src/TSN/Team.hs

   1 {-# LANGUAGE FlexibleInstances #-}
   2 {-# LANGUAGE GADTs #-}
   3 {-# LANGUAGE QuasiQuotes #-}
   4 {-# LANGUAGE TemplateHaskell #-}
   5 {-# LANGUAGE TypeFamilies #-}
   6
   7 -- | (At least) two different XML types have a notion of teams:
   8 --   "TSN.XML.Odds" and "TSN.XML.JFile". And in fact those two types
   9 --   agree on the team id, abbreviation, and name -- at least for the
  10 --   database representation.
  11 --
  12 --   This module contains a data type for the common database
  13 --   representation.
  14 --
  15 module TSN.Team (
  16   HTeam(..),
  17   FromXmlFkTeams(..),
  18   Team(..),
  19   VTeam(..),
  20   -- * WARNING: these are private but exported to silence warnings
  21   TeamConstructor(..) )
  22 where
  23
  24 -- System imports
  25 import Database.Groundhog () -- Required for some String instance
  26 import Database.Groundhog.Core ( PersistEntity(..) )
  27 import Database.Groundhog.TH (
  28   defaultCodegenConfig,
  29   groundhog,
  30   mkPersist )
  31
  32 -- Local imports
  33 import Xml ( Child(..), Db(..) )
  34
  35
  36 -- * Team
  37
  38 -- | The database representation of a team. The 'team_id' is a
  39 --   'String' field because some teams do in fact have ids like
  40 --   \"B52\". The pointless \"team_\" prefix is left on the 'team_id'
  41 --   field because otherwise the auto-generated column name would
  42 --   conflict with the default \"id\" primary key.
  43 --
  44 data Team =
  45   Team {
  46     team_id :: String, -- ^ Some of them contain characters
  47     abbreviation :: Maybe String, -- ^ Some teams don't have abbreviations,
  48                                   --   or at least, some sample jfilexml
  49                                   --   don't have them for some teams.
  50     name :: Maybe String -- ^ Some teams don't even have names!
  51     }
  52   deriving (Eq, Show)
  53
  54
  55 -- * VTeam / HTeam
  56
  57 -- | A wrapper around 'Team' that lets us distinguish between home and
  58 --   away teams. See also 'HTeam'. \"V\" (visiting) was chosen instead
  59 --   of \"A\" (away) simply because \"vteam\" looks better than
  60 --   \"ateam\". This is purely for type-safety.
  61 --
  62 newtype VTeam = VTeam { vteam :: Team } deriving (Eq, Show)
  63
  64
  65 -- | A wrapper around 'Team' that lets us distinguish between home and
  66 --   away teams. See also 'VTeam'. This is purely for type-safety.
  67 --
  68 newtype HTeam = HTeam { hteam :: Team } deriving (Eq, Show)
  69
  70
  71 -- * Database stuff
  72
  73 -- Generate the Groundhog code for 'Team'.
  74 mkPersist defaultCodegenConfig [groundhog|
  75 - entity: Team
  76   dbName: teams
  77   constructors:
  78     - name: Team
  79       uniques:
  80         - name: unique_team
  81           type: constraint
  82           fields: [team_id]
  83 |]
  84
  85
  86
  87 -- | A further refinement of 'FromXmlFk'. These types need not only a
  88 --   foreign key to a parent in order to make the XML -> DB
  89 --   conversion, but also two foreign keys to away/home teams (as
  90 --   represented in "TSN.Team").
  91 --
  92 class (Child a, ToDb a) => FromXmlFkTeams a where
  93   -- | The function that produces a @Db a@ out of a parent foreign
  94   -- key, two team foreign keys, and an @a@. The parameter order makes
  95   -- it easier to map this function over a bunch of things.
  96   from_xml_fk_teams :: DefaultKey (Parent a)
  97                     -> DefaultKey Team -- ^ The away team FK
  98                     -> DefaultKey Team -- ^ The home team FK
  99                     -> a
 100                     -> Db a