-- | Definition of the DbImport typeclass.
+--
+-- When we parse an XML tree, there are two functions that we would
+-- like to call on the result independent of its type. First, we
+-- would like to be able to run the database migrations for that
+-- type. The migrations are kept separate from insertion because, at
+-- some later point, it make make sense to disable automatic
+-- migrations.
+--
+-- Next we want to import the thing.
+--
+-- Neither of these should depend on the type -- we should just be
+-- able to call 'dbmigrate' followed by 'dbimport' on the
+-- datastructure and have the right thing happen. That is the
+-- purpose of the 'DbImport' typeclass. It allows the XML types to
+-- define their own \"migrate me\" and \"insert me\" functions that
+-- the rest of the application doesn't have to care about.
+--
module TSN.DbImport (
DbImport(..),
ImportResult(..),
- dbimport_generic,
run_dbmigrate )
where
-- System imports
import Control.Monad.IO.Class ( MonadIO )
-import Database.Groundhog (
- runMigration )
+import Database.Groundhog ( runMigration )
import Database.Groundhog.Core ( Migration, PersistBackend )
import Network.Services.TSN.Report ( report_info )
--- Local imports
-import TSN.XmlImport ( XmlImport(..) )
-
-- | The type that will be returned from every file import attempt.
--
-- The second field should contain info.
--- | Instances of this type know how to insert themselves into a
--- Groundhog database.
+-- | Instances of this type know how to run their own database
+-- migrations and insert themselves into a database.
--
class DbImport a where
-- | Import an instance of type @a@.
dbimport :: (PersistBackend m) => a -> m ImportResult
-- | This must migrate *all* stuffs that can potentially be
- -- created/used by the type @a@.
+ -- created/used by the type @a@.
dbmigrate :: (MonadIO m, PersistBackend m) => a -> m ()
--- | The simplest possible implementation of 'dbimport', for types
--- which happen to be members of the XmlImport typeclass.
---
-dbimport_generic :: (XmlImport a, MonadIO m, PersistBackend m)
- => a
- -> m ImportResult
-dbimport_generic x = insert_xml x >> return ImportSucceeded
-
-
-- | A migration runner that will use our normal info reporting
-- mechanism.
+--
run_dbmigrate :: (MonadIO m, PersistBackend m) => Migration m -> m ()
run_dbmigrate =
runMigration pretty_migration_logger