From c57552489fd715ad51c118fed998bd6eb59a9be8 Mon Sep 17 00:00:00 2001
From: Joe Hansche <jhansche@themeetgroup.com>
Date: Thu, 24 Aug 2017 11:27:53 -0700
Subject: [PATCH] Properly decode JSONObject.NULL => null [Fixes #209]

ParseEncoder encodes (null) => JSONObject.NULL. But ParseDecoder was not
doing the inverse conversion.

That resulted in JSONObject.NULL values being in the ParseObject.State map,
which means any calls to State.get(key) that were casting the result to a
specific type (i.e., String) without first checking the Object return type
would result in a ClassCastException.

ParseObject already accounts for this possibility by checking the Object type
before casting it, and returning null if the type did not match.

The known case that causes crashes is #209, where ParseUser.State.sessionToken()
casts the result of get(KEY_SESSION_TOKEN) to String. When that was null it
would be encoded as JSONObject.NULL due to the ParseEncoder; but after decoding
it would not convert back to a native null, leading to the ClassCastException.
---
 Parse/src/main/java/com/parse/ParseDecoder.java     | 4 ++++
 Parse/src/test/java/com/parse/ParseDecoderTest.java | 6 ++++++
 2 files changed, 10 insertions(+)

diff --git a/Parse/src/main/java/com/parse/ParseDecoder.java b/Parse/src/main/java/com/parse/ParseDecoder.java
index 9493e3c1b..a8f961f57 100644
--- a/Parse/src/main/java/com/parse/ParseDecoder.java
+++ b/Parse/src/main/java/com/parse/ParseDecoder.java
@@ -71,6 +71,10 @@ public Object decode(Object object) {
       return convertJSONArrayToList((JSONArray) object);
     }
 
+    if (object == JSONObject.NULL) {
+      return null;
+    }
+
     if (!(object instanceof JSONObject)) {
       return object;
     }
diff --git a/Parse/src/test/java/com/parse/ParseDecoderTest.java b/Parse/src/test/java/com/parse/ParseDecoderTest.java
index 6a24d0880..5efb5de74 100644
--- a/Parse/src/test/java/com/parse/ParseDecoderTest.java
+++ b/Parse/src/test/java/com/parse/ParseDecoderTest.java
@@ -73,6 +73,12 @@ public void testNonJSONObject() {
     assertSame(obj, ParseDecoder.get().decode(obj));
   }
 
+  @Test
+  public void testNull() {
+    Object object = ParseDecoder.get().decode(JSONObject.NULL);
+    assertNull(object);
+  }
+
   @Test
   public void testParseFieldOperations() throws JSONException {
     JSONObject json = new JSONObject();