Safe Haskell	Safe-Inferred
Language	Haskell2010

Hasql.Session

Contents

Synopsis

Documentation

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

Instances details

MonadIO Session Source #
Instance details Defined in Hasql.Session.Core Methods liftIO :: IO a -> Session a #
Applicative Session Source #
Instance details Defined in Hasql.Session.Core 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 #
Functor Session Source #
Instance details Defined in Hasql.Session.Core Methods fmap :: (a -> b) -> Session a -> Session b # (<$) :: a -> Session b -> Session a #
Monad Session Source #
Instance details Defined in Hasql.Session.Core Methods (>>=) :: Session a -> (a -> Session b) -> Session b # (>>) :: Session a -> Session b -> Session b # return :: a -> Session a #
MonadError QueryError Session Source #
Instance details Defined in Hasql.Session.Core Methods throwError :: QueryError -> Session a # catchError :: Session a -> (QueryError -> Session a) -> Session a #
MonadReader Connection Session Source #
Instance details Defined in Hasql.Session.Core Methods ask :: Session Connection # local :: (Connection -> Connection) -> Session a -> Session a # reader :: (Connection -> 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 Source #

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 details

Exception QueryError Source #
Instance details Defined in Hasql.Errors Methods toException :: QueryError -> SomeException # fromException :: SomeException -> Maybe QueryError # displayException :: QueryError -> String #
Show QueryError Source #
Instance details Defined in Hasql.Errors Methods showsPrec :: Int -> QueryError -> ShowS # show :: QueryError -> String # showList :: [QueryError] -> ShowS #
Eq QueryError Source #
Instance details Defined in Hasql.Errors Methods (==) :: QueryError -> QueryError -> Bool # (/=) :: QueryError -> QueryError -> Bool #
MonadError QueryError Session Source #
Instance details Defined in Hasql.Session.Core 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 details

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

An error with a command result.

Constructors

ServerError	An error reported by the DB.
Fields ByteString Code. The SQLSTATE code for the error. It's recommended to use <http://hackage.haskell.org/package/postgresql-error-codes the "postgresql-error-codes" package> to work with those. ByteString Message. The primary human-readable error message(typically one line). Always present. (Maybe ByteString) Details. An optional secondary error message carrying more detail about the problem. Might run to multiple lines. (Maybe ByteString) 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. (Maybe Int) Position. Error cursor position as an index into the original statement string. Positions are measured in characters not bytes.
UnexpectedResult Text	The database returned an unexpected result. Indicates an improper statement or a schema mismatch.
RowError Int Int RowError	An error of the row reader, preceded by the indexes of the row and column.
UnexpectedAmountOfRows Int	An unexpected amount of rows.

Instances details

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

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 details

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