Database.PostgreSQL.Simple.Errors

| Module for parsing errors from postgresql error messages. Currently only parses integrity violation errors (class 23).

Note: Success of parsing may depend on language settings.

Documentation

data ConstraintViolation

Constructors

NotNullViolation ByteString

The field is a column name

ForeignKeyViolation ByteString ByteString

Table name and name of violated constraint

UniqueViolation ByteString

Name of violated constraint

CheckViolation ByteString ByteString

Relation name (usually table), constraint name

ExclusionViolation ByteString

Name of the exclusion violation constraint

Instances

Eq ConstraintViolation

Methods

(==) :: ConstraintViolation -> ConstraintViolation -> Bool

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

Ord ConstraintViolation

Methods

compare :: ConstraintViolation -> ConstraintViolation -> Ordering

(<) :: ConstraintViolation -> ConstraintViolation -> Bool

(<=) :: ConstraintViolation -> ConstraintViolation -> Bool

(>) :: ConstraintViolation -> ConstraintViolation -> Bool

(>=) :: ConstraintViolation -> ConstraintViolation -> Bool

max :: ConstraintViolation -> ConstraintViolation -> ConstraintViolation

min :: ConstraintViolation -> ConstraintViolation -> ConstraintViolation

Show ConstraintViolation

Methods

showsPrec :: Int -> ConstraintViolation -> ShowS

show :: ConstraintViolation -> String

showList :: [ConstraintViolation] -> ShowS

Exception ConstraintViolation

Methods

toException :: ConstraintViolation -> SomeException

fromException :: SomeException -> Maybe ConstraintViolation

displayException :: ConstraintViolation -> String

constraintViolation :: SqlError -> Maybe ConstraintViolation

Tries to convert SqlError to ConstrainViolation, checks sqlState and succeedes only if able to parse sqlErrorMsg.

createUser = handleJust constraintViolation handler $ execute conn ...
  where
    handler (UniqueViolation "user_login_key") = ...
    handler _ = ...

constraintViolationE :: SqlError -> Maybe (SqlError, ConstraintViolation)

Like constraintViolation, but also packs original SqlError.

createUser = handleJust constraintViolationE handler $ execute conn ...
  where
    handler (_, UniqueViolation "user_login_key") = ...
    handler (e, _) = throwIO e

catchViolation :: (SqlError -> ConstraintViolation -> IO a) -> IO a -> IO a

Catches SqlError, tries to convert to ConstraintViolation, re-throws on fail. Provides alternative interface to handleJust

createUser = catchViolation catcher $ execute conn ...
  where
    catcher _ (UniqueViolation "user_login_key") = ...
    catcher e _ = throwIO e

isSerializationError :: SqlError -> Bool

isNoActiveTransactionError :: SqlError -> Bool

isFailedTransactionError :: SqlError -> Bool