Added an automatic setting to the PojoCodecProvider

Automatically creates a PojoCodec for any unseen class that contains
serializable / deserializable properties.

JAVA-2567

Author: rozza

bson/src/main/org/bson/codecs/pojo/AutomaticPojoCodec.java

@@ -0,0 +1,69 @@
+/*
+ * Copyright 2017 MongoDB, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.bson.codecs.pojo;
+
+import org.bson.BsonReader;
+import org.bson.BsonWriter;
+import org.bson.codecs.DecoderContext;
+import org.bson.codecs.EncoderContext;
+import org.bson.codecs.configuration.CodecConfigurationException;
+
+import static java.lang.String.format;
+
+final class AutomaticPojoCodec<T> extends PojoCodec<T> {
+    private final PojoCodec<T> pojoCodec;
+
+    AutomaticPojoCodec(final PojoCodec<T> pojoCodec) {
+        this.pojoCodec = pojoCodec;
+    }
+
+    @Override
+    public T decode(final BsonReader reader, final DecoderContext decoderContext) {
+        try {
+            return pojoCodec.decode(reader, decoderContext);
+        } catch (CodecConfigurationException e) {
+            throw new CodecConfigurationException(
+                    format("An exception occurred when decoding using the AutomaticPojoCodec.%n"
+                            + "Decoding into a '%s' failed with the following exception:%n%n%s%n%n"
+                            + "A custom Codec or PojoCodec may need to be explicitly configured and registered to handle this type.",
+                            pojoCodec.getEncoderClass().getSimpleName(), e.getMessage()), e);
+        }
+    }
+
+    @Override
+    public void encode(final BsonWriter writer, final T value, final EncoderContext encoderContext) {
+        try {
+            pojoCodec.encode(writer, value, encoderContext);
+        } catch (CodecConfigurationException e) {
+            throw new CodecConfigurationException(
+                    format("An exception occurred when encoding using the AutomaticPojoCodec.%n"
+                            + "Encoding a %s: '%s' failed with the following exception:%n%n%s%n%n"
+                            + "A custom Codec or PojoCodec may need to be explicitly configured and registered to handle this type.",
+                            getEncoderClass().getSimpleName(), value, e.getMessage()), e);
+        }
+    }
+
+    @Override
+    public Class<T> getEncoderClass() {
+        return pojoCodec.getEncoderClass();
+    }
+
+    @Override
+    ClassModel<T> getClassModel() {
+        return pojoCodec.getClassModel();
+    }
+}

bson/src/main/org/bson/codecs/pojo/ConventionDefaultsImpl.java

@@ -23,7 +23,7 @@ public void apply(final ClassModelBuilder<?> classModelBuilder) {
             classModelBuilder.discriminatorKey("_t");
         }
         if (classModelBuilder.getDiscriminator() == null && classModelBuilder.getType() != null) {
-            classModelBuilder.discriminator(classModelBuilder.getType().getSimpleName());
+            classModelBuilder.discriminator(classModelBuilder.getType().getName());
         }
 
        for (final PropertyModelBuilder<?> propertyModel : classModelBuilder.getPropertyModelBuilders()) {

bson/src/main/org/bson/codecs/pojo/CreatorExecutable.java

@@ -111,7 +111,7 @@ CodecConfigurationException getError(final String msg) {
 
     void checkHasAnExecutable() {
         if (constructor == null && method == null) {
-            throw new CodecConfigurationException(format("Cannot find a public constructor for '%s'", clazz.getSimpleName()));
+            throw new CodecConfigurationException(format("Cannot find a public constructor for '%s'.", clazz.getSimpleName()));
         }
     }
 

bson/src/main/org/bson/codecs/pojo/DiscriminatorLookup.java

@@ -35,7 +35,7 @@ final class DiscriminatorLookup {
         this.packages = packages;
     }
 
-    Class<?> lookup(final String discriminator) {
+    public Class<?> lookup(final String discriminator) {
         if (discriminatorClassMap.containsKey(discriminator)) {
             return discriminatorClassMap.get(discriminator);
         }
@@ -53,6 +53,12 @@ Class<?> lookup(final String discriminator) {
         return clazz;
     }
 
+    void addClassModel(final ClassModel<?> classModel) {
+        if (classModel.getDiscriminator() != null) {
+            discriminatorClassMap.put(classModel.getDiscriminator(), classModel.getType());
+        }
+    }
+
     private Class<?> getClassForName(final String discriminator) {
         Class<?> clazz = null;
         try {

bson/src/main/org/bson/codecs/pojo/LazyPojoCodec.java

@@ -25,18 +25,16 @@
 
 import java.util.concurrent.ConcurrentMap;
 
-class LazyPojoCodec<T> implements Codec<T> {
+class LazyPojoCodec<T> extends PojoCodec<T> {
     private final ClassModel<T> classModel;
-    private final PojoCodecProvider codecProvider;
     private final CodecRegistry registry;
     private final DiscriminatorLookup discriminatorLookup;
     private final ConcurrentMap<ClassModel<?>, Codec<?>> codecCache;
-    private volatile PojoCodec<T> pojoCodec;
+    private volatile PojoCodecImpl<T> pojoCodec;
 
-    LazyPojoCodec(final ClassModel<T> classModel, final PojoCodecProvider codecProvider, final CodecRegistry registry,
-                  final DiscriminatorLookup discriminatorLookup, final ConcurrentMap<ClassModel<?>, Codec<?>> codecCache) {
+    LazyPojoCodec(final ClassModel<T> classModel, final CodecRegistry registry, final DiscriminatorLookup discriminatorLookup,
+                  final ConcurrentMap<ClassModel<?>, Codec<?>> codecCache) {
         this.classModel = classModel;
-        this.codecProvider = codecProvider;
         this.registry = registry;
         this.discriminatorLookup = discriminatorLookup;
         this.codecCache = codecCache;
@@ -59,8 +57,13 @@ public T decode(final BsonReader reader, final DecoderContext decoderContext) {
 
     private Codec<T> getPojoCodec() {
         if (pojoCodec == null) {
-            pojoCodec = new PojoCodec<T>(classModel, codecProvider, registry, discriminatorLookup, codecCache, true);
+            pojoCodec = new PojoCodecImpl<T>(classModel, registry, discriminatorLookup, codecCache, true);
         }
         return pojoCodec;
     }
+
+    @Override
+    ClassModel<T> getClassModel() {
+        return classModel;
+    }
 }