Fix #33

Author: cowtowncoder

afterburner/src/main/java/com/fasterxml/jackson/module/afterburner/ser/StringFieldPropertyWriter.java

@@ -48,7 +48,10 @@ public final void serializeAsField(Object bean, JsonGenerator gen, SerializerPro
         }
         // Null (etc) handling; copied from super-class impl
         if (value == null) {
-            if (!_suppressNulls) {
+            if (_nullSerializer != null) {
+                gen.writeFieldName(_fastName);
+                _nullSerializer.serialize(null, gen, prov);
+            } else if (!_suppressNulls) {
                 gen.writeFieldName(_fastName);
                 prov.defaultSerializeNull(gen);
             }

afterburner/src/main/java/com/fasterxml/jackson/module/afterburner/ser/StringMethodPropertyWriter.java

@@ -48,7 +48,10 @@ public final void serializeAsField(Object bean, JsonGenerator gen, SerializerPro
         }
         // Null (etc) handling; copied from super-class impl
         if (value == null) {
-            if (!_suppressNulls) {
+            if (_nullSerializer != null) {
+                gen.writeFieldName(_fastName);
+                _nullSerializer.serialize(null, gen, prov);
+            } else if (!_suppressNulls) {
                 gen.writeFieldName(_fastName);
                 prov.defaultSerializeNull(gen);
             }

afterburner/src/test/java/com/fasterxml/jackson/module/afterburner/ser/NullSerializationTest.java

@@ -0,0 +1,121 @@
+package com.fasterxml.jackson.module.afterburner.ser;
+
+import java.io.*;
+
+import com.fasterxml.jackson.core.*;
+
+import com.fasterxml.jackson.databind.*;
+import com.fasterxml.jackson.databind.annotation.JsonSerialize;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.fasterxml.jackson.databind.ser.DefaultSerializerProvider;
+import com.fasterxml.jackson.databind.ser.SerializerFactory;
+import com.fasterxml.jackson.module.afterburner.AfterburnerTestBase;
+
+// Copied from [com.fasterxml.jackson.databind.ser.filter]
+public class NullSerializationTest extends AfterburnerTestBase
+{
+    static class NullSerializer extends JsonSerializer<Object>
+    {
+        @Override
+        public void serialize(Object value, JsonGenerator gen, SerializerProvider provider)
+            throws IOException
+        {
+            gen.writeString("foobar");
+        }
+    }
+
+    static class Bean1 {
+        public String name = null;
+    }
+
+    static class Bean2 {
+        public String type = null;
+    }
+
+    @SuppressWarnings("serial")
+    static class MyNullProvider extends DefaultSerializerProvider
+    {
+        public MyNullProvider() { super(); }
+        public MyNullProvider(MyNullProvider base, SerializationConfig config, SerializerFactory jsf) {
+            super(base, config, jsf);
+        }
+
+        // not really a proper impl, but has to do
+        @Override
+        public DefaultSerializerProvider copy() {
+            return this;
+        }
+        
+        @Override
+        public DefaultSerializerProvider createInstance(SerializationConfig config, SerializerFactory jsf) {
+            return new MyNullProvider(this, config, jsf);
+        }
+
+        @Override
+        public JsonSerializer<Object> findNullValueSerializer(BeanProperty property)
+            throws JsonMappingException
+        {
+            if ("name".equals(property.getName())) {
+                return new NullSerializer();
+            }
+            return super.findNullValueSerializer(property);
+        }
+    }
+
+    static class BeanWithNullProps
+    {
+        @JsonSerialize(nullsUsing=NullSerializer.class)
+        public String a = null;
+    }
+
+    /*
+    /**********************************************************
+    /* Test methods
+    /**********************************************************
+     */
+
+    private final ObjectMapper MAPPER = mapperWithModule();
+    
+    public void testSimple() throws Exception
+    {
+        assertEquals("null", MAPPER.writeValueAsString(null));
+    }
+
+    public void testOverriddenDefaultNulls() throws Exception
+    {
+        DefaultSerializerProvider sp = new DefaultSerializerProvider.Impl();
+        sp.setNullValueSerializer(new NullSerializer());
+        ObjectMapper m = new ObjectMapper();
+        m.setSerializerProvider(sp);
+        assertEquals("\"foobar\"", m.writeValueAsString(null));
+    }
+
+    public void testCustomPOJONullsViaProvider() throws Exception
+    {
+        ObjectMapper m = new ObjectMapper();
+        m.setSerializerProvider(new MyNullProvider());
+        assertEquals("{\"name\":\"foobar\"}", m.writeValueAsString(new Bean1()));
+        assertEquals("{\"type\":null}", m.writeValueAsString(new Bean2()));
+    }
+
+    public void testCustomTreeNullsViaProvider() throws Exception
+    {
+        ObjectNode root = MAPPER.createObjectNode();
+        root.putNull("a");
+
+        // by default, null is... well, null
+        assertEquals("{\"a\":null}", MAPPER.writeValueAsString(root));
+
+        // but then we can customize it:
+        DefaultSerializerProvider prov = new MyNullProvider();
+        prov.setNullValueSerializer(new NullSerializer());
+        ObjectMapper m = new ObjectMapper();
+        m.setSerializerProvider(prov);
+        assertEquals("{\"a\":\"foobar\"}", m.writeValueAsString(root));
+    }
+
+    public void testNullSerializeViaPropertyAnnotation() throws Exception
+    {
+        assertEquals("{\"a\":\"foobar\"}", MAPPER.writeValueAsString(new BeanWithNullProps()));
+    }
+}

release-notes/VERSION

@@ -15,6 +15,7 @@ Modules:
 #30: (afterburner) `IncompatibleClassChangeError` deserializing interface
   methods with default impl
  (reported by Shawn S)
+#33: (afterburner) `@JsonSerialize` with `nullUsing` option not working for `String` properties
 
 2.8.10 (24-Aug-2017)
 2.8.9 (12-Jun-2017)