Hasql.Session

Documentation

data Session a

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

Instances

MonadIO Session

Defined in Hasql.Session.Core

Methods

liftIO :: IO a -> Session a

Applicative Session

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

Defined in Hasql.Session.Core

Methods

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

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

Monad Session

Defined in Hasql.Session.Core

Methods

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

(>>) :: Session a -> Session b -> Session b

return :: a -> Session a

MonadError SessionError Session

Defined in Hasql.Session.Core

Methods

throwError :: SessionError -> Session a

catchError :: Session a -> (SessionError -> Session a) -> Session a

MonadReader Connection Session

Defined in Hasql.Session.Core

Methods

ask :: Session Connection

local :: (Connection -> Connection) -> Session a -> Session a

reader :: (Connection -> a) -> Session a

sql :: ByteString -> Session ()

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

Execute a statement by providing parameters to it.

pipeline :: Pipeline result -> Session result

Execute a pipeline.

Execution

run :: Session a -> Connection -> IO (Either SessionError a)

Executes a bunch of commands on the provided connection.

Errors

data SessionError

Error during execution of a session.

Constructors

QueryError

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

Fields

• ByteString

  SQL template.

• [Text]

  Parameters rendered as human-readable SQL literals.

• CommandError

  Error details.

PipelineError

Error during the execution of a pipeline.

Fields

• CommandError

  Error details.

Instances

Exception SessionError

Defined in Hasql.Errors

Methods

toException :: SessionError -> SomeException

fromException :: SomeException -> Maybe SessionError

displayException :: SessionError -> String

backtraceDesired :: SessionError -> Bool

Show SessionError

Defined in Hasql.Errors

Methods

showsPrec :: Int -> SessionError -> ShowS

show :: SessionError -> String

showList :: [SessionError] -> ShowS

Eq SessionError

Defined in Hasql.Errors

Methods

(==) :: SessionError -> SessionError -> Bool

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

MonadError SessionError Session

Defined in Hasql.Session.Core

Methods

throwError :: SessionError -> Session a

catchError :: Session a -> (SessionError -> Session a) -> Session a

data CommandError

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

Show CommandError

Defined in Hasql.Errors

Methods

showsPrec :: Int -> CommandError -> ShowS

show :: CommandError -> String

showList :: [CommandError] -> ShowS

Eq CommandError

Defined in Hasql.Errors

Methods

(==) :: CommandError -> CommandError -> Bool

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

data ResultError

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

Show ResultError

Defined in Hasql.Errors

Methods

showsPrec :: Int -> ResultError -> ShowS

show :: ResultError -> String

showList :: [ResultError] -> ShowS

Eq ResultError

Defined in Hasql.Errors

Methods

(==) :: ResultError -> ResultError -> Bool

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

data RowError

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

Show RowError

Defined in Hasql.Errors

Methods

showsPrec :: Int -> RowError -> ShowS

show :: RowError -> String

showList :: [RowError] -> ShowS

Eq RowError

Defined in Hasql.Errors

Methods

(==) :: RowError -> RowError -> Bool

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