haskell - Return JSON based on Persistent Query from yesod handler -

this additional question @konstantinerybnikov return json yesod handler.

what if want have persistent query selectlist , result data must return json format? code it?

here code (adopt code of @konstantinerybnikov):

    -- json     import           data.aeson      (object, (.=))     import qualified data.aeson      j     import           yesod.core.json (returnjson)      getimagesr :: handler value     getimagesr =           images <- rundb $ selectlist [imagesfilename !=. ""] [desc imagesdate]           return $ object (if null images [] else [] -- want result of perstent in json format) 

``

hope me thank you.

i guess main problem selectlist returns list of entity record (where record type querying) instead of record, we'll have list of records using map entityval (entityval defined in entity). handler :

getimagesr =   images <- rundb $ selectlist [imagesfilename !=. ""] [desc imagesdate]   returnjson (map entityval images) 

now it's matter of transforming [record] json. luckily, can done automatically adding word json persistent model definition (as shown here).