Database.Bolt.Extras.Template

Documentation

makeNodeLike :: Name -> Q [Dec]

Make an instance of NodeLike class. Only data types with one constructor are currently supported. Each field is transformed into Text key and its value is transformed into a Value. For example, we have a structure and define an instance:

>>> :{
data Foo = Bar
  { baz  :: Double
  , quux :: Text
  , quuz :: Maybe Int
  } deriving (Show)
makeNodeLike ''Foo
:}

Then you may create example and convert it to and from Node:

>>> let foo = Bar 42.0 "Loren ipsum" (Just 7)
>>> toNode foo
Node {nodeIdentity = -1, labels = ["Foo"], nodeProps = fromList [("baz",F 42.0),("quux",T "Loren ipsum"),("quuz",I 7)]}
>>> fromNode . toNode $ foo :: Foo
Bar {baz = 42.0, quux = "Loren ipsum", quuz = Just 7}

Maybe fields are handled correctly:

>>> let bar = Bar 42.0 "Hello world" Nothing
>>> toNode bar
Node {nodeIdentity = -1, labels = ["Foo"], nodeProps = fromList [("baz",F 42.0),("quux",T "Hello world"),("quuz",N ())]}
>>> :{
let barNode = Node
      { nodeIdentity = -1
      , labels = ["Foo"]
      , nodeProps = fromList [("baz", F 42.0), ("quux", T "Hello world")] -- No "quuz" here
      }
:}

>>> fromNode barNode :: Foo
Bar {baz = 42.0, quux = "Hello world", quuz = Nothing}

makeNodeLikeWith :: Name -> (String -> String) -> Q [Dec]

The same as makeNodeLike, but applies a function to all field names before storing them in Neo4j, like aeson does.

This can be used with fieldLabelModifier from Options in aeson:

makeNodeLikeWith ''Foo $ fieldLabelModifier $ aesonPrefix camelCase

makeURelationLike :: Name -> Q [Dec]

Make an instance of URelationLike class. Transformations are the same as in NodeLike instance declaration with the only one difference: URelationship holds only one label (or type), but Node holds list of labels.

makeURelationLikeWith :: Name -> (String -> String) -> Q [Dec]

As makeNodeLikeWith.