A type that may be converted from a SQL type.
Methods
fromField :: FieldParser aConvert a SQL value to a Haskell value.
Returns a list of exceptions if the conversion fails. In the case of library instances, this will usually be a single ResultError, but may be a
UnicodeException.Implementations of fromField should not retain any references to the Field nor the ByteString arguments after the result has been evaluated to WHNF. Such a reference causes the entire
LibPQ.to be retained.PQ.ResultFor example, the instance for ByteString uses copy to avoid such a reference, and that using bytestring functions such as drop and takeWhile alone will also trigger this memory leak.
Instances24FromField, …
FromField ByteStringDefined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField ByteStringDefined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField SQLDataDefined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField IntegerDefined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField Int16Defined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField Int32Defined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField Int64Defined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField Int8Defined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField Word16Defined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField Word32Defined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField Word64Defined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField Word8Defined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField BoolDefined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField DoubleDefined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField FloatDefined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField IntDefined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField WordDefined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField NullDefined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField TextDefined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField TextDefined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField DayDefined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField UTCTimeDefined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField [Char]Defined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromFieldFromField a => FromField (Maybe a)Defined in sqlite-simple-0.4.19.0 · Database.SQLite.Simple.FromField