DATAMONGO-784 - Add support for comparison aggregation operators to group & project.

We now directly support comparison aggregation operators ($cmp, $eq, $gt, $gte, $lt, $lte and $ne) on both group and project stages. Further more we added $stdDevPop and $stdDevSamp support to the GroupOperationBuilder.

Author: christophstrobl

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/AggregationFunctionExpressions.java

@@ -33,7 +33,7 @@
  */
 public enum AggregationFunctionExpressions {
 
-	SIZE;
+	SIZE, CMP, EQ, GT, GTE, LT, LTE, NE;
 
 	/**
 	 * Returns an {@link AggregationExpression} build from the current {@link Enum} name and the given parameters.

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/GroupOperation.java

@@ -307,6 +307,50 @@ public GroupOperationBuilder max(AggregationExpression expr) {
 		return newBuilder(GroupOps.MAX, null, expr);
 	}
 
+	/**
+	 * Generates an {@link GroupOperationBuilder} for an {@code $stdDevPop}-expression that for the given field-reference.
+	 *
+	 * @param reference must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 1.10
+	 */
+	public GroupOperationBuilder stdDevPop(String reference) {
+		return newBuilder(GroupOps.STD_DEV_POP, reference, null);
+	}
+
+	/**
+	 * Generates an {@link GroupOperationBuilder} for an {@code $stdDevPop}-expression that for the given {@link AggregationExpression}.
+	 *
+	 * @param expr must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 1.10
+	 */
+	public GroupOperationBuilder stdDevPop(AggregationExpression expr) {
+		return newBuilder(GroupOps.STD_DEV_POP, null, expr);
+	}
+
+	/**
+	 * Generates an {@link GroupOperationBuilder} for an {@code $stdDevPop}-expression that for the given field-reference.
+	 *
+	 * @param reference must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 1.10
+	 */
+	public GroupOperationBuilder stdDevSamp(String reference) {
+		return newBuilder(GroupOps.STD_DEV_SAMP, reference, null);
+	}
+
+	/**
+	 * Generates an {@link GroupOperationBuilder} for an {@code $stdDevSamp}-expression that for the given {@link AggregationExpression}.
+	 *
+	 * @param expr must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 1.10
+	 */
+	public GroupOperationBuilder stdDevSamp(AggregationExpression expr) {
+		return newBuilder(GroupOps.STD_DEV_SAMP, null, expr);
+	}
+
 	private GroupOperationBuilder newBuilder(Keyword keyword, String reference, Object value) {
 		return new GroupOperationBuilder(this, new Operation(keyword, null, reference, value));
 	}
@@ -371,21 +415,18 @@ interface Keyword {
 
 	private static enum GroupOps implements Keyword {
 
-		SUM, LAST, FIRST, PUSH, AVG, MIN, MAX, ADD_TO_SET, COUNT;
+		SUM("$sum"), LAST("$last"), FIRST("$first"), PUSH("$push"), AVG("$avg"), MIN("$min"), MAX("$max"), ADD_TO_SET("$addToSet"), STD_DEV_POP("$stdDevPop"), STD_DEV_SAMP("$stdDevSamp");
 
-		@Override
-		public String toString() {
+		private String mongoOperator;
 
-			String[] parts = name().split("_");
-
-			StringBuilder builder = new StringBuilder();
+		GroupOps(String mongoOperator) {
+			this.mongoOperator = mongoOperator;
+		}
 
-			for (String part : parts) {
-				String lowerCase = part.toLowerCase(Locale.US);
-				builder.append(builder.length() == 0 ? lowerCase : StringUtils.capitalize(lowerCase));
-			}
 
-			return "$" + builder.toString();
+		@Override
+		public String toString() {
+			return mongoOperator;
 		}
 	}
 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/ProjectionOperation.java

@@ -616,6 +616,78 @@ public ProjectionOperationBuilder size() {
 			return project("size");
 		}
 
+		/**
+		 * Generates a {@code $cmp} expression (compare to) that compares the value of the field to a given value or field.
+		 *
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder cmp(Object compareValue) {
+			return project("cmp", compareValue);
+		}
+
+		/**
+		 * Generates a {@code $eq} expression (equal) that compares the value of the field to a given value or field.
+		 *
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder eq(Object compareValue) {
+			return project("eq", compareValue);
+		}
+
+		/**
+		 * Generates a {@code $gt} expression (greater than) that compares the value of the field to a given value or field.
+		 *
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder gt(Object compareValue) {
+			return project("gt", compareValue);
+		}
+
+		/**
+		 * Generates a {@code $gte} expression (greater than equal) that compares the value of the field to a given value or
+		 * field.
+		 *
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder gte(Object compareValue) {
+			return project("gte", compareValue);
+		}
+
+		/**
+		 * Generates a {@code $lt} expression (less than) that compares the value of the field to a given value or field.
+		 *
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder lt(Object compareValue) {
+			return project("lt", compareValue);
+		}
+
+		/**
+		 * Generates a {@code $lte} expression (less than equal) that compares the value of the field to a given value or
+		 * field.
+		 *
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder lte(Object compareValue) {
+			return project("lte", compareValue);
+		}
+
+		/**
+		 * Generates a {@code $ne} expression (not equal) that compares the value of the field to a given value or field.
+		 *
+		 * @return never {@literal null}.
+		 * @since 1.10
+		 */
+		public ProjectionOperationBuilder ne(Object compareValue) {
+			return project("ne", compareValue);
+		}
+
 		/**
 		 * Generates a {@code $slice} expression that returns a subset of the array held by the given field. <br />
 		 * If {@literal n} is positive, $slice returns up to the first n elements in the array. <br />

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2015 the original author or authors.
+ * Copyright 2013-2016 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.
@@ -19,6 +19,7 @@
 import static org.junit.Assert.*;
 import static org.springframework.data.mongodb.core.aggregation.AggregationFunctionExpressions.*;
 import static org.springframework.data.mongodb.core.aggregation.Fields.*;
+import static org.springframework.data.mongodb.test.util.IsBsonObject.*;
 
 import java.util.Arrays;
 
@@ -33,6 +34,7 @@
  * 
  * @author Oliver Gierke
  * @author Thomas Darimont
+ * @author Christoph Strobl
  */
 public class GroupOperationUnitTests {
 
@@ -204,6 +206,34 @@ public void shouldRenderSizeExpressionInGroup() {
 		assertThat(tagsCount.get("$first"), is((Object) new BasicDBObject("$size", Arrays.asList("$tags"))));
 	}
 
+	/**
+	 * @see DATAMONGO-784
+	 */
+	@Test
+	public void shouldRenderStdDevPopInGroup() {
+
+		GroupOperation groupOperation = Aggregation //
+				.group("quiz") //
+				.stdDevPop("score").as("stdDev");
+
+		assertThat(groupOperation.toDBObject(Aggregation.DEFAULT_CONTEXT),
+				isBsonObject().containing("$group.stdDev.$stdDevPop", "$score"));
+	}
+
+	/**
+	 * @see DATAMONGO-784
+	 */
+	@Test
+	public void shouldRenderStdDevSampInGroup() {
+
+		GroupOperation groupOperation = Aggregation //
+				.group() //
+				.stdDevSamp("age").as("ageStdDev");
+
+		assertThat(groupOperation.toDBObject(Aggregation.DEFAULT_CONTEXT),
+				isBsonObject().containing("$group.ageStdDev.$stdDevSamp", "$age"));
+	}
+
 	private DBObject extractDbObjectFromGroupOperation(GroupOperation groupOperation) {
 		DBObject dbObject = groupOperation.toDBObject(Aggregation.DEFAULT_CONTEXT);
 		DBObject groupClause = DBObjectTestUtils.getAsDBObject(dbObject, "$group");

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

@@ -27,6 +27,7 @@
 import org.junit.Test;
 import org.springframework.data.mongodb.core.DBObjectTestUtils;
 import org.springframework.data.mongodb.core.aggregation.ProjectionOperation.ProjectionOperationBuilder;
+import static org.springframework.data.mongodb.test.util.IsBsonObject.*;
 
 import com.mongodb.BasicDBObject;
 import com.mongodb.DBObject;
@@ -402,6 +403,92 @@ public void shouldRenderSliceWithPositionCorrectly() throws Exception {
 				is((Object) new BasicDBObject("$slice", Arrays.<Object> asList("$field", 5, 10))));
 	}
 
+	/**
+	 * @see DATAMONGO-784
+	 */
+	@Test
+	public void  shouldRenderCmpCorrectly() {
+
+		ProjectionOperation operation = Aggregation.project().and("field").cmp(10).as("cmp10");
+
+		assertThat(operation.toDBObject(Aggregation.DEFAULT_CONTEXT),
+				isBsonObject().containing("$project.cmp10.$cmp.[0]", "$field").containing("$project.cmp10.$cmp.[1]", 10));
+	}
+
+	/**
+	 * @see DATAMONGO-784
+	 */
+	@Test
+	public void  shouldRenderEqCorrectly() {
+
+		ProjectionOperation operation = Aggregation.project().and("field").eq(10).as("eq10");
+
+		assertThat(operation.toDBObject(Aggregation.DEFAULT_CONTEXT),
+				isBsonObject().containing("$project.eq10.$eq.[0]", "$field").containing("$project.eq10.$eq.[1]", 10));
+	}
+
+	/**
+	 * @see DATAMONGO-784
+	 */
+	@Test
+	public void  shouldRenderGtCorrectly() {
+
+		ProjectionOperation operation = Aggregation.project().and("field").gt(10).as("gt10");
+
+		assertThat(operation.toDBObject(Aggregation.DEFAULT_CONTEXT),
+				isBsonObject().containing("$project.gt10.$gt.[0]", "$field").containing("$project.gt10.$gt.[1]", 10));
+	}
+
+	/**
+	 * @see DATAMONGO-784
+	 */
+	@Test
+	public void  shouldRenderGteCorrectly() {
+
+		ProjectionOperation operation = Aggregation.project().and("field").gte(10).as("gte10");
+
+		assertThat(operation.toDBObject(Aggregation.DEFAULT_CONTEXT),
+				isBsonObject().containing("$project.gte10.$gte.[0]", "$field").containing("$project.gte10.$gte.[1]", 10));
+	}
+
+	/**
+	 * @see DATAMONGO-784
+	 */
+	@Test
+	public void  shouldRenderLtCorrectly() {
+
+		ProjectionOperation operation = Aggregation.project().and("field").lt(10).as("lt10");
+
+		assertThat(operation.toDBObject(Aggregation.DEFAULT_CONTEXT),
+				isBsonObject().containing("$project.lt10.$lt.[0]", "$field").containing("$project.lt10.$lt.[1]", 10));
+	}
+
+	/**
+	 * @see DATAMONGO-784
+	 */
+	@Test
+	public void  shouldRenderLteCorrectly() {
+
+		ProjectionOperation operation = Aggregation.project().and("field").lte(10).as("lte10");
+
+		assertThat(operation.toDBObject(Aggregation.DEFAULT_CONTEXT),
+				isBsonObject().containing("$project.lte10.$lte.[0]", "$field").containing("$project.lte10.$lte.[1]", 10));
+	}
+
+	/**
+	 * @see DATAMONGO-784
+	 */
+	@Test
+	public void  shouldRenderNeCorrectly() {
+
+		ProjectionOperation operation = Aggregation.project().and("field").ne(10).as("ne10");
+
+		assertThat(operation.toDBObject(Aggregation.DEFAULT_CONTEXT),
+				isBsonObject().containing("$project.ne10.$ne.[0]", "$field").containing("$project.ne10.$ne.[1]", 10));
+	}
+
+
+
 	private static DBObject exctractOperation(String field, DBObject fromProjectClause) {
 		return (DBObject) fromProjectClause.get(field);
 	}