Added support for providing field name overrides when reading and writing JSON documents

Author: aantono

.gitignore

@@ -1 +1,2 @@
 /target
+protobuf-codec.i*

pom.xml

@@ -22,7 +22,7 @@ http://maven.apache.org/maven-v4_0_0.xsd">
 		<dependency>
 			<groupId>com.google.protobuf</groupId>
 			<artifactId>protobuf-java</artifactId>
-			<version>2.3.0</version>
+			<version>2.4.1</version>
 		</dependency>
 		<dependency>
 			<groupId>org.codehaus.jackson</groupId>

protobuf-codec-core/.gitignore

@@ -1 +1,2 @@
 /target
+protobuf-codec-core.iml

protobuf-codec-core/src/main/java/protobuf/codec/AbstractCodec.java

@@ -177,6 +177,51 @@ public static  Builder mergeUnknownFieldsFromString(Builder builder,
 	public Map<Feature, Object> getAllFeaturesSet() {
 		return Collections.unmodifiableMap(featureMap);
 	}
+
+    public static boolean stripFieldNameUnderscores(Map<Feature, Object> featureMap) {
+        return Boolean.TRUE.equals(featureMap.get(Feature.STRIP_FIELD_NAME_UNDERSCORES));
+    }
+
+    public static String stripFieldName(String fieldName, Map<Feature, Object> featureMap) {
+        if (stripFieldNameUnderscores(featureMap) && fieldName.endsWith("_")) {
+            String processed = fieldName;
+            boolean modified = false;
+            if (processed.startsWith("_")) {
+                processed = processed.substring(1);
+                modified = true;
+            }
+            if (processed.endsWith("_")) {
+                processed = processed.substring(0, processed.length()-1);
+                modified = true;
+            }
+            if (modified) {
+                return stripFieldName(processed, featureMap);
+            } else {
+                return processed;
+            }
+        }
+        return fieldName;
+    }
+
+    public static String substituteFieldNameForWriting(String fieldName, Map<Feature, Object> featureMap) {
+        return substituteFieldName(fieldName, false, featureMap);
+    }
+    public static String substituteFieldNameForReading(String fieldName, Map<Feature, Object> featureMap) {
+        return substituteFieldName(fieldName, true, featureMap);
+    }
+    public static String substituteFieldName(String fieldName, boolean read, Map<Feature, Object> featureMap) {
+        Map<String, String> aliases = Collections.EMPTY_MAP;
+        if (read && featureMap.containsKey(Feature.FIELD_NAME_READ_SUBSTITUTES)) {
+            aliases = (Map<String, String>) featureMap.get(Feature.FIELD_NAME_READ_SUBSTITUTES);
+        } else if (featureMap.containsKey(Feature.FIELD_NAME_WRITE_SUBSTITUTES)) {
+            aliases = (Map<String, String>) featureMap.get(Feature.FIELD_NAME_WRITE_SUBSTITUTES);
+        }
+        if (aliases.containsKey(fieldName)) {
+            return aliases.get(fieldName);
+        } else {
+            return fieldName;
+        }
+    }
 
 
 	/**
@@ -194,7 +239,7 @@ public  static boolean isExtensionFieldName(String fieldName,Map<Feature, Object
 	 * Returns the field protobuf extn field name for the provided field name.
 	 * @param fieldName the provided field name
 	 * @return the protobuf field name = <field_name> for "extension_field_name>"
-	 * @throws IllegalArgumentException if {@link #isExtensionFieldName(String)} returns false
+	 * @throws IllegalArgumentException if {@link #isExtensionFieldName(String, java.util.Map)} returns false
 	 */
 	public static String parseExtensionFieldName(String fieldName,Map<Feature, Object> featureMap){
 		if(!isExtensionFieldName(fieldName,featureMap)){

protobuf-codec-core/src/main/java/protobuf/codec/Codec.java

@@ -38,12 +38,12 @@ public interface Codec {
 	 * Write this Message {@link Message} to the provided output stream. The underlying stream is not closed by default, 
 	 * user {@link Feature#CLOSE_STREAM} for the required settings.
 	 * The default values are not written out, the reason being that the client should be aware of the protobuf schema.
-	 * The {@link UnknownFieldSet} are written out on whether the {@link Feature#UNKNOWN_FIELDS} is set. By default, {@link UnknownFieldSet}
+	 * The {@link UnknownFieldSet} are written out on whether the {@link Feature#UNKNOWN_FIELD_ELEM_NAME} is set. By default, {@link UnknownFieldSet}
 	 * is written out Check the codec implementation on how the unknown field set is written out.
 	 * Extension fields are written out and the naming depends on the {@link Feature#EXTENSION_FIELD_NAME_PREFIX} set. 
 	 * If an extension field  not provided in the registry is encountered that field is skipped.
 	 * @param message the {@link Message}
-	 * @param os the output stream
+	 * @param writer the output stream writer
 	 * @throws IOException
 	 * @throws IllegalArgumentException if the provided message is not initialized 
 	 */
@@ -55,12 +55,12 @@ public interface Codec {
 	 * In case null values encountered are skipped since protobuf does not support null values yet 
 	 * ( http://code.google.com/p/protobuf/issues/detail?id=57 )
 	 * The default values are not written out, the reason being that the client should be aware of the protobuf schema.
-	 * The {@link UnknownFieldSet} are read in depending on whether the {@link Feature#UNKNOWN_FIELDS} is set. By default, {@link UnknownFieldSet}
+	 * The {@link UnknownFieldSet} are read in depending on whether the {@link Feature#UNKNOWN_FIELD_ELEM_NAME} is set. By default, {@link UnknownFieldSet}
 	 * is read in. Check the codec implementation on how the unknown field need to be passed in.
 	 * Extension field names depend on {@link Feature#EXTENSION_FIELD_NAME_PREFIX}
 	 * If an extension field  not provided in the registry is encountered that field is skipped.
 	 * @param messageType the {@link Class} corresponding to the {@link Message} the stream needs to be read into
-	 * @param in the input stream
+	 * @param reader the input stream reader
 	 * @return the {@link Message}
 	 * @throws IOException
 	 */
@@ -76,7 +76,7 @@ public interface Codec {
 	 * is identified to be an extension field, but a corresponding mapping is not found in the registry, then 
 	 * the field is skipped.
 	 * @param messageType the {@link Class} corresponding to the {@link Message} the stream needs to be read into
-	 * @param in the input stream
+	 * @param reader the input stream reader
 	 * @param extnRegistry the extension registry which contains the defn for extension fields.
 	 * @return the {@link Message}
 	 * @throws IOException
@@ -114,7 +114,7 @@ public interface Codec {
 	 * @param extnRegistry the extension registry
 	 * @return
 	 * @throws IOException
-	 * @see {@link #toMessage(Reader)}
+	 * @see {@link #toMessage(Class, Reader)}
 	 */
 	<T extends Message> T toMessage(Class<T> messageType,InputStream in,ExtensionRegistry extnRegistry) throws IOException;
 
@@ -162,6 +162,11 @@ public enum Feature{
 		/** Unknown field element name */
 		UNKNOWN_FIELD_ELEM_NAME,
 		/** Extension field name prefix */
-		EXTENSION_FIELD_NAME_PREFIX;
+		EXTENSION_FIELD_NAME_PREFIX,
+        /** Strip leading and trailing underscores from field names */
+        STRIP_FIELD_NAME_UNDERSCORES,
+        /** Provide field name substitutes for reading and writing from/to a protobuf stream*/
+        FIELD_NAME_READ_SUBSTITUTES,
+        FIELD_NAME_WRITE_SUBSTITUTES;
 	}
 }

protobuf-codec-json/.gitignore

@@ -1,2 +1,2 @@
-/target
 /target
+protobuf-codec-json.iml

protobuf-codec-json/src/main/java/protobuf/codec/json/JacksonJsonReader.java

@@ -49,6 +49,8 @@ private static Builder parseObject(Builder builder, JsonParser parser,ExtensionR
 			JsonToken currToken = parser.getCurrentToken();
 			assert (currToken.equals(JsonToken.FIELD_NAME));
 			String fieldName = parser.getCurrentName();
+            fieldName = AbstractCodec.stripFieldName(fieldName, featureMap);
+            fieldName = AbstractCodec.substituteFieldNameForReading(fieldName, featureMap);
 			FieldDescriptor field=null;
 			if(JsonCodec.isExtensionFieldName(fieldName,featureMap)){
 				fieldName=JsonCodec.parseExtensionFieldName(fieldName,featureMap);

protobuf-codec-json/src/main/java/protobuf/codec/json/JacksonJsonWriter.java

@@ -43,6 +43,7 @@ public static void generateJSONFields(Message message,JsonGenerator generator,Ma
 			Map.Entry<FieldDescriptor, Object> record = iterator.next();
 			FieldDescriptor field = record.getKey();
 			String fieldName = field.isExtension() ?JsonCodec.getExtensionFieldName(field.getName(),featureMap): field.getName(); // If extn field? box
+            fieldName = AbstractCodec.substituteFieldNameForWriting(fieldName, featureMap);
 			Object value = record.getValue();
 			if (field.isRepeated()) {
 				generator.writeArrayFieldStart(fieldName);

protobuf-codec-json/src/main/java/protobuf/codec/json/JsonCodec.java

@@ -4,6 +4,7 @@
 import java.io.InputStream;
 import java.io.Reader;
 import java.io.Writer;
+import java.util.Map;
 
 import org.codehaus.jackson.JsonFactory;
 import org.codehaus.jackson.JsonGenerator;
@@ -21,8 +22,8 @@
  * Json-protobuf serializer/deserializer.Relies on jackson as the underlying parser.
  * Supports {@link UnknownFieldSet}, extension field names prefixed with {@link Feature#EXTENSION_FIELD_NAME_PREFIX} and a "-"/
  * ex: "extension-name" idenfies an extension file by type name
- * In case the {@link Feature#UNKNOWN_FIELDS} is enabled ( this feature is enabled by default) each json object in 
- * could contain a field by name "unknownfields" or whatever value the {@value Feature#UNKNOWN_FIELD_ELEM_NAME} is
+ * In case the {@link Feature#UNKNOWN_FIELD_ELEM_NAME} is enabled ( this feature is enabled by default) each json object in
+ * could contain a field by name "unknownfields" or whatever value the {@value Feature.UNKNOWN_FIELD_ELEM_NAME} is
  * set to. The value of this field is hex encoded byte string.
  *
  * @author sijuv
@@ -37,18 +38,18 @@ public JsonCodec(){
 
 	/**
 	 * Fills in a message from the data from the stream, The stream is not closed once the message is read in, the extn field names 
-	 * need to be boxed. {@link UnknownFieldSet}  passed is passed in the field defined by {@value Feature#UNKNOWN_FIELD_ELEM_NAME}. 
+	 * need to be boxed. {@link UnknownFieldSet}  passed is passed in the field defined by {@value Feature.UNKNOWN_FIELD_ELEM_NAME}.
 	 * The {@link UnknownFieldSet} provided is parsed in only if the {@link Feature#SUPPORT_UNKNOWN_FIELDS} is enabled. 
 	 * The value passed in as unknown field should be corresponding hex encoded byte[]
 	 * The {@link Feature#EXTENSION_FIELD_NAME_PREFIX} controlls how the extension field names need to be.
 	 * @param builder the message builder
 	 * @param reader the input stream,
 	 * @param extnRegistry the extension registry to use
 	 * @see Codec#toMessage(Class, Reader)
-	 * @see AbstractCodec#mergeUnknownFieldsFromHexString(Builder, ExtensionRegistry, String)
+	 * @see AbstractCodec#mergeUnknownFieldsFromString(Builder, ExtensionRegistry, String)
 	 */
 	@Override
-	protected Message  readFromStream(Builder builder, Reader reader,ExtensionRegistry extnRegistry)throws IOException {
+	protected Message readFromStream(Builder builder, Reader reader,ExtensionRegistry extnRegistry)throws IOException {
 		JsonFactory jsonFactory=new JsonFactory();
 		JsonParser parser=jsonFactory.createJsonParser(reader);
 		return JacksonJsonReader.parse(builder, parser,extnRegistry,getAllFeaturesSet());
@@ -58,12 +59,12 @@ protected Message  readFromStream(Builder builder, Reader reader,ExtensionRegist
 	 * Writes out the messages as a json object the provided stream.
 	 * The stream is not closed once the message is written out. {@link UnknownFieldSet} is serialized out as a hex byte string.
 	 * @param message the provided protobuf message
-	 * @param os the output stream onto which the message is written to.
-	 * @see Codec#toMessage(InputStream)
+	 * @param writer the output stream writer onto which the message is written to.
+	 * @see Codec#toMessage(Class, InputStream)
 	 * Sample response:<br>
 	 * {"id":1,"name":"elton john","extension-bar":1,"extension-id":24,"extension-place":"london"}
 	 * bar and place are extension fields.
-	 * @see AbstractCodec#encodeUnknownFieldsToHexString(UnknownFieldSet)
+	 * @see AbstractCodec#encodeUnknownFieldsToString(UnknownFieldSet)
 	 * 
 	 */
 	@Override
@@ -81,6 +82,7 @@ public void validateAndSetFeature(Feature feature, Object value) {
 		case SUPPORT_UNKNOWN_FIELDS:
 		case PRETTY_PRINT:
 		case CLOSE_STREAM:
+        case STRIP_FIELD_NAME_UNDERSCORES:
 			if(!(Boolean.TRUE.equals(value)||Boolean.FALSE.equals(value))){
 				throw new IllegalArgumentException(String.format("Unsupported value [%s] for feature [%s]",value,feature));
 			}
@@ -92,6 +94,12 @@ public void validateAndSetFeature(Feature feature, Object value) {
 				throw new IllegalArgumentException(String.format("Feature [%s] expected to be a non null string",feature));
 			}
 			break;
+        case FIELD_NAME_READ_SUBSTITUTES:
+        case FIELD_NAME_WRITE_SUBSTITUTES:
+            if(value==null || !(Map.class).isAssignableFrom(value.getClass())) {
+                throw new IllegalArgumentException(String.format("Feature [%s] expected to be a non null Map<String,String>", feature));
+            }
+            break;
 		default:
 			throw new IllegalArgumentException(String.format("Unsupported feature [%s]",feature));
 		}	

protobuf-codec-json/src/test/java/protobuf/codec/json/JsonCodecTest.java

@@ -7,6 +7,8 @@
 import java.io.StringReader;
 import java.io.StringWriter;
 import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Map;
 
 import org.apache.commons.codec.binary.Base64;
 import org.codehaus.jackson.JsonFactory;
@@ -308,4 +310,36 @@ public void testExtensionObjects()throws Exception{
 		assertEquals(foo1, foo2);
 	}
 
+    @Test
+    public void testForFieldNameReplacements() throws Exception {
+        Foo obj = Foo.newBuilder().setId(1).setName("FooName").build();
+
+        StringWriter writer = new StringWriter();
+        JsonGenerator generator = new JsonFactory().createJsonGenerator(writer);
+        generator.writeStartObject();
+        generator.writeNumberField("_id", 1);
+        generator.writeStringField("name_", "FooName");
+        generator.writeEndObject();
+        generator.close();
+
+        Codec codec = new JsonCodec();
+        Map<String, String> replaces = new HashMap<String, String>();
+        replaces.put("name", "name_");
+        replaces.put("id", "_id");
+        codec.setFeature(Codec.Feature.FIELD_NAME_WRITE_SUBSTITUTES, replaces);
+        replaces = new HashMap<String, String>();
+        replaces.put("name_", "name");
+        replaces.put("_id", "id");
+        codec.setFeature(Codec.Feature.FIELD_NAME_READ_SUBSTITUTES, replaces);
+
+        StringWriter out = new StringWriter();
+        codec.fromMessage(obj, out);
+
+        assertEquals(writer.toString(), out.toString());
+
+        Foo msg = codec.toMessage(Foo.class, new StringReader(out.toString()));
+
+        assertEquals(obj, msg);
+    }
+
 }

protobuf-codec-xml/.gitignore

@@ -1 +1,2 @@
 /target
+protobuf-codec-xml.iml