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diff --git a/README.markdown b/README.markdown index 3550dd1..d8c3986 100644 --- a/README.markdown +++ b/README.markdown @@ -172,6 +172,20 @@ This is a bit more verbose in its definition and the resulting JSON but transpor Note that this is the approach _spray-json_ uses for case classes. +### JsonFormats for recursive Types + +If your type is recursive such as + + case class Foo(i: Int, foo: Foo) + +you need to wrap your format constructor with `lazyFormat` and supply an explicit type annotation: + + implicit val fooFormat: JsonFormat[Foo] = lazyFormat(jsonFormat(Foo, "i", "foo")) + +Otherwise your code will either not compile (no explicit type annotation) or throw an NPE at runtime (no `lazyFormat` +wrapper). + + ### API Documentation You can find the documentation for the _spray-json_ API here: |