diff --git a/ebook-manager.cabal b/ebook-manager.cabal
index b574f6a..2d699d6 100644
--- a/ebook-manager.cabal
+++ b/ebook-manager.cabal
@@ -28,6 +28,7 @@ executable ebook-manager
                      , Database
                      , Database.Book
                      , Database.Channel
+                     , Database.Tag
                      , Database.Schema
                      , Database.User
                      , Datastore
diff --git a/src/API/Books.hs b/src/API/Books.hs
index acbca89..1448b08 100644
--- a/src/API/Books.hs
+++ b/src/API/Books.hs
@@ -21,9 +21,9 @@ import ClassyPrelude
 import Server.Auth
 import Servant.Auth as SA
 import Data.Aeson
-import API.Channels (JsonChannel(..))
 import Database.Book
 import Database.Channel
+import Database.Tag
 import Database
 import Control.Lens
 import Data.Generics.Product
@@ -38,13 +38,15 @@ data JsonBook = JsonBook { identifier :: BookID
                          , contentType :: Text
                          , title :: Maybe Text
                          , description :: Maybe Text
-                         , channels :: [JsonChannel] }
+                         , channels :: [Text]
+                         , tags :: [Text] }
               deriving (Generic, Show)
 
 data PostBook = PostBook { contentType :: Text
                          , title :: Maybe Text
                          , description :: Maybe Text
-                         , channels :: [JsonChannel] }
+                         , channels :: [Text]
+                         , tags :: [Text] }
               deriving (Generic, Show)
 
 
@@ -105,5 +107,6 @@ listBooksHandler = requireLoggedIn $ \user -> do
   runDB (usersBooks (view (field @"username") user) >>= mapM augment)
     where
       augment Book{identifier=bookId,contentType,title,description} = do
-        channels <- fmap (\Channel{..} -> JsonChannel{..}) <$> booksChannels bookId
+        channels <- fmap (view (field @"channel")) <$> booksChannels bookId
+        tags <- fmap (view (field @"tag")) <$> booksTags bookId
         pure JsonBook{identifier=bookId,..}
diff --git a/src/Database.hs b/src/Database.hs
index cb0d686..ebeb307 100644
--- a/src/Database.hs
+++ b/src/Database.hs
@@ -11,6 +11,7 @@ module Database
   , fromRel
   , fromRels
   , toRel
+  , transaction
   , SeldaT )
   where
 
@@ -18,7 +19,7 @@ import Data.Generics.Product
 import Control.Lens (view)
 import Data.Pool (Pool, withResource)
 import Database.Selda.Backend (SeldaConnection, runSeldaT, SeldaT)
-import Database.Selda (query, select)
+import Database.Selda (query, select, transaction)
 import Database.Selda.Generic (gen, fromRel, fromRels, toRel)
 import ClassyPrelude
 
diff --git a/src/Database/Book.hs b/src/Database/Book.hs
index 876290b..37400a1 100644
--- a/src/Database/Book.hs
+++ b/src/Database/Book.hs
@@ -18,11 +18,13 @@ module Database.Book
   , BookID) where
 
 import ClassyPrelude
-import Database.Schema
+import Database.Schema (books, users, Username, Book(..), BookID(..), UserID, HashDigest(..))
 import Database
 import Database.Selda
 import Database.Selda.Generic
 
+import Database.Tag (attachTag)
+
 usersBooks :: (MonadSelda m, MonadMask m, MonadIO m) => Username -> m [Book]
 usersBooks username = fromRels <$> query q
   where
@@ -64,7 +66,8 @@ data UpdateBook = UpdateBook { identifier :: BookID
                              , contentType :: Text
                              , title :: Maybe Text
                              , description :: Maybe Text
-                             , owner :: Username }
+                             , owner :: Username
+                             , tags :: [Text]}
 
 bookExists :: (MonadSelda m, MonadMask m, MonadIO m) => BookID -> m Bool
 bookExists identifier = not . null <$> query q
@@ -88,13 +91,19 @@ bookOwner' identifier username = do
 
 updateBook :: (MonadSelda m, MonadMask m, MonadIO m) => UpdateBook -> m (Maybe UpdateBook)
 updateBook book@UpdateBook{..} = do
-  mUserId <- query (bookOwner' identifier owner)
-  forM (listToMaybe mUserId) $ \_userId -> do
-    update_ (gen books) predicate (\b -> b `with` [ pContentType := literal contentType
-                                                  , pTitle := literal title
-                                                  , pDescription := literal description ])
-    return book
+  connectChannels
+  connectTags
+  updateBook'
   where
+    connectTags = mapM_ (attachTag owner identifier) tags
+    connectChannels = return ()
+    updateBook' = do
+      mUserId <- query (bookOwner' identifier owner)
+      forM (listToMaybe mUserId) $ \_userId -> do
+        update_ (gen books) predicate (\b -> b `with` [ pContentType := literal contentType
+                                                      , pTitle := literal title
+                                                      , pDescription := literal description ])
+        return book
     _ :*: _ :*: pContentType :*: pTitle :*: pDescription :*: _ = selectors (gen books)
     predicate (bookId :*: _) = bookId .== literal identifier
 
diff --git a/src/Database/Channel.hs b/src/Database/Channel.hs
index 3b85fe2..7da845f 100644
--- a/src/Database/Channel.hs
+++ b/src/Database/Channel.hs
@@ -36,11 +36,11 @@ insertChannel username channel = do
       return userId
 
 booksChannels :: (MonadMask m, MonadIO m) => BookID -> SeldaT m [Channel]
-booksChannels contentHash = fromRels <$> query q
+booksChannels bookId = fromRels <$> query q
   where
     q = do
-      channelId :*: contentHash' <- select (gen bookChannels)
+      channelId :*: bookId' <- select (gen bookChannels)
       ch@(channelId' :*: _) <- select (gen channels)
       restrict (channelId .== channelId')
-      restrict (contentHash' .== literal contentHash)
+      restrict (bookId' .== literal bookId)
       return ch
diff --git a/src/Database/Tag.hs b/src/Database/Tag.hs
new file mode 100644
index 0000000..ff6426a
--- /dev/null
+++ b/src/Database/Tag.hs
@@ -0,0 +1,57 @@
+{-# Language TypeApplications #-}
+{-# Language TypeOperators #-}
+{-# Language DataKinds #-}
+{-# Language DuplicateRecordFields #-}
+{-# Language NamedFieldPuns #-}
+module Database.Tag
+  ( def
+  , booksTags
+  , attachTag
+  , upsertTag
+  , Tag(..) ) where
+
+import ClassyPrelude
+import Database.Schema
+import Database
+import Database.Selda
+import Database.Selda.Generic
+
+upsertTag :: (MonadMask m, MonadIO m, MonadSelda m) => Username -> Text -> m Tag
+upsertTag username tag = do
+  -- I want this to error out if some data is invariant is wrong and roll back
+  -- the transaction. Also as a side note, run this in a transaction plz
+  [userId] <- query userQ
+  void $ upsert (gen tags) (predicate userId) id [toRel (Tag def tag userId)]
+  [t] <- fromRels <$> query (tagQ userId)
+  return t
+  where
+    predicate userId (_ :*: tag' :*: owner) = tag' .== literal tag .&& owner .== literal userId
+    tagQ userId = do
+      t@(_ :*: tag' :*: owner) <- select (gen tags)
+      restrict (tag' .== literal tag .&& owner .== literal userId)
+      return t
+    userQ = do
+      userId :*: _ :*: username' :*: _ <- select (gen users)
+      restrict (username' .== literal username)
+      return userId
+
+booksTags :: (MonadMask m, MonadIO m, MonadSelda m) => BookID -> m [Tag]
+booksTags bookId = fromRels <$> query q
+  where
+    q = do
+      tagId :*: bookId' <- select (gen bookTags)
+      tag@(tagId' :*: _) <- select (gen tags)
+      restrict (tagId .== tagId')
+      restrict (bookId' .== literal bookId)
+      return tag
+
+attachTag :: (MonadMask m, MonadIO m, MonadSelda m) => Username -> BookID -> Text -> m ()
+attachTag username bookId tag = do
+  Tag{identifier} <- upsertTag username tag
+  whenM (null <$> query (tagQ identifier)) $
+    void $ insertGen bookTags [BookTag identifier bookId]
+  where
+    tagQ tagId = do
+      (tagId' :*: bookId') <- select (gen bookTags)
+      restrict (tagId' .== literal tagId .&& bookId' .== literal bookId)
+      return tagId'