multi-statement query, which however cannot be parameterized or prepared, nor can any results of it be collected.

statement :: params -> Statement params result -> Session result #

Parameters and a specification of a parametric single-statement query to apply them to.

Execution

Executes a bunch of commands on the provided connection.

An error during the execution of a query. Comes packed with the query template and a textual representation of the provided params.

Constructors

Instances

Eq QueryError #
Instance details Defined in Hasql.Private.Errors Methods (==) :: QueryError -> QueryError -> Bool # (/=) :: QueryError -> QueryError -> Bool #
Show QueryError #
Instance details Defined in Hasql.Private.Errors Methods showsPrec :: Int -> QueryError -> ShowS # show :: QueryError -> String # showList :: [QueryError] -> ShowS #
MonadError QueryError Session #
Instance details Defined in Hasql.Private.Session Methods throwError :: QueryError -> Session a # catchError :: Session a -> (QueryError -> Session a) -> Session a #

An error of some command in the session.

Constructors

ClientError (Maybe ByteString)	An error on the client-side, with a message generated by the "libpq" library. Usually indicates problems with connection.
ResultError ResultError	Some error with a command result.

Instances

Eq CommandError #
Instance details Defined in Hasql.Private.Errors Methods (==) :: CommandError -> CommandError -> Bool # (/=) :: CommandError -> CommandError -> Bool #
Show CommandError #
Instance details Defined in Hasql.Private.Errors Methods showsPrec :: Int -> CommandError -> ShowS # show :: CommandError -> String # showList :: [CommandError] -> ShowS #

An error with a command result.

Constructors

ServerError ByteString ByteString (Maybe ByteString) (Maybe ByteString)	An error reported by the DB. Consists of the following: Code, message, details, hint. Code. The SQLSTATE code for the error. It's recommended to use the "postgresql-error-codes" package to work with those. Message. The primary human-readable error message (typically one line). Always present. Details. An optional secondary error message carrying more detail about the problem. Might run to multiple lines. Hint. An optional suggestion on what to do about the problem. This is intended to differ from detail in that it offers advice (potentially inappropriate) rather than hard facts. Might run to multiple lines.
UnexpectedResult Text	The database returned an unexpected result. Indicates an improper statement or a schema mismatch.
RowError Int RowError	An error of the row reader, preceded by the index of the row.
UnexpectedAmountOfRows Int	An unexpected amount of rows.

Instances

Eq ResultError #
Instance details Defined in Hasql.Private.Errors Methods (==) :: ResultError -> ResultError -> Bool # (/=) :: ResultError -> ResultError -> Bool #
Show ResultError #
Instance details Defined in Hasql.Private.Errors Methods showsPrec :: Int -> ResultError -> ShowS # show :: ResultError -> String # showList :: [ResultError] -> ShowS #

An error during the decoding of a specific row.

Constructors

EndOfInput	Appears on the attempt to parse more columns than there are in the result.
UnexpectedNull	Appears on the attempt to parse a `NULL` as some value.
ValueError Text	Appears when a wrong value parser is used. Comes with the error details.

Instances

Eq RowError #
Instance details Defined in Hasql.Private.Errors Methods (==) :: RowError -> RowError -> Bool # (/=) :: RowError -> RowError -> Bool #
Show RowError #
Instance details Defined in Hasql.Private.Errors Methods showsPrec :: Int -> RowError -> ShowS # show :: RowError -> String # showList :: [RowError] -> ShowS #