diff options
| -rw-r--r-- | src/Hakyll/Core/Metadata.hs | 22 | ||||
| -rw-r--r-- | src/Hakyll/Web/Template/Context.hs | 4 |
2 files changed, 24 insertions, 2 deletions
diff --git a/src/Hakyll/Core/Metadata.hs b/src/Hakyll/Core/Metadata.hs index 9fc2d3e..7902b94 100644 --- a/src/Hakyll/Core/Metadata.hs +++ b/src/Hakyll/Core/Metadata.hs @@ -2,6 +2,8 @@ module Hakyll.Core.Metadata ( Metadata , MonadMetadata (..) + , getMetadataField + , getMetadataField' , makePatternDependency ) where @@ -9,6 +11,7 @@ module Hakyll.Core.Metadata -------------------------------------------------------------------------------- import Control.Monad (forM) import Data.Map (Map) +import qualified Data.Map as M -------------------------------------------------------------------------------- @@ -35,6 +38,25 @@ class Monad m => MonadMetadata m where -------------------------------------------------------------------------------- +getMetadataField :: MonadMetadata m => Identifier -> String -> m (Maybe String) +getMetadataField identifier key = do + metadata <- getMetadata identifier + return $ M.lookup key metadata + + +-------------------------------------------------------------------------------- +-- | Version of 'getMetadataField' which throws an error if the field does not +-- exist. +getMetadataField' :: MonadMetadata m => Identifier -> String -> m String +getMetadataField' identifier key = do + field <- getMetadataField identifier key + case field of + Just v -> return v + Nothing -> fail $ "Hakyll.Core.Metadata.getMetadataField': " ++ + "Item " ++ show identifier ++ " has no metadata field " ++ show key + + +-------------------------------------------------------------------------------- makePatternDependency :: MonadMetadata m => Pattern -> m Dependency makePatternDependency pattern = do matches' <- getMatches pattern diff --git a/src/Hakyll/Web/Template/Context.hs b/src/Hakyll/Web/Template/Context.hs index 1a9aba3..f9c96d0 100644 --- a/src/Hakyll/Web/Template/Context.hs +++ b/src/Hakyll/Web/Template/Context.hs @@ -100,8 +100,8 @@ bodyField key = field key $ return . itemBody -- | Map any field to its metadata value, if present metadataField :: Context String metadataField = Context $ \k i -> do - metadata <- getMetadata $ itemIdentifier i - maybe empty return $ M.lookup k metadata + value <- getMetadataField (itemIdentifier i) k + maybe empty return value -------------------------------------------------------------------------------- |