Rewrite everything to use XmlImport/DbImport classes making things much more easy...

[dead/htsn-import.git] / src / TSN / DbImport.hs

diff --git a/src/TSN/DbImport.hs b/src/TSN/DbImport.hs
index 83092558bef6c2b52bd9bad479c02677c1b9bf51..e0dd1349a1469cc7ead734923a2a5d027aea9007 100644 (file)
--- a/src/TSN/DbImport.hs
+++ b/src/TSN/DbImport.hs
@@ -2,46 +2,33 @@
 module TSN.DbImport
 where
 
-import Control.Monad.IO.Class ( MonadIO, liftIO )
-import Database.Groundhog (
-  defaultMigrationLogger,
-  insert,
-  migrate,
-  runMigration )
-import Database.Groundhog.Core ( PersistBackend, PersistEntity )
-import Network.Services.TSN.Report ( report_error )
-import Text.XML.HXT.Core (
-  XmlPickler,
-  XmlTree,
-  unpickleDoc,
-  xpickle )
+import Control.Monad.IO.Class ( MonadIO )
+import Database.Groundhog.Core ( PersistBackend )
+
+import TSN.XmlImport ( XmlImport(..) )
+
+-- | The type that will be returned from every file import attempt.
+--
+data ImportResult =
+  ImportFailed String -- ^ Failure with an error message.
+    | ImportSkipped String -- ^ We processed the file, but didn't import it.
+                           --   The reason is contained in the second field.
+    | ImportSucceeded      -- ^ We did import records.
+    | ImportUnsupported String -- ^ We didn't know how to process this file.
+                               --   The second field should contain info.
 
 -- | Instances of this type know how to insert themselves into a
 --   Groundhog database.
+--
 class DbImport a where
-  dbimport :: (MonadIO m, PersistBackend m)
-           => a
-           -> XmlTree
-           -> m (Maybe Int)
+  -- | 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@.
+  dbmigrate :: (MonadIO m, PersistBackend m) => a -> m ()
 
--- | We put the 'Configuration' and 'XmlTree' arguments last so that
--- it's easy to eta reduce all of the import_foo functions that call
--- this.
---
-import_generic :: (XmlPickler a, MonadIO m, PersistEntity b, PersistBackend m)
-               => (a -> [b]) -- ^ listings getter
-               -> b          -- ^ Dummy Listing instance needed for 'migrate'
-               -> XmlTree
-               -> m (Maybe Int) -- ^ Return the number of records inserted.
-import_generic g dummy xml = do
-  runMigration defaultMigrationLogger $ migrate dummy
-  let root_element = unpickleDoc xpickle xml
-  case root_element of
-    Nothing -> do
-      let msg = "Could not unpickle document in import_generic."
-      liftIO $ report_error msg
-      return Nothing
-    Just elt  -> do
-      ids <- mapM insert (g elt)
-      return $ Just (length ids)
+dbimport_generic :: (XmlImport a, MonadIO m, PersistBackend m)
+                 => a
+                 -> m ImportResult
+dbimport_generic x = insert_xml x >> return ImportSucceeded