Try out the book schema

src/Database/Schema.hs

@@ -9,7 +9,9 @@ import Database.Selda.Generic
 import Database.Selda
 import Database.Selda.Backend
 
-data User pass = User { email :: Text
+-- | User type
+data User pass = User { identifier :: RowID
+                      , email :: Text
                       , username :: Text
                       , role :: Role
                       , password :: pass }
@@ -26,4 +28,79 @@ instance SqlType Role where
   defaultValue = mkLit minBound
 
 users :: GenTable (User ByteString)
-users = genTable "users" [ email :- primaryGen ]
+users = genTable "users" [ (email :: User ByteString -> Text) :- uniqueGen
+                         , username :- uniqueGen
+                         , (identifier :: User ByteString -> RowID) :- autoPrimaryGen ]
+
+-- | Book type
+newtype HashDigest = HashDigest { unHex :: Text } deriving Show
+data Book = Book { contentHash :: HashDigest
+                 , contentType :: Text
+                 , title :: Maybe Text
+                 , description :: Maybe Text }
+          deriving (Show, Generic)
+
+instance SqlType HashDigest where
+  mkLit = LCustom . LText . unHex
+  fromSql (SqlString x) = HashDigest x
+  fromSql _ = error "fromSql: Not a valid hash digest"
+  defaultValue = mkLit (HashDigest "") -- Doesn't really make sense
+
+books :: GenTable Book
+books = genTable "books" [ contentHash :- primaryGen ]
+
+data UserBook = UserBook { email :: Text
+                         , book :: HashDigest }
+              deriving (Generic, Show)
+
+userBooks :: GenTable UserBook
+userBooks = genTable "user_book" [ (email :: UserBook -> Text) :- fkGen (gen users) userEmail
+                                 , (book :: UserBook -> HashDigest) :- fkGen (gen books) bookHash ]
+  where
+    _ :*: userEmail :*: _ = selectors (gen users)
+    bookHash :*: _ = selectors (gen books)
+
+-- | Categorizing books
+data Tag = Tag { identifier :: RowID
+               , tag :: Text
+               , owner :: RowID }
+         deriving (Show, Generic)
+
+data Channel = Channel { identifier :: RowID
+                       , channel :: Text
+                       , owner :: RowID }
+             deriving (Show, Generic)
+
+tags :: GenTable Tag
+tags = genTable "tags" [ (identifier :: Tag -> RowID) :- autoPrimaryGen
+                       , (owner :: Tag -> RowID) :- fkGen (gen users) i ]
+  where
+    i :*: _ = selectors (gen users)
+
+channels :: GenTable Channel
+channels = genTable "tags" [ (identifier :: Channel -> RowID) :- autoPrimaryGen
+                           , (owner :: Channel -> RowID) :- fkGen (gen users) i ]
+  where
+    i :*: _ = selectors (gen users)
+
+data BookTag = BookTag { tag :: RowID
+                       , book :: HashDigest }
+             deriving (Show, Generic)
+
+data BookChannel = BookChannel { channel :: RowID
+                               , book :: HashDigest }
+                 deriving (Show, Generic)
+
+bookTags :: GenTable BookTag
+bookTags = genTable "book_tags" [ (tag :: BookTag -> RowID) :- fkGen (gen tags) i
+                                , (book :: BookTag -> HashDigest) :- fkGen (gen books) h ]
+  where
+    i :*: _ = selectors (gen tags)
+    h :*: _ = selectors (gen books)
+
+bookChannels :: GenTable BookChannel
+bookChannels = genTable "book_channels" [ (channel :: BookChannel -> RowID) :- fkGen (gen channels) i
+                                        , (book :: BookChannel -> HashDigest) :- fkGen (gen books) h ]
+  where
+    i :*: _ = selectors (gen channels)
+    h :*: _ = selectors (gen books)