| Copyright | (c) 2012-2013 Leonid Onokhov Joey Adams |
|---|---|
| License | BSD3 |
| Maintainer | Leon P Smith <leon@melding-monads.com> |
| Stability | experimental |
| Safe Haskell | None |
| Language | Haskell2010 |
Database.PostgreSQL.Simple.Errors
Description
| 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.
Synopsis
- data ConstraintViolation
- constraintViolation :: SqlError -> Maybe ConstraintViolation
- constraintViolationE :: SqlError -> Maybe ( SqlError , ConstraintViolation )
- catchViolation :: ( SqlError -> ConstraintViolation -> IO a) -> IO a -> IO a
- isSerializationError :: SqlError -> Bool
- isNoActiveTransactionError :: SqlError -> Bool
- isFailedTransactionError :: SqlError -> Bool
Documentation
data ConstraintViolation Source #
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
constraintViolation :: SqlError -> Maybe ConstraintViolation Source #
Tries to convert
SqlError
to
ConstrainViolation
, checks sqlState and
succeeds only if able to parse sqlErrorMsg.
createUser = handleJust constraintViolation handler $ execute conn ...
where
handler (UniqueViolation "user_login_key") = ...
handler _ = ...
constraintViolationE :: SqlError -> Maybe ( SqlError , ConstraintViolation ) Source #
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 Source #
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 Source #