DATAMONGO-652 - Added support for $elemMatch and $ positional operator.

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/query/Field.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2011 the original author or authors.
+ * Copyright 2010-2013 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.
@@ -17,15 +17,25 @@ package org.springframework.data.mongodb.core.query;
 
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Map.Entry;
+
+import org.springframework.util.Assert;
 
 import com.mongodb.BasicDBObject;
 import com.mongodb.DBObject;
 
+/**
+ * @author Thomas Risberg
+ * @author Oliver Gierke
+ * @author Patryk Wasik
+ */
 public class Field {
 
-	private Map<String, Integer> criteria = new HashMap<String, Integer>();
-
-	private Map<String, Object> slices = new HashMap<String, Object>();
+	private final Map<String, Integer> criteria = new HashMap<String, Integer>();
+	private final Map<String, Object> slices = new HashMap<String, Object>();
+	private final Map<String, Criteria> elemMatchs = new HashMap<String, Criteria>();
+	private String postionKey;
+	private int positionValue;
 
 	public Field include(String key) {
 		criteria.put(key, Integer.valueOf(1));
@@ -47,14 +57,50 @@ public class Field {
 		return this;
 	}
 
+	public Field elemMatch(String key, Criteria elemMatchCriteria) {
+		elemMatchs.put(key, elemMatchCriteria);
+		return this;
+	}
+
+	/**
+	 * The array field must appear in the query. Only one positional {@code $} operator can appear in the projection and
+	 * only one array field can appear in the query.
+	 * 
+	 * @param field query array field, must not be {@literal null} or empty.
+	 * @param value
+	 * @return
+	 */
+	public Field position(String field, int value) {
+
+		Assert.hasText(field, "Field must not be null or empty!");
+
+		postionKey = field;
+		positionValue = value;
+
+		return this;
+	}
+
 	public DBObject getFieldsObject() {
+
 		DBObject dbo = new BasicDBObject();
+
 		for (String k : criteria.keySet()) {
-			dbo.put(k, (criteria.get(k)));
+			dbo.put(k, criteria.get(k));
 		}
+
 		for (String k : slices.keySet()) {
-			dbo.put(k, new BasicDBObject("$slice", (slices.get(k))));
+			dbo.put(k, new BasicDBObject("$slice", slices.get(k)));
 		}
+
+		for (Entry<String, Criteria> entry : elemMatchs.entrySet()) {
+			DBObject dbObject = new BasicDBObject("$elemMatch", entry.getValue().getCriteriaObject());
+			dbo.put(entry.getKey(), dbObject);
+		}
+
+		if (postionKey != null) {
+			dbo.put(postionKey + ".$", positionValue);
+		}
+
 		return dbo;
 	}
 }

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/query/QueryTests.java

@@ -18,6 +18,7 @@ package org.springframework.data.mongodb.core.query;
 import static org.hamcrest.CoreMatchers.*;
 import static org.junit.Assert.*;
 import static org.springframework.data.mongodb.core.query.Criteria.*;
+import static org.springframework.data.mongodb.core.query.Query.*;
 
 import org.junit.Assert;
 import org.junit.Rule;
@@ -32,6 +33,7 @@ import org.springframework.data.mongodb.InvalidMongoDbApiUsageException;
  * 
  * @author Thomas Risberg
  * @author Oliver Gierke
+ * @author Patryk Wasik
  */
 public class QueryTests {
 
@@ -104,6 +106,21 @@ public class QueryTests {
 		Assert.assertEquals(expectedFields, q.getFieldsObject().toString());
 	}
 
+	/**
+	 * @see DATAMONGO-652
+	 */
+	@Test
+	public void testQueryWithFieldsElemMatchAndPositionalOperator() {
+
+		Query query = query(where("name").gte("M").lte("T").and("age").not().gt(22));
+		query.fields().elemMatch("products", where("name").is("milk")).position("comments", 2);
+
+		String expected = "{ \"name\" : { \"$gte\" : \"M\" , \"$lte\" : \"T\"} , \"age\" : { \"$not\" : { \"$gt\" : 22}}}";
+		assertThat(query.getQueryObject().toString(), is(expected));
+		String expectedFields = "{ \"products\" : { \"$elemMatch\" : { \"name\" : \"milk\"}} , \"comments.$\" : 2}";
+		assertThat(query.getFieldsObject().toString(), is(expectedFields));
+	}
+
 	@Test
 	public void testSimpleQueryWithChainedCriteria() {
 		Query q = new Query(where("name").is("Thomas").and("age").lt(80));