snaplet-bloodhound

A boilerplate snaplet to conveniently allow bloodhound ElasticSearch functions to be lifted into snap web handlers.

Usage

1. Add the BloodhoundEnv to your apps core state:

  import Snap.Snaplet.Bloodhound
  data App = App
    {...
    ,_bloodhoundEnv :: Snaplet BloodhoundEnv
    ,...
    }

2. Derive (or manually create) lenses:

makeLenses ''App

3. Implement a HasBHEnv instance:

  instance HasBHEnv App where
    bhEnv = bloodhoundEnv . bhEnv

4. In your initialisation function, initialise like so, providing a value for server in the devel.cfg file found under the corresponding snaplet directory snaplets/bloodhound/devel.cfg.

  app :: SnapletInit App App
  app = makeSnaplet "app" "Your application" Nothing $ do
    ...
    bloodhoundSnaplet <- nestSnaplet "bloodhound" bloodhoundEnv bloodhoundEnvInit
    ...
    return $ App ... bloodhoundSnaplet ...

5. You should find Handler b App now has a MonadBH instance, and so bloodhound functions that require one can be called in your handler. E.G:

  -- Some bloodhound search function
  searchYourDocuments :: MonadBH m => Search -> m Reply
  searchYourDocuments = searchByType yourIndexName yourMappingName

  -- Can now be used inside your handlers.
  doSomethingWithYourDocs :: Handler App App ()
  doSomethingWithYourDocs = do
    eDoc :: Either EsError (SearchResult YourDocument) <- parseEsResponse =<< searchYourDocuments
    case eDoc of
      Left err
        -> fail . show $ err

      Right (SearchResult _took _timedout _shards (SearchHits _hTotal _hMaxScore hits) _hAggs _hmScrollId)
        -> map (\(Hit _hIndex _hType _hDocId _hScore hSource _hHighlight) -> case hSource of
                   Nothing                 -> ...
                   Just (YourDocument ...) -> ...
               )
               hits