Fix FasterXML#2749

sp4ce · Jun 8, 2020 · 2a6a960 · 2a6a960
1 parent 00d7356
commit 2a6a960
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Showing 3 changed files with 13 additions and 4 deletions.
diff --git a/src/main/java/com/fasterxml/jackson/databind/DeserializationContext.java b/src/main/java/com/fasterxml/jackson/databind/DeserializationContext.java
@@ -205,8 +205,11 @@ protected DeserializationContext(DeserializationContext src,
     {
         _cache = src._cache;
         _factory = src._factory;
-        _readCapabilities = p.getReadCapabilities();
-
+        // 08-Jun-2020. tatu: Called only for `ObjectMapper.canDeserialize()`
+        //    (see [databind#2749]), not sure what's the best work-around but
+        //    start with this:
+        _readCapabilities = (p == null) ? null : p.getReadCapabilities();
+
         _config = config;
         _featureFlags = config.getDeserializationFeatures();
         _view = config.getActiveView();

diff --git a/src/main/java/com/fasterxml/jackson/databind/ObjectMapper.java b/src/main/java/com/fasterxml/jackson/databind/ObjectMapper.java
@@ -3324,7 +3324,7 @@ public boolean canDeserialize(JavaType type, AtomicReference<Throwable> cause)
         return createDeserializationContext(null,
                 getDeserializationConfig()).hasValueDeserializerFor(type, cause);
     }
-    
+
     /*
     /**********************************************************
     /* Extended Public API, deserialization,

diff --git a/src/test/java/com/fasterxml/jackson/databind/ObjectMapperTest.java b/src/test/java/com/fasterxml/jackson/databind/ObjectMapperTest.java
@@ -251,7 +251,6 @@ public void testConfigForPropertySorting() throws Exception
         assertTrue(dc.shouldSortPropertiesAlphabetically());
     }
 
-
     public void testJsonFactoryLinkage()
     {
         // first, implicit factory, giving implicit linkage
@@ -342,6 +341,13 @@ public void testEmptyBeanSerializability()
                 .canSerialize(EmptyBean.class));
     }
 
+    // for [databind#2749]: just to check there's no NPE; method really not useful
+    public void testCanDeserialize()
+    {
+        assertTrue(MAPPER.canDeserialize(MAPPER.constructType(EmptyBean.class)));
+        assertTrue(MAPPER.canDeserialize(MAPPER.constructType(Object.class)));
+    }
+
     // for [databind#898]
     public void testSerializerProviderAccess() throws Exception
     {