| Copyright | (c) 2011 MailRank Inc. |
|---|---|
| License | BSD3 |
| Maintainer | José Lorenzo Rodríguez |
| Stability | experimental |
| Portability | portable |
| Safe Haskell | None |
| Language | Haskell2010 |
Database.MySQL.Nem.Result
Description
The Result typeclass, for converting a single value in a row
returned by a SQL query into a more useful Haskell representation.
A Haskell numeric type is considered to be compatible with all
MySQL numeric types that are less accurate than it. For instance,
the Haskell Double type is compatible with the MySQL Long type
because it can represent a Long exactly. On the other hand, since
a Double might lose precision if representing a LongLong, the
two are not considered compatible.
Synopsis
- data ResultError
- = Incompatible { }
- | ConversionFailed { }
- class Result a where
- convert :: ColumnDef -> MySQLValue -> a
Documentation
data ResultError #
Exception thrown if conversion from a SQL value to a Haskell value fails.
Constructors
| Incompatible | |
Fields
| |
| ConversionFailed | |
Fields
| |
Instances
| Eq ResultError # | |
Defined in Database.MySQL.Nem.Result | |
| Show ResultError # | |
Defined in Database.MySQL.Nem.Result Methods showsPrec :: Int -> ResultError -> ShowS # show :: ResultError -> String # showList :: [ResultError] -> ShowS # | |
| Exception ResultError # | |
Defined in Database.MySQL.Nem.Result Methods toException :: ResultError -> SomeException # fromException :: SomeException -> Maybe ResultError # displayException :: ResultError -> String # | |
A type that may be converted from a SQL type.
Methods
convert :: ColumnDef -> MySQLValue -> a #