Implement #38

release-notes/VERSION

@@ -1,6 +1,7 @@
 Project: jackson-dataformat-xml
 Version: 2.3.0 (xx-xxx-2013)
 
+#38: Support root-level Collection serialization
 - Add support for `JsonGenerator.Feature.WRITE_BIGDECIMAL_AS_PLAIN`
 - Improved indentation
 

src/main/java/com/fasterxml/jackson/dataformat/xml/ser/ToXmlGenerator.java

@@ -324,6 +324,18 @@ public void finishWrappedValue(QName wrapperName, QName wrappedName) throws IOEx
         }
     }
 
+    /**
+     * Trivial helper method called when to add a replicated wrapper name
+     * 
+     * @since 2.2
+     */
+    public void writeRepeatedFieldName() throws IOException, JsonGenerationException
+    {
+        if (_writeContext.writeFieldName(_nextName.getLocalPart()) == JsonWriteContext.STATUS_EXPECT_VALUE) {
+            _reportError("Can not write a field name, expecting a value");
+        }
+    }
+
     /*
     /**********************************************************
     /* JsonGenerator method overrides

src/main/java/com/fasterxml/jackson/dataformat/xml/ser/XmlBeanSerializer.java

@@ -121,15 +121,14 @@ public BeanSerializer withObjectIdWriter(ObjectIdWriter objectIdWriter) {
      * extra handling, such as indication of whether to write attributes or
      * elements.
      */
-    @SuppressWarnings("deprecation")
     @Override
     protected void serializeFields(Object bean, JsonGenerator jgen0, SerializerProvider provider)
         throws IOException, JsonGenerationException
     {
         final ToXmlGenerator xgen = (ToXmlGenerator) jgen0;
         final BeanPropertyWriter[] props;
         // !!! TODO: change to use non-deprecated version in 2.3
-        if (_filteredProps != null && provider.getSerializationView() != null) {
+        if (_filteredProps != null && provider.getActiveView() != null) {
             props = _filteredProps;
         } else {
             props = _props;

src/main/java/com/fasterxml/jackson/dataformat/xml/ser/XmlSerializerProvider.java

@@ -1,16 +1,20 @@
 package com.fasterxml.jackson.dataformat.xml.ser;
 
 import java.io.IOException;
+import java.util.Collection;
+
 import javax.xml.namespace.QName;
 import javax.xml.stream.XMLStreamException;
 
 import com.fasterxml.jackson.core.*;
 import com.fasterxml.jackson.databind.JavaType;
+import com.fasterxml.jackson.databind.JsonMappingException;
 import com.fasterxml.jackson.databind.JsonSerializer;
 import com.fasterxml.jackson.databind.SerializationConfig;
 import com.fasterxml.jackson.databind.ser.SerializerFactory;
 import com.fasterxml.jackson.databind.ser.DefaultSerializerProvider;
 import com.fasterxml.jackson.dataformat.xml.util.StaxUtil;
+import com.fasterxml.jackson.dataformat.xml.util.TypeUtil;
 import com.fasterxml.jackson.dataformat.xml.util.XmlRootNameLookup;
 
 
@@ -56,37 +60,141 @@ public DefaultSerializerProvider createInstance(SerializationConfig config,
     {
         return new XmlSerializerProvider(this, config, jsf);
     }
-    
+
     @Override
     public void serializeValue(JsonGenerator jgen, Object value)
         throws IOException, JsonProcessingException
     {
-        QName rootName = (value == null) ? ROOT_NAME_FOR_NULL
-                : _rootNameLookup.findRootName(value.getClass(), _config);
+        if (value == null) {
+            _serializeNull(jgen);
+            return;
+        }
+        Class<?> cls = value.getClass();
+        QName rootName = _rootNameFromConfig();
+        if (rootName == null) {
+            rootName = _rootNameLookup.findRootName(cls, _config);
+        }
         _initWithRootName(jgen, rootName);
-        super.serializeValue(jgen, value);
-    }
+        final boolean asArray = Collection.class.isAssignableFrom(cls) ||
+                (cls.isArray() && cls != byte[].class);
+        if (asArray) {
+            _startRootArray(jgen, rootName);
+        }
+
+        // From super-class implementation
+        final JsonSerializer<Object> ser = findTypedValueSerializer(cls, true, null);
+        try {
+            ser.serialize(value, jgen, this);
+        } catch (IOException ioe) { // As per [JACKSON-99], pass IOException and subtypes as-is
+            throw ioe;
+        } catch (Exception e) { // but wrap RuntimeExceptions, to get path information
+            String msg = e.getMessage();
+            if (msg == null) {
+                msg = "[no message for "+e.getClass().getName()+"]";
+            }
+            throw new JsonMappingException(msg, e);
+        }
+        // end of super-class implementation
 
+        if (asArray) {
+            jgen.writeEndObject();
+        }
+    }
+
     @Override
     public void serializeValue(JsonGenerator jgen, Object value, JavaType rootType)
         throws IOException, JsonProcessingException
     {
-        QName rootName = _rootNameLookup.findRootName(rootType, _config);
+        if (value == null) {
+            _serializeNull(jgen);
+            return;
+        }
+        QName rootName = _rootNameFromConfig();
+        if (rootName == null) {
+            rootName = _rootNameLookup.findRootName(rootType, _config);
+        }
         _initWithRootName(jgen, rootName);
-        super.serializeValue(jgen, value, rootType);
-    }
+        final boolean asArray = TypeUtil.isIndexedType(rootType);
+        if (asArray) {
+            _startRootArray(jgen, rootName);
+        }
 
+        final JsonSerializer<Object> ser = findTypedValueSerializer(rootType, true, null);
+        // From super-class implementation
+        try {
+            ser.serialize(value, jgen, this);
+        } catch (IOException ioe) { // no wrapping for IO (and derived)
+            throw ioe;
+        } catch (Exception e) { // but others do need to be, to get path etc
+            String msg = e.getMessage();
+            if (msg == null) {
+                msg = "[no message for "+e.getClass().getName()+"]";
+            }
+            throw new JsonMappingException(msg, e);
+        }
+        // end of super-class implementation
+
+        if (asArray) {
+            jgen.writeEndObject();
+        }
+    }
+
     // @since 2.1
     @Override
     public void serializeValue(JsonGenerator jgen, Object value, JavaType rootType,
             JsonSerializer<Object> ser)
         throws IOException, JsonGenerationException
     {
-        QName rootName = _rootNameLookup.findRootName(rootType, _config);
+        if (value == null) {
+            _serializeNull(jgen);
+            return;
+        }
+        QName rootName = _rootNameFromConfig();
+        if (rootName == null) {
+            rootName = _rootNameLookup.findRootName(rootType, _config);
+        }
         _initWithRootName(jgen, rootName);
-        super.serializeValue(jgen, value, rootType, ser);
+        final boolean asArray = TypeUtil.isIndexedType(rootType);
+        if (asArray) {
+            _startRootArray(jgen, rootName);
+        }
+        if (ser == null) {
+            ser = findTypedValueSerializer(rootType, true, null);
+        }
+        // From super-class implementation
+        try {
+            ser.serialize(value, jgen, this);
+        } catch (IOException ioe) { // no wrapping for IO (and derived)
+            throw ioe;
+        } catch (Exception e) { // but others do need to be, to get path etc
+            String msg = e.getMessage();
+            if (msg == null) {
+                msg = "[no message for "+e.getClass().getName()+"]";
+            }
+            throw new JsonMappingException(msg, e);
+        }
+        // end of super-class implementation
+        if (asArray) {
+            jgen.writeEndObject();
+        }
     }
-
+
+    protected void _startRootArray(JsonGenerator jgen, QName rootName)
+        throws IOException, JsonProcessingException
+    {
+        jgen.writeStartObject();
+        // Could repeat root name, but what's the point? How to customize?
+        ((ToXmlGenerator) jgen).writeFieldName("item");
+    }    
+
+    @Override
+    protected void _serializeNull(JsonGenerator jgen)
+            throws IOException, JsonProcessingException
+    {
+        _initWithRootName(jgen, ROOT_NAME_FOR_NULL);
+        super.serializeValue(jgen, null);
+    }
+
     protected void _initWithRootName(JsonGenerator jgen, QName rootName)
             throws IOException, JsonProcessingException
     {
@@ -103,7 +211,7 @@ protected void _initWithRootName(JsonGenerator jgen, QName rootName)
         }
         xgen.initGenerator();
         String ns = rootName.getNamespaceURI();
-        /* [Issue-26] If we just try writing root element with namespace,
+        /* [Issue#26] If we just try writing root element with namespace,
          * we will get an explicit prefix. But we'd rather use the default
          * namespace, so let's try to force that.
          */
@@ -115,4 +223,10 @@ protected void _initWithRootName(JsonGenerator jgen, QName rootName)
             }
         }
     }
+
+    protected QName _rootNameFromConfig()
+    {
+        String name = _config.getRootName();
+        return (name == null) ? null : new QName(name);
+    }
 }

src/test/java/com/fasterxml/jackson/dataformat/xml/XmlTestBase.java

@@ -274,10 +274,14 @@ protected String readAll(File f) throws IOException
         return sb.toString();
     }
 
-    public String jaxbSerialized(Object ob) throws Exception
+    public String jaxbSerialized(Object ob, Class<?>... classes) throws Exception
     {
         StringWriter sw = new StringWriter();
-        javax.xml.bind.JAXB.marshal(ob, sw);
+        if (classes.length == 0) {
+            javax.xml.bind.JAXB.marshal(ob, sw);
+        } else {
+            javax.xml.bind.JAXBContext.newInstance(classes).createMarshaller().marshal(ob, sw);
+        }
         sw.close();
         return sw.toString();
     }

src/test/java/com/fasterxml/jackson/dataformat/xml/failing/TestUnwrappedRootList.java

@@ -3,6 +3,7 @@
 import java.util.*;
 
 import com.fasterxml.jackson.databind.AnnotationIntrospector;
+import com.fasterxml.jackson.databind.JavaType;
 import com.fasterxml.jackson.databind.introspect.JacksonAnnotationIntrospector;
 import com.fasterxml.jackson.dataformat.xml.*;
 
@@ -68,13 +69,35 @@ public void testListSerialization() throws Exception
         l.add(r2);
 
         // to see what JAXB might do, uncomment:
-//        System.out.println("By JAXB: "+jaxbSerialized(l));
+//System.out.println("By JAXB: "+jaxbSerialized(l)); //  ArrayList.class, SampleResource.class));
 
-        String result = xmlMapper.writeValueAsString(l);
-        assertNotNull(result);
+        String xml = xmlMapper
+            .writerWithDefaultPrettyPrinter()
+            .withRootName("RootList")
+            .writeValueAsString(l)
+            .trim();
 
-        // TODO: verify actual contents
+        // first trivial sanity checks
+        assertNotNull(xml);
+        if (xml.indexOf("<RootList>") < 0) {
+            fail("Unexpected output: should have <RootList> as root element, got: "+xml);
+        }
+
+        // and then try reading back
+        JavaType resListType = xmlMapper.getTypeFactory()
+                .constructCollectionType(List.class, SampleResource.class);
+        Object ob = xmlMapper.reader(resListType).readValue(xml);
+        assertNotNull(ob);
+
+//      System.err.println("XML -> "+xmlMapper.writerWithDefaultPrettyPrinter().writeValueAsString(ob));
 
-//        assertEquals("<x></x>", result);
+        assertTrue(ob instanceof List);
+        List<?> resultList = (List<?>) ob;
+        assertEquals(2, resultList.size());
+        assertEquals(SampleResource.class, resultList.get(0).getClass());
+        assertEquals(SampleResource.class, resultList.get(1).getClass());
+        SampleResource rr = (SampleResource) resultList.get(1);
+        assertEquals("William", rr.getName());
+
     }
 }