Add Generic instance for TSN.Team.

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

diff --git a/src/TSN/Team.hs b/src/TSN/Team.hs
index 97e36475e59c14ea93c64a819e5b275b121bdd87..1fef0a3447a2afaa4bfb579d3434bee10421dc7d 100644 (file)
--- a/src/TSN/Team.hs
+++ b/src/TSN/Team.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE DeriveGeneric #-}
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE GADTs #-}
 {-# LANGUAGE QuasiQuotes #-}
@@ -13,18 +14,29 @@
 --   representation.
 --
 module TSN.Team (
+  HTeam(..),
+  FromXmlFkTeams(..),
   Team(..),
+  VTeam(..),
   -- * WARNING: these are private but exported to silence warnings
   TeamConstructor(..) )
 where
 
 -- System imports
 import Database.Groundhog () -- Required for some String instance
+import Database.Groundhog.Core ( PersistEntity(..) )
 import Database.Groundhog.TH (
   defaultCodegenConfig,
   groundhog,
   mkPersist )
+import qualified GHC.Generics as GHC ( Generic )
 
+-- Local imports
+import Generics ( Generic(..) )
+import Xml ( Child(..), Db(..) )
+
+
+-- * Team
 
 -- | The database representation of a team. The 'team_id' is a
 --   'String' field because some teams do in fact have ids like
@@ -40,8 +52,29 @@ data Team =
                                   --   don't have them for some teams.
     name :: Maybe String -- ^ Some teams don't even have names!
     }
-  deriving (Eq, Show)
+  deriving (Eq, GHC.Generic, Show)
+
+-- | Needed for 'Generics.to_tuple'.
+--
+instance Generic Team
 
+-- * VTeam / HTeam
+
+-- | A wrapper around 'Team' that lets us distinguish between home and
+--   away teams. See also 'HTeam'. \"V\" (visiting) was chosen instead
+--   of \"A\" (away) simply because \"vteam\" looks better than
+--   \"ateam\". This is purely for type-safety.
+--
+newtype VTeam = VTeam { vteam :: Team } deriving (Eq, Show)
+
+
+-- | A wrapper around 'Team' that lets us distinguish between home and
+--   away teams. See also 'VTeam'. This is purely for type-safety.
+--
+newtype HTeam = HTeam { hteam :: Team } deriving (Eq, Show)
+
+
+-- * Database stuff
 
 -- Generate the Groundhog code for 'Team'.
 mkPersist defaultCodegenConfig [groundhog|
@@ -54,3 +87,20 @@ mkPersist defaultCodegenConfig [groundhog|
           type: constraint
           fields: [team_id]
 |]
+
+
+
+-- | A further refinement of 'FromXmlFk'. These types need not only a
+--   foreign key to a parent in order to make the XML -> DB
+--   conversion, but also two foreign keys to away/home teams (as
+--   represented in "TSN.Team").
+--
+class (Child a, ToDb a) => FromXmlFkTeams a where
+  -- | The function that produces a @Db a@ out of a parent foreign
+  -- key, two team foreign keys, and an @a@. The parameter order makes
+  -- it easier to map this function over a bunch of things.
+  from_xml_fk_teams :: DefaultKey (Parent a)
+                    -> DefaultKey Team -- ^ The away team FK
+                    -> DefaultKey Team -- ^ The home team FK
+                    -> a
+                    -> Db a