Overhauled and added documentation.

build.gradle

@@ -2,16 +2,13 @@ buildscript {
     ext {
         // external dependency versions
         groovyVersion = '2.4.5'
-        gradleVersion = '2.9'
-        jacksonVersion = '2.6.7'
-        slf4jVersion = '1.7.12'
+        gradleVersion = '2.14.1'
+        jacksonVersion = '[2.2,)'
         spockVersion = '1.0-groovy-2.4'
 
         // external dependencies
         groovy = "org.codehaus.groovy:groovy-all:${groovyVersion}"
         jacksonDatabind = "com.fasterxml.jackson.core:jackson-databind:${jacksonVersion}"
-        slf4jApi = "org.slf4j:slf4j-api:${slf4jVersion}"
-        slf4jSimple = "org.slf4j:slf4j-simple:${slf4jVersion}"
         spockCore = "org.spockframework:spock-core:${spockVersion}"
     }
 
@@ -22,12 +19,11 @@ buildscript {
 
 
 task wrapper(type: Wrapper) {
-    gradleVersion = gradleVersion
+    gradleVersion = this.gradleVersion
 }
 
 
 group = 'com.github.jonpeterson'
-version = '1.0.0-SNAPSHOT'
 
 apply plugin: 'java'
 apply plugin: 'groovy'
@@ -41,9 +37,7 @@ repositories {
 
 dependencies {
     compile jacksonDatabind
-    compile slf4jApi
 
     testCompile groovy
-    testCompile slf4jSimple
     testCompile spockCore
 }

gradle.properties

@@ -0,0 +1 @@
+version=1.0.0-SNAPSHOT

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
-#Thu Jul 28 10:56:21 EDT 2016
+#Sun Jul 31 02:03:03 EDT 2016
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-2.9-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-2.14.1-bin.zip

gradlew

@@ -6,12 +6,30 @@
 ##
 ##############################################################################
 
-# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-DEFAULT_JVM_OPTS=""
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
 
 APP_NAME="Gradle"
 APP_BASE_NAME=`basename "$0"`
 
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS=""
+
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD="maximum"
 
@@ -30,6 +48,7 @@ die ( ) {
 cygwin=false
 msys=false
 darwin=false
+nonstop=false
 case "`uname`" in
   CYGWIN* )
     cygwin=true
@@ -40,26 +59,11 @@ case "`uname`" in
   MINGW* )
     msys=true
     ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
 esac
 
-# Attempt to set APP_HOME
-# Resolve links: $0 may be a link
-PRG="$0"
-# Need this for relative symlinks.
-while [ -h "$PRG" ] ; do
-    ls=`ls -ld "$PRG"`
-    link=`expr "$ls" : '.*-> \(.*\)$'`
-    if expr "$link" : '/.*' > /dev/null; then
-        PRG="$link"
-    else
-        PRG=`dirname "$PRG"`"/$link"
-    fi
-done
-SAVED="`pwd`"
-cd "`dirname \"$PRG\"`/" >/dev/null
-APP_HOME="`pwd -P`"
-cd "$SAVED" >/dev/null
-
 CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
 
 # Determine the Java command to use to start the JVM.
@@ -85,7 +89,7 @@ location of your Java installation."
 fi
 
 # Increase the maximum file descriptors if we can.
-if [ "$cygwin" = "false" -a "$darwin" = "false" ] ; then
+if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
     MAX_FD_LIMIT=`ulimit -H -n`
     if [ $? -eq 0 ] ; then
         if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then

gradlew.bat

@@ -8,14 +8,14 @@
 @rem Set local scope for the variables with windows NT shell
 if "%OS%"=="Windows_NT" setlocal
 
-@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-set DEFAULT_JVM_OPTS=
-
 set DIRNAME=%~dp0
 if "%DIRNAME%" == "" set DIRNAME=.
 set APP_BASE_NAME=%~n0
 set APP_HOME=%DIRNAME%
 
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS=
+
 @rem Find java.exe
 if defined JAVA_HOME goto findJavaFromJavaHome
 
@@ -46,7 +46,7 @@ echo location of your Java installation.
 goto fail
 
 :init
-@rem Get command-line arguments, handling Windowz variants
+@rem Get command-line arguments, handling Windows variants
 
 if not "%OS%" == "Windows_NT" goto win9xME_args
 if "%@eval[2+2]" == "4" goto 4NT_args

src/main/java/com/github/jonpeterson/jackson/module/versioning/JsonVersionedModel.java

@@ -0,0 +1,62 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Jon Peterson
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.github.jonpeterson.jackson.module.versioning;
+
+import com.fasterxml.jackson.annotation.JacksonAnnotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Specifies converter for used in resolving versioning for pre-deserialized JSON.
+ */
+@Target({ElementType.TYPE})
+@Retention(RetentionPolicy.RUNTIME)
+@JacksonAnnotation
+public @interface JsonVersionedModel {
+
+    /**
+     * @return the current version of the model; this will be added to the serialized model's {@link #propertyName()}.
+     */
+    String currentVersion();
+
+    /**
+     * @return class of the converter to use when resolving versioning.
+     */
+    Class<? extends VersionedModelConverter> converterClass();
+
+    /**
+     * @return whether to always send JSON data to converter, even when the data is the same version as the
+     *         {@link #currentVersion()}.
+     */
+    boolean alwaysConvert() default false;
+
+    /**
+     * @return name of property in which the model's version is stored in JSON.
+     */
+    String propertyName() default "modelVersion";
+}

src/main/java/com/github/jonpeterson/jackson/module/versioning/VersionedModelConverter.java

@@ -0,0 +1,17 @@
+package com.github.jonpeterson.jackson.module.versioning;
+
+import com.fasterxml.jackson.databind.node.ObjectNode;
+
+/**
+ * Converter used by {@link JsonVersionedModel} for resolving model versioning.
+ */
+public interface VersionedModelConverter {
+
+    /**
+     * Updates JSON data before deserialization to model.
+     *
+     * @param modelVersion version of data
+     * @param modelData    JSON data to update
+     */
+    void convert(String modelVersion, ObjectNode modelData);
+}

src/main/java/com/github/jonpeterson/jackson/module/versioning/VersionedModelDeserializer.java

@@ -1,59 +1,62 @@
 package com.github.jonpeterson.jackson.module.versioning;
 
 import com.fasterxml.jackson.core.JsonParser;
-import com.fasterxml.jackson.core.JsonProcessingException;
-import com.fasterxml.jackson.core.TreeNode;
-import com.fasterxml.jackson.databind.*;
+import com.fasterxml.jackson.databind.DeserializationContext;
+import com.fasterxml.jackson.databind.JsonMappingException;
+import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.deser.ResolvableDeserializer;
 import com.fasterxml.jackson.databind.deser.std.StdDeserializer;
 import com.fasterxml.jackson.databind.node.ObjectNode;
 import com.fasterxml.jackson.databind.node.TreeTraversingParser;
 
 import java.io.IOException;
-import java.lang.reflect.ParameterizedType;
 
-public class VersionedModelDeserializer extends StdDeserializer<VersionedModel> implements ResolvableDeserializer {
-    private final JsonDeserializer<VersionedModel> delegateDeserializer;
-    private final VersionedModelDataTransformer transformer;
+class VersionedModelDeserializer<T> extends StdDeserializer<T> implements ResolvableDeserializer {
+    private final StdDeserializer<T> delegate;
+    private final JsonVersionedModel jsonVersionedModel;
+    private final VersionedModelConverter converter;
 
-    protected VersionedModelDeserializer(JsonDeserializer<VersionedModel> delegateDeserializer, VersionedModelDataTransformer transformer) {
-        super(VersionedModel.class);
+    VersionedModelDeserializer(StdDeserializer<T> delegate, JsonVersionedModel jsonVersionedModel) {
+        super(delegate.getValueType());
 
-        this.delegateDeserializer = delegateDeserializer;
-        this.transformer = transformer;
+        this.delegate = delegate;
+        this.jsonVersionedModel = jsonVersionedModel;
+
+        try {
+            this.converter = jsonVersionedModel.converterClass().newInstance();
+        } catch(Exception e) {
+            throw new RuntimeException("unable to create instance of converter '" + jsonVersionedModel.converterClass().getName() + "'", e);
+        }
     }
 
     @Override
     public void resolve(DeserializationContext context) throws JsonMappingException {
-        ((ResolvableDeserializer)delegateDeserializer).resolve(context);
+        if(delegate instanceof ResolvableDeserializer)
+            ((ResolvableDeserializer)delegate).resolve(context);
     }
 
     @Override
-    public VersionedModel deserialize(JsonParser parser, DeserializationContext context) throws IOException, JsonProcessingException {
-        TreeNode treeNode = parser.readValueAsTree();
+    public T deserialize(JsonParser parser, DeserializationContext context) throws IOException {
+        JsonNode jsonNode = parser.readValueAsTree();
 
-        if(!(treeNode instanceof ObjectNode))
+        if(!(jsonNode instanceof ObjectNode))
             throw context.mappingException("value must be a JSON object");
 
-        ObjectNode objectNode = (ObjectNode)treeNode;
+        ObjectNode modelData = (ObjectNode)jsonNode;
 
-        JsonNode modelVersionNode = objectNode.remove(VersionedModel.MODEL_VERSION_PROPERTY);
+        JsonNode modelVersionNode = modelData.remove(jsonVersionedModel.propertyName());
         if(modelVersionNode == null)
-            throw context.mappingException("'" + VersionedModel.MODEL_VERSION_PROPERTY + "' property was not present");
-
-        // DEBUG HERE
-        //Class<?> abc = delegateDeserializer.handledType();
-        //((ParameterizedType)abc.getGenericInterfaces()[0]).getActualTypeArguments()[0]
+            throw context.mappingException("'" + jsonVersionedModel.propertyName() + "' property was not present");
 
         String modelVersion = modelVersionNode.asText();
         if(modelVersion == null)
-            throw context.mappingException("'" + VersionedModel.MODEL_VERSION_PROPERTY + "' property was null");
+            throw context.mappingException("'" + jsonVersionedModel.propertyName() + "' property was null");
 
-        if(transformer != null && !modelVersion.equals(transformer.targetVersion))
-            transformer.transform(modelVersion, objectNode);
+        if(jsonVersionedModel.alwaysConvert() || !modelVersion.equals(jsonVersionedModel.currentVersion()))
+            converter.convert(modelVersion, modelData);
 
-        JsonParser objectNodeParser = new TreeTraversingParser(objectNode);
-        objectNodeParser.nextToken();
-        return delegateDeserializer.deserialize(objectNodeParser, context);
+        JsonParser postInterceptionParser = new TreeTraversingParser(jsonNode, parser.getCodec());
+        postInterceptionParser.nextToken();
+        return delegate.deserialize(postInterceptionParser, context);
     }
-}
+}