Support for "data" meta field

Ref #151

guide/2011505.md

@@ -2,7 +2,11 @@
 title: Zettel metadata
 ---
 
-You zettels can contain custom metadata. Neuron supports "tags" as builtin. For example:
+Every zettel must contain a "title" field in its metadata. Option metadata include "tags" and "date".
+
+## Tags
+
+You can attach one or more tags to your zettels:
 
 ```markdown
 ---
@@ -13,3 +17,18 @@ tags:
 ```
 
 Tags can also be nested using a "tag/subtag" syntax, to allow a more fine-grained organization of your Zettelkasten, especially when using advanced queries as shown in [2011506](zcf://linking-to-multiple-zettels).
+
+## Date
+
+If you are using custom ID, the creation date of the zettels can be specified in the "date" metadata field:
+
+```markdown
+---
+title: Ate steak for birthday
+date: 2020-04-07
+tags:
+  - journal
+---
+```
+
+The creation date can be made to display in a zquery result by using the `linkTheme=withDate` argument (see [2011506](zcf://linking-to-multiple-zettels)).

src/Neuron/Zettelkasten/ID.hs

@@ -8,7 +8,6 @@
 module Neuron.Zettelkasten.ID
   ( ZettelID (..),
     InvalidID (..),
-    zettelIDDay,
     zettelIDText,
     parseZettelID,
     parseZettelID',
@@ -77,12 +76,6 @@ formatDay day =
 zettelIDSourceFileName :: ZettelID -> FilePath
 zettelIDSourceFileName zid = toString $ zettelIDText zid <> ".md"
 
-zettelIDDay :: ZettelID -> Maybe Day
-zettelIDDay = \case
-  ZettelCustomID _ -> Nothing
-  ZettelDateID day _ ->
-    Just day
-
 zettelPath :: ZettelID -> Action FilePath
 zettelPath zid = do
   notesDir <- Rib.ribInputDir

src/Neuron/Zettelkasten/Query/View.hs

@@ -69,7 +69,7 @@ renderZettelLink LinkView {..} Zettel {..} = do
   let zurl = Rib.routeUrlRel $ Route_Zettel zettelID
       mextra =
         if linkViewShowDate
-          then case zettelIDDay zettelID of
+          then case zettelDay of
             Just day ->
               Just $ toHtml $ show @Text day
             Nothing ->

src/Neuron/Zettelkasten/Zettel.hs

@@ -10,6 +10,7 @@ module Neuron.Zettelkasten.Zettel where
 import Data.Aeson
 import Data.Graph.Labelled (Vertex (..))
 import Data.TagTree (Tag)
+import Data.Time.Calendar
 import Development.Shake (Action)
 import Neuron.Zettelkasten.ID
 import qualified Neuron.Zettelkasten.Zettel.Meta as Meta
@@ -22,6 +23,7 @@ data Zettel = Zettel
   { zettelID :: ZettelID,
     zettelTitle :: Text,
     zettelTags :: [Tag],
+    zettelDay :: Maybe Day,
     zettelContent :: MMark
   }
 
@@ -46,7 +48,8 @@ zettelJson :: KeyValue a => Zettel -> [a]
 zettelJson Zettel {..} =
   [ "id" .= toJSON zettelID,
     "title" .= zettelTitle,
-    "tags" .= zettelTags
+    "tags" .= zettelTags,
+    "day" .= zettelDay
   ]
 
 -- | Load a zettel from a file.
@@ -59,4 +62,9 @@ mkZettelFromPath path = do
       meta = Meta.getMeta doc
       title = maybe (toText $ "No title for " <> path) Meta.title meta
       tags = fromMaybe [] $ Meta.tags =<< meta
-  pure $ Zettel zid title tags doc
+      day = case zid of
+        -- We ignore the "data" meta field on legacy Date IDs, which encode the
+        -- creation date in the ID.
+        ZettelDateID v _ -> Just v
+        ZettelCustomID _ -> Meta.date =<< meta
+  pure $ Zettel zid title tags day doc

src/Neuron/Zettelkasten/Zettel/Meta.hs

@@ -11,13 +11,16 @@ where
 
 import Data.Aeson
 import Data.TagTree (Tag)
+import Data.Time.Calendar
 import Relude
 import Text.MMark (MMark, projectYaml)
 
 -- | YAML metadata in a zettel markdown file
 data Meta = Meta
   { title :: Text,
-    tags :: Maybe [Tag]
+    tags :: Maybe [Tag],
+    -- | Creation day
+    date :: Maybe Day
   }
   deriving (Eq, Show, Generic, FromJSON)
 

test/Neuron/Zettelkasten/ZettelSpec.hs

@@ -21,7 +21,8 @@ spec = do
   describe "sortZettelsReverseChronological" $ do
     let mkDay = fromGregorian 2020 3
         dummyContent = either error id $ parsePure "<spec>" "Dummy"
-        mkZettel day idx = Zettel (ZettelDateID (mkDay day) idx) "Some title" [Tag "science", Tag "journal/class"] dummyContent
+        mkZettel day idx =
+          Zettel (ZettelDateID (mkDay day) idx) "Some title" [Tag "science", Tag "journal/class"] Nothing dummyContent
     it "sorts correctly" $ do
       let zs = [mkZettel 3 2, mkZettel 5 1]
       sortZettelsReverseChronological zs
@@ -32,14 +33,15 @@ spec = do
         `shouldBe` [mkZettel 7 4, mkZettel 7 2]
   describe "Zettel JSON" $ do
     let day = fromGregorian 2020 3 19
-        zid = ZettelDateID day 1
+        zid = ZettelCustomID "Foo-Bar"
         dummyContent = either error id $ parsePure "<spec>" "Dummy"
-        zettel = Zettel zid "Some title" [Tag "science", Tag "journal/class"] dummyContent
+        zettel = Zettel zid "Some title" [Tag "science", Tag "journal/class"] (Just day) dummyContent
     it "Produces expected json" $ do
       -- "{\"id\":\"2011401\",\"title\":\"Some title\",\"tags\":[\"science\"]}"
       object (zettelJson zettel)
         `shouldBe` object
-          [ "id" .= ("2011401" :: Text),
+          [ "id" .= ("Foo-Bar" :: Text),
             "title" .= ("Some title" :: Text),
-            "tags" .= (["science", "journal/class"] :: [Text])
+            "tags" .= (["science", "journal/class"] :: [Text]),
+            "day" .= day
           ]