DATAMONGO-1133 - Field aliasing is not honored in Aggregation operations.

Added some test to show that we now use the field name for resolving the property path. Previously we used the field target name as is which didn’t honour field aliases.

Author: Thomas Darimont

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/AggregationTests.java

@@ -125,6 +125,7 @@ private void cleanDb() {
 		mongoTemplate.dropCollection(Person.class);
 		mongoTemplate.dropCollection(Reservation.class);
 		mongoTemplate.dropCollection(Venue.class);
+		mongoTemplate.dropCollection(MeterData.class);
 	}
 
 	/**
@@ -1044,6 +1045,30 @@ public void shouldSupportGeoNearQueriesForAggregationWithDistanceField() {
 		assertThat((Double) firstResult.get("distance"), closeTo(117.620092203928, 0.00001));
 	}
 
+	/**
+	 * @see DATAMONGO-1133
+	 */
+	@Test
+	public void shouldHonorFieldAliasesForFieldReferences() {
+
+		mongoTemplate.insert(new MeterData("m1", "counter1", 42));
+		mongoTemplate.insert(new MeterData("m1", "counter1", 13));
+		mongoTemplate.insert(new MeterData("m1", "counter1", 45));
+
+		TypedAggregation<MeterData> agg = newAggregation(MeterData.class, //
+				match(where("resourceId").is("m1")), //
+				group("counterName").sum("counterVolume").as("totalValue") //
+		);
+
+		AggregationResults<DBObject> results = mongoTemplate.aggregate(agg, DBObject.class);
+
+		assertThat(results.getMappedResults(), hasSize(1));
+		DBObject result = results.getMappedResults().get(0);
+
+		assertThat(result.get("_id"), is(equalTo((Object) "counter1")));
+		assertThat(result.get("totalValue"), is(equalTo((Object) 42.0)));
+	}
+
 	private void assertLikeStats(LikeStats like, String id, long count) {
 
 		assertThat(like, is(notNullValue()));

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/MeterData.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2015 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.aggregation;
+
+import org.springframework.data.annotation.Id;
+import org.springframework.data.mongodb.core.mapping.Field;
+
+/**
+ * @author Thomas Darimont
+ */
+public class MeterData {
+
+	@Id String resourceId;
+	@Field("counter_name") String counterName;
+	double counterVolume;
+
+	public MeterData() {}
+
+	public MeterData(String resourceId, String counterName, double counterVolume) {
+
+		this.resourceId = resourceId;
+		this.counterName = counterName;
+		this.counterVolume = counterVolume;
+	}
+}

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/TypeBasedAggregationOperationContextUnitTests.java

@@ -169,6 +169,24 @@ public void rendersAggregationOptionsInTypedAggregationContextCorrectly() {
 		assertThat(dbo.get("cursor"), is((Object) new BasicDBObject("foo", 1)));
 	}
 
+	/**
+	 * @see DATAMONGO-1133
+	 */
+	@Test
+	public void shouldHonorAliasedFieldsInGroupExpressions() {
+
+		TypeBasedAggregationOperationContext context = getContext(MeterData.class);
+		TypedAggregation<MeterData> agg = newAggregation(MeterData.class,
+				group("counterName").sum("counterVolume").as("totalCounterVolume"));
+
+		DBObject dbo = agg.toDbObject("meterData", context);
+		DBObject group = getPipelineElementFromAggregationAt(dbo, 0);
+
+		DBObject definition = (DBObject) group.get("$group");
+
+		assertThat(definition.get("_id"), is(equalTo((Object) "$counter_name")));
+	}
+
 	@Document(collection = "person")
 	public static class FooPerson {