From ec4b405b09483d665e2bb6e948e2396fabb7fbeb Mon Sep 17 00:00:00 2001
From: Arnaud <156100729+arnaud-daroussin@users.noreply.github.com>
Date: Fri, 20 Dec 2024 22:21:32 +0100
Subject: [PATCH] #187 Documents state migration (#188)

* Documents state migration

* Update README.md

Co-authored-by: Arnaud <156100729+arnaud-daroussin@users.noreply.github.com>

* Validates snippets with mdoc

* Improves readiness

---------

Co-authored-by: novakov-alexey <117519424+novakov-alexey@users.noreply.github.com>
---
 README.md | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/README.md b/README.md
index 961037d..21a9675 100644
--- a/README.md
+++ b/README.md
@@ -13,6 +13,8 @@ This project is a community-maintained fork of official Apache Flink Scala API,
 `flink-scala-api` uses a different package name for all api-related classes like `DataStream`, so you can do
 gradual migration of a big project and use both upstream and this versions of scala API in the same project. 
 
+### API
+
 The actual migration should be straightforward and simple, replace old import to the new ones:
 ```scala
 // original api import
@@ -24,6 +26,27 @@ import org.apache.flinkx.api._
 import org.apache.flinkx.api.serializers._
 ```
 
+### State
+
+Ensure to replace state descriptor constructors using `Class[T]` param with constructors using `TypeInformation[T]` or `TypeSerializer[T]` param:
+```scala mdoc
+import org.apache.flink.api.common.state.ValueStateDescriptor
+import org.apache.flink.api.common.typeinfo.TypeInformation
+
+// state using Kryo
+val eventStateDescriptor = new ValueStateDescriptor[Option[String]]("event",
+  classOf[Option[String]])
+```
+```scala mdoc:reset-object
+import org.apache.flinkx.api.serializers._
+import org.apache.flink.api.common.state.ValueStateDescriptor
+import org.apache.flink.api.common.typeinfo.TypeInformation
+
+// state using flink-scala-api
+val eventStateDescriptor = new ValueStateDescriptor[Option[String]]("event",
+  implicitly[TypeInformation[Option[String]]])
+```
+
 ## Usage 
 
 `flink-scala-api` is released to Maven-central for 2.13 and 3. For SBT, add this snippet to `build.sbt`: