HasId/Groundhog interop.
A class and some instances for HasId/Groundhog interoperation
database-id-groundhog
This package provides support for groundhog database interaction to database-id-class, in particular, the functions
toId :: DefaultKeyId a => DefaultKey a -> Id a
fromId :: DefaultKeyId a => Id a -> DefaultKey a
which convert back and forth between the Id and groundhog's DefaultKey representation according to the instances of the DefaultKeyId class.
It also includes the Template Haskell macro makeDefaultKeyIdInt64 which, given the Name of a datatype and the Name of the data constructor for its groundhog-generated key datatype (typically named the same as the type, with the suffix "Key"), produces an instance of DefaultKeyId in cases where the primary key is an Int64.
Similar to this, makeDefaultKeyIdSimple exists for cases where all that is required to go between DefaultKey a and IdData a is to remove (or put back) Groundhog's type-specific Key data constructor.
It also includes instances of PersistField and PrimitivePersistField for Id a.