Added Pojo id generation

Added IdGenerator to ClassModel to support to Pojos generating
their own id's. Supports both mutable and immutable Pojos. Mutable
Pojos will update their Id property's value.

JAVA-2674

Author: rozza

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

@@ -33,13 +33,14 @@ public final class ClassModel<T> {
     private final boolean discriminatorEnabled;
     private final String discriminatorKey;
     private final String discriminator;
-    private final PropertyModel<?> idProperty;
+    private final IdPropertyModelHolder<?> idPropertyModelHolder;
     private final List<PropertyModel<?>> propertyModels;
     private final Map<String, TypeParameterMap> propertyNameToTypeParameterMap;
 
     ClassModel(final Class<T> clazz, final Map<String, TypeParameterMap> propertyNameToTypeParameterMap,
                final InstanceCreatorFactory<T> instanceCreatorFactory, final Boolean discriminatorEnabled, final String discriminatorKey,
-               final String discriminator, final PropertyModel<?> idProperty, final List<PropertyModel<?>> propertyModels) {
+               final String discriminator, final IdPropertyModelHolder<?> idPropertyModelHolder,
+               final List<PropertyModel<?>> propertyModels) {
         this.name = clazz.getSimpleName();
         this.type = clazz;
         this.hasTypeParameters = clazz.getTypeParameters().length > 0;
@@ -48,7 +49,7 @@ public final class ClassModel<T> {
         this.discriminatorEnabled = discriminatorEnabled;
         this.discriminatorKey = discriminatorKey;
         this.discriminator = discriminator;
-        this.idProperty = idProperty;
+        this.idPropertyModelHolder = idPropertyModelHolder;
         this.propertyModels = propertyModels;
     }
 
@@ -139,7 +140,11 @@ public List<PropertyModel<?>> getPropertyModels() {
      * @return the PropertyModel for the id
      */
     public PropertyModel<?> getIdPropertyModel() {
-        return idProperty;
+        return idPropertyModelHolder != null ? idPropertyModelHolder.getPropertyModel() : null;
+    }
+
+    IdPropertyModelHolder<?> getIdPropertyModelHolder() {
+        return idPropertyModelHolder;
     }
 
     /**
@@ -185,7 +190,8 @@ public boolean equals(final Object o) {
         if (getDiscriminator() != null ? !getDiscriminator().equals(that.getDiscriminator()) : that.getDiscriminator() != null) {
             return false;
         }
-        if (idProperty != null ? !idProperty.equals(that.idProperty) : that.idProperty != null) {
+        if (idPropertyModelHolder != null ? !idPropertyModelHolder.equals(that.idPropertyModelHolder)
+                : that.idPropertyModelHolder != null) {
             return false;
         }
         if (!getPropertyModels().equals(that.getPropertyModels())) {
@@ -205,7 +211,7 @@ public int hashCode() {
         result = 31 * result + (discriminatorEnabled ? 1 : 0);
         result = 31 * result + (getDiscriminatorKey() != null ? getDiscriminatorKey().hashCode() : 0);
         result = 31 * result + (getDiscriminator() != null ? getDiscriminator().hashCode() : 0);
-        result = 31 * result + (idProperty != null ? idProperty.hashCode() : 0);
+        result = 31 * result + (getIdPropertyModelHolder() != null ? getIdPropertyModelHolder().hashCode() : 0);
         result = 31 * result + getPropertyModels().hashCode();
         result = 31 * result + getPropertyNameToTypeParameterMap().hashCode();
         return result;

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

@@ -45,6 +45,7 @@
 public class ClassModelBuilder<T> {
     static final String ID_PROPERTY_NAME = "_id";
     private final List<PropertyModelBuilder<?>> propertyModelBuilders = new ArrayList<PropertyModelBuilder<?>>();
+    private IdGenerator<?> idGenerator;
     private InstanceCreatorFactory<T> instanceCreatorFactory;
     private Class<T> type;
     private Map<String, TypeParameterMap> propertyNameToTypeParameterMap = emptyMap();
@@ -59,6 +60,26 @@ public class ClassModelBuilder<T> {
         configureClassModelBuilder(this, notNull("type", type));
     }
 
+    /**
+     * Sets the IdGenerator for the ClassModel
+     *
+     * @param idGenerator the IdGenerator
+     * @return this
+     * @since 3.10
+     */
+    public ClassModelBuilder<T> idGenerator(final IdGenerator<?> idGenerator) {
+        this.idGenerator = idGenerator;
+        return this;
+    }
+
+    /**
+     * @return the IdGenerator for the ClassModel, or null if not set
+     * @since 3.10
+     */
+    public IdGenerator<?> getIdGenerator() {
+        return idGenerator;
+    }
+
     /**
      * Sets the InstanceCreatorFactory for the ClassModel
      *
@@ -271,10 +292,8 @@ public ClassModel<T> build() {
             }
         }
         validatePropertyModels(type.getSimpleName(), propertyModels);
-
-
         return new ClassModel<T>(type, propertyNameToTypeParameterMap, instanceCreatorFactory, discriminatorEnabled, discriminatorKey,
-                discriminator, idPropertyModel, unmodifiableList(propertyModels));
+                discriminator, IdPropertyModelHolder.create(type, idPropertyModel, idGenerator), unmodifiableList(propertyModels));
     }
 
     @Override

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

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2008-present 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.BsonObjectId;
+import org.bson.types.ObjectId;
+
+final class ConventionObjectIdGeneratorsImpl implements Convention {
+    @Override
+    public void apply(final ClassModelBuilder<?> classModelBuilder) {
+       if (classModelBuilder.getIdGenerator() == null && classModelBuilder.getIdPropertyName() != null) {
+           PropertyModelBuilder<?> idProperty = classModelBuilder.getProperty(classModelBuilder.getIdPropertyName());
+           if (idProperty != null) {
+               Class<?> idType = idProperty.getTypeData().getType();
+               if (classModelBuilder.getIdGenerator() == null && idType.equals(ObjectId.class)) {
+                   classModelBuilder.idGenerator(IdGenerators.OBJECT_ID_GENERATOR);
+               } else if (classModelBuilder.getIdGenerator() == null && idType.equals(BsonObjectId.class)) {
+                   classModelBuilder.idGenerator(IdGenerators.BSON_OBJECT_ID_GENERATOR);
+               }
+           }
+       }
+    }
+}

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

@@ -42,14 +42,14 @@ && isPrivate(propertyMetaData.getField().getModifiers())) {
 
     @SuppressWarnings("unchecked")
     private <T> void setPropertyAccessor(final PropertyModelBuilder<T> propertyModelBuilder) {
-        propertyModelBuilder.propertyAccessor(new PrivateProperyAccessor<T>(
+        propertyModelBuilder.propertyAccessor(new PrivatePropertyAccessor<T>(
                 (PropertyAccessorImpl<T>) propertyModelBuilder.getPropertyAccessor()));
     }
 
-    private static final class PrivateProperyAccessor<T> implements PropertyAccessor<T> {
+    private static final class PrivatePropertyAccessor<T> implements PropertyAccessor<T> {
         private final PropertyAccessorImpl<T> wrapped;
 
-        private PrivateProperyAccessor(final PropertyAccessorImpl<T> wrapped) {
+        private PrivatePropertyAccessor(final PropertyAccessorImpl<T> wrapped) {
             this.wrapped = wrapped;
             try {
                 wrapped.getPropertyMetadata().getField().setAccessible(true);

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

@@ -48,15 +48,15 @@ private <T> boolean isMapOrCollection(final Class<T> clazz) {
 
     @SuppressWarnings("unchecked")
     private <T> void setPropertyAccessor(final PropertyModelBuilder<T> propertyModelBuilder) {
-        propertyModelBuilder.propertyAccessor(new PrivateProperyAccessor<T>(
+        propertyModelBuilder.propertyAccessor(new PrivatePropertyAccessor<T>(
                 (PropertyAccessorImpl<T>) propertyModelBuilder.getPropertyAccessor()));
     }
 
     @SuppressWarnings({"rawtypes", "unchecked"})
-    private static final class PrivateProperyAccessor<T> implements PropertyAccessor<T> {
+    private static final class PrivatePropertyAccessor<T> implements PropertyAccessor<T> {
         private final PropertyAccessorImpl<T> wrapped;
 
-        private PrivateProperyAccessor(final PropertyAccessorImpl<T> wrapped) {
+        private PrivatePropertyAccessor(final PropertyAccessorImpl<T> wrapped) {
             this.wrapped = wrapped;
         }
 

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

@@ -69,18 +69,26 @@ public final class Conventions {
      */
     public static final Convention USE_GETTERS_FOR_SETTERS = new ConventionUseGettersAsSettersImpl();
 
+
+    /**
+     * A convention that sets the IdGenerator if the id property is either a {@link org.bson.types.ObjectId} or
+     * {@link org.bson.BsonObjectId}.
+     *
+     * @since 3.10
+     */
+    public static final Convention OBJECT_ID_GENERATORS = new ConventionObjectIdGeneratorsImpl();
+
     /**
      * The default conventions list
      */
     public static final List<Convention> DEFAULT_CONVENTIONS =
-            unmodifiableList(asList(CLASS_AND_PROPERTY_CONVENTION, ANNOTATION_CONVENTION));
+            unmodifiableList(asList(CLASS_AND_PROPERTY_CONVENTION, ANNOTATION_CONVENTION, OBJECT_ID_GENERATORS));
 
     /**
      * An empty conventions list
      */
     public static final List<Convention> NO_CONVENTIONS = Collections.emptyList();
 
-
     private Conventions() {
     }
 }

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

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2008-present 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;
+
+/**
+ * Classes that implement this interface define a way to create Ids for Pojo's.
+ *
+ * @param <T> the type of the id value.
+ * @since 3.10
+ */
+public interface IdGenerator<T> {
+    /**
+     * Generates an id for a Pojo.
+     *
+     * @return the generated id value
+     */
+    T generate();
+
+    /**
+     * @return the type of the generated id.
+     */
+    Class<T> getType();
+}

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

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2008-present 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.BsonObjectId;
+import org.bson.types.ObjectId;
+
+/**
+ * The default IdGenerators
+ *
+ * @see IdGenerator
+ * @since 3.10
+ */
+public final class IdGenerators {
+
+    /**
+     * A IdGenerator for {@code ObjectId}
+     */
+    public static final IdGenerator<ObjectId> OBJECT_ID_GENERATOR = new IdGenerator<ObjectId>() {
+
+        @Override
+        public ObjectId generate() {
+            return new ObjectId();
+        }
+
+        @Override
+        public Class<ObjectId> getType() {
+            return ObjectId.class;
+        }
+    };
+
+    /**
+     * A IdGenerator for {@code BsonObjectId}
+     */
+    public static final IdGenerator<BsonObjectId> BSON_OBJECT_ID_GENERATOR = new IdGenerator<BsonObjectId>() {
+
+        @Override
+        public BsonObjectId generate() {
+            return new BsonObjectId();
+        }
+
+        @Override
+        public Class<BsonObjectId> getType() {
+            return BsonObjectId.class;
+        }
+    };
+
+    private IdGenerators(){
+    }
+}

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

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2008-present 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.codecs.configuration.CodecConfigurationException;
+
+import static java.lang.String.format;
+
+final class IdPropertyModelHolder<I> {
+    private final PropertyModel<I> propertyModel;
+    private final IdGenerator<I> idGenerator;
+
+    static <T, I> IdPropertyModelHolder<I> create(final ClassModel<T> classModel, final PropertyModel<I> idPropertyModel) {
+        return create(classModel.getType(), idPropertyModel, classModel.getIdPropertyModelHolder().getIdGenerator());
+    }
+
+    @SuppressWarnings("unchecked")
+    static <T, I, V> IdPropertyModelHolder<I> create(final Class<T> type, final PropertyModel<I> idProperty,
+                                                     final IdGenerator<V> idGenerator) {
+        if (idProperty == null && idGenerator != null) {
+            throw new CodecConfigurationException(format("Invalid IdGenerator. There is no IdProperty set for: %s", type));
+        } else if (idGenerator != null && !idProperty.getTypeData().getType().isAssignableFrom(idGenerator.getType())) {
+            throw new CodecConfigurationException(format("Invalid IdGenerator. Mismatching types, the IdProperty type is: %s but"
+                    + " the IdGenerator type is: %s", idProperty.getTypeData().getType(), idGenerator.getType()));
+        }
+        return new IdPropertyModelHolder<I>(idProperty, (IdGenerator<I>) idGenerator);
+    }
+
+    private IdPropertyModelHolder(final PropertyModel<I> propertyModel, final IdGenerator<I> idGenerator) {
+        this.propertyModel = propertyModel;
+        this.idGenerator = idGenerator;
+    }
+
+    PropertyModel<I> getPropertyModel() {
+        return propertyModel;
+    }
+
+    IdGenerator<I> getIdGenerator() {
+        return idGenerator;
+    }
+
+    @Override
+    public boolean equals(final Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+
+        IdPropertyModelHolder<?> that = (IdPropertyModelHolder<?>) o;
+
+        if (propertyModel != null ? !propertyModel.equals(that.propertyModel) : that.propertyModel != null) {
+            return false;
+        }
+        return idGenerator != null ? idGenerator.equals(that.idGenerator) : that.idGenerator == null;
+    }
+
+    @Override
+    public int hashCode() {
+        int result = propertyModel != null ? propertyModel.hashCode() : 0;
+        result = 31 * result + (idGenerator != null ? idGenerator.hashCode() : 0);
+        return result;
+    }
+}