a48b53c · hakyll · git.iko.soy

git.iko.soy/hakyll

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Add utility getMetadataField

a48b53cJasper Van der Jeugt14 years ago

src/Hakyll/Core/Metadata.hs+22

compare with master

unifiedsplit

@@ -2,6 +2,8 @@

2module Hakyll.Core.Metadata

3 ( Metadata

4 , MonadMetadata (..)

5+ , getMetadataField

6+ , getMetadataField'

5 , makePatternDependency

7 , makePatternDependency

6 ) where

8 ) where

@@ -9,6 +11,7 @@ module Hakyll.Core.Metadata

9--------------------------------------------------------------------------------

11--------------------------------------------------------------------------------

10import Control.Monad (forM)

12import Control.Monad (forM)

11import Data.Map (Map)

13import Data.Map (Map)

14+import qualified Data.Map as M

14--------------------------------------------------------------------------------

17--------------------------------------------------------------------------------

@@ -34,6 +37,25 @@ class Monad m => MonadMetadata m where

34 return (id', metadata)

37 return (id', metadata)

40+--------------------------------------------------------------------------------

41+getMetadataField :: MonadMetadata m => Identifier -> String -> m (Maybe String)

42+getMetadataField identifier key = do

43+ metadata <- getMetadata identifier

44+ return $ M.lookup key metadata

45+

46+

47+--------------------------------------------------------------------------------

48+-- | Version of 'getMetadataField' which throws an error if the field does not

49+-- exist.

50+getMetadataField' :: MonadMetadata m => Identifier -> String -> m String

51+getMetadataField' identifier key = do

52+ field <- getMetadataField identifier key

53+ case field of

54+ Just v -> return v

55+ Nothing -> fail $ "Hakyll.Core.Metadata.getMetadataField': " ++

56+ "Item " ++ show identifier ++ " has no metadata field " ++ show key

57+

58+

37--------------------------------------------------------------------------------

59--------------------------------------------------------------------------------

38makePatternDependency :: MonadMetadata m => Pattern -> m Dependency

60makePatternDependency :: MonadMetadata m => Pattern -> m Dependency

39makePatternDependency pattern = do

61makePatternDependency pattern = do

src/Hakyll/Web/Template/Context.hs+2−2

@@ -100,8 +100,8 @@ bodyField key = field key $ return . itemBody

100-- | Map any field to its metadata value, if present

101metadataField :: Context String

102metadataField = Context $ \k i -> do

103− metadata <- getMetadata $ itemIdentifier i

103+ value <- getMetadataField (itemIdentifier i) k

104− maybe empty return $ M.lookup k metadata

104+ maybe empty return value

105

106

107--------------------------------------------------------------------------------