DATAMONGO-1517 - Add support for Decimal128 BSON type.

Support Decimal128 as Mongo simple type if present. Decimal128 is stored as NumberDecimal.

class Person {

  String id;
  Decimal128 decimal128;

  Person(String id, Decimal128 decimal128) {
    this.id = id;
    this.decimal128 = decimal128;
  }
}

mongoTemplate.save(new Person("foo", new Decimal128(new BigDecimal("123.456"))));

is represented as:

{ "_id" : "foo", "decimal128" : NumberDecimal("123.456") }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/CustomConversions.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2016 the original author or authors.
+ * Copyright 2011-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -56,6 +56,7 @@ import org.springframework.util.Assert;
  * @author Oliver Gierke
  * @author Thomas Darimont
  * @author Christoph Strobl
+ * @author Mark Paluch
  */
 public class CustomConversions {
 
@@ -92,7 +93,7 @@ public class CustomConversions {
 
 		this.readingPairs = new LinkedHashSet<ConvertiblePair>();
 		this.writingPairs = new LinkedHashSet<ConvertiblePair>();
-		this.customSimpleTypes = new HashSet<Class<?>>();
+		this.customSimpleTypes = new HashSet<Class<?>>(ReflectiveSimpleTypes.getSupportedSimpleTypes());
 		this.customReadTargetTypes = new ConcurrentHashMap<ConvertiblePair, CacheValue<Class<?>>>();
 		this.customWriteTargetTypes = new ConcurrentHashMap<ConvertiblePair, CacheValue<Class<?>>>();
 		this.rawWriteTargetTypes = new ConcurrentHashMap<Class<?>, CacheValue<Class<?>>>();

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/ReflectiveSimpleTypes.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2017 the original author or authors.
+ *
+ * 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.springframework.data.mongodb.core.convert;
+
+import java.util.Collection;
+import java.util.Collections;
+
+import org.springframework.util.ClassUtils;
+
+/**
+ * {@link ReflectiveSimpleTypes} provides reflective access to MongoDB types that are not consistently available for
+ * various driver versions.
+ *
+ * @author Mark Paluch
+ * @since 1.10
+ */
+class ReflectiveSimpleTypes {
+
+	private static final boolean HAS_DECIMAL_128 = ClassUtils.isPresent("org.bson.types.Decimal128",
+			ReflectiveSimpleTypes.class.getClassLoader());
+
+	/**
+	 * Returns a {@link Collection} of simple MongoDB types (i.e. natively supported by the MongoDB driver) that are not
+	 * consistently available for various driver versions.
+	 * 
+	 * @return a {@link Collection} of simple MongoDB types.
+	 */
+	public static Collection<Class<?>> getSupportedSimpleTypes() {
+
+		if (HAS_DECIMAL_128) {
+			return Collections.<Class<?>> singleton(getDecimal128Class());
+		}
+
+		return Collections.emptySet();
+	}
+
+	private static Class<?> getDecimal128Class() {
+		return ClassUtils.resolveClassName("org.bson.types.Decimal128", ReflectiveSimpleTypes.class.getClassLoader());
+	}
+}

src/main/asciidoc/reference/mapping.adoc

@@ -126,6 +126,10 @@ In addition to these types, Spring Data MongoDB provides a set of built-in conve
 | native
 | `{"value" : { … }}`
 
+| `Decimal128`
+| native
+| `{"value" : NumberDecimal(…)}`
+
 | `AtomicInteger` +
 calling `get()` before the actual conversion
 | converter +