diff --git a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/ArithmeticOperators.java b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/ArithmeticOperators.java
index 10785623e..40f28d94c 100644
--- a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/ArithmeticOperators.java
+++ b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/ArithmeticOperators.java
@@ -511,6 +511,27 @@ public class ArithmeticOperators {
: AccumulatorOperators.StdDevSamp.stdDevSampOf(expression);
}
+ /**
+ * Creates new {@link AggregationExpression} that rounds a number to a whole integer or to a specified decimal
+ * place.
+ *
+ * @return new instance of {@link Round}.
+ * @since 3.0
+ */
+ public Round round() {
+ return usesFieldRef() ? Round.roundValueOf(fieldReference) : Round.roundValueOf(expression);
+ }
+
+ /**
+ * Creates new {@link AggregationExpression} that rounds a number to a specified decimal place.
+ *
+ * @return new instance of {@link Round}.
+ * @since 3.0
+ */
+ public Round roundToPlace(int place) {
+ return round().place(place);
+ }
+
private boolean usesFieldRef() {
return fieldReference != null;
}
@@ -1422,4 +1443,100 @@ public class ArithmeticOperators {
return new Trunc(value);
}
}
+
+ /**
+ * {@link Round} rounds a number to a whole integer or to a specified decimal place.
+ *
+ * - If {@link Round#place(int)} resolves to a positive integer, {@code $round} rounds to the given decimal
+ * places.
+ * - If {@link Round#place(int)} resolves to a negative integer, {@code $round} rounds to the left of the
+ * decimal.
+ * - If {@link Round#place(int)} resolves to a zero, {@code $round} rounds using the first digit to the right of the
+ * decimal.
+ *
+ *
+ * @since 3.0
+ */
+ public static class Round extends AbstractAggregationExpression {
+
+ private Round(Object value) {
+ super(value);
+ }
+
+ /**
+ * Round the value of the field that resolves to an integer, double, decimal, or long.
+ *
+ * @param fieldReference must not be {@literal null}.
+ * @return new instance of {@link Round}.
+ */
+ public static Round roundValueOf(String fieldReference) {
+
+ Assert.notNull(fieldReference, "FieldReference must not be null!");
+ return new Round(Collections.singletonList(Fields.field(fieldReference)));
+ }
+
+ /**
+ * Round the outcome of the given expression hat resolves to an integer, double, decimal, or long.
+ *
+ * @param expression must not be {@literal null}.
+ * @return new instance of {@link Round}.
+ */
+ public static Round roundValueOf(AggregationExpression expression) {
+
+ Assert.notNull(expression, "Expression must not be null!");
+ return new Round(Collections.singletonList(expression));
+ }
+
+ /**
+ * Round the given numeric (integer, double, decimal, or long) value.
+ *
+ * @param value must not be {@literal null}.
+ * @return new instance of {@link Round}.
+ */
+ public static Round round(Number value) {
+
+ Assert.notNull(value, "Value must not be null!");
+ return new Round(Collections.singletonList(value));
+ }
+
+ /**
+ * The place to round to. Can be between -20 and 100, exclusive.
+ *
+ * @param place
+ * @return new instance of {@link Round}.
+ */
+ public Round place(int place) {
+ return new Round(append(place));
+ }
+
+ /**
+ * The place to round to defined by an expression that resolves to an integer between -20 and 100, exclusive.
+ *
+ * @param expression must not be {@literal null}.
+ * @return new instance of {@link Round}.
+ */
+ public Round placeOf(AggregationExpression expression) {
+
+ Assert.notNull(expression, "Expression must not be null!");
+ return new Round(append(expression));
+ }
+
+ /**
+ * The place to round to defined by via a field reference that resolves to an integer between -20 and 100,
+ * exclusive.
+ *
+ * @param fieldReference must not be {@literal null}.
+ * @return new instance of {@link Round}.
+ */
+ public Round placeOf(String fieldReference) {
+
+ Assert.notNull(fieldReference, "fieldReference must not be null!");
+ return new Round(append(Fields.field(fieldReference)));
+ }
+
+ @Override
+ protected String getMongoMethod() {
+ return "$round";
+ }
+ }
}
diff --git a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/spel/MethodReferenceNode.java b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/spel/MethodReferenceNode.java
index fd00c39a4..dcc351fa0 100644
--- a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/spel/MethodReferenceNode.java
+++ b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/spel/MethodReferenceNode.java
@@ -84,6 +84,7 @@ public class MethodReferenceNode extends ExpressionNode {
map.put("sqrt", singleArgRef().forOperator("$sqrt"));
map.put("subtract", arrayArgRef().forOperator("$subtract"));
map.put("trunc", singleArgRef().forOperator("$trunc"));
+ map.put("round", arrayArgRef().forOperator("$round"));
// STRING OPERATORS
map.put("concat", arrayArgRef().forOperator("$concat"));
diff --git a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/ArithmeticOperatorsUnitTests.java b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/ArithmeticOperatorsUnitTests.java
new file mode 100644
index 000000000..4fd7a226a
--- /dev/null
+++ b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/ArithmeticOperatorsUnitTests.java
@@ -0,0 +1,61 @@
+/*
+ * Copyright 2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core.aggregation;
+
+import static org.assertj.core.api.Assertions.*;
+import static org.springframework.data.mongodb.core.aggregation.ArithmeticOperators.*;
+
+import java.util.Arrays;
+import java.util.Collections;
+
+import org.bson.Document;
+import org.junit.jupiter.api.Test;
+
+/**
+ * @author Christoph Strobl
+ */
+
+public class ArithmeticOperatorsUnitTests {
+
+ @Test // DATAMONGO-2370
+ void roundShouldWithoutPlace() {
+
+ assertThat(valueOf("field").round().toDocument(Aggregation.DEFAULT_CONTEXT))
+ .isEqualTo(new Document("$round", Collections.singletonList("$field")));
+ }
+
+ @Test // DATAMONGO-2370
+ void roundShouldWithPlace() {
+
+ assertThat(valueOf("field").roundToPlace(3).toDocument(Aggregation.DEFAULT_CONTEXT))
+ .isEqualTo(new Document("$round", Arrays.asList("$field", Integer.valueOf(3))));
+ }
+
+ @Test // DATAMONGO-2370
+ void roundShouldWithPlaceFromField() {
+
+ assertThat(valueOf("field").round().placeOf("my-field").toDocument(Aggregation.DEFAULT_CONTEXT))
+ .isEqualTo(new Document("$round", Arrays.asList("$field", "$my-field")));
+ }
+
+ @Test // DATAMONGO-2370
+ void roundShouldWithPlaceFromExpression() {
+
+ assertThat(valueOf("field").round().placeOf((ctx -> new Document("$first", "$source")))
+ .toDocument(Aggregation.DEFAULT_CONTEXT))
+ .isEqualTo(new Document("$round", Arrays.asList("$field", new Document("$first", "$source"))));
+ }
+}
diff --git a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/SpelExpressionTransformerUnitTests.java b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/SpelExpressionTransformerUnitTests.java
index ac16820de..28053b950 100644
--- a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/SpelExpressionTransformerUnitTests.java
+++ b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/SpelExpressionTransformerUnitTests.java
@@ -23,7 +23,6 @@ import org.bson.Document;
import org.junit.Before;
import org.junit.Ignore;
import org.junit.Test;
-
import org.springframework.data.mongodb.core.Person;
/**
@@ -935,6 +934,16 @@ public class SpelExpressionTransformerUnitTests {
assertThat(transform("range(0, 10, 2)")).isEqualTo(Document.parse("{ \"$range\" : [0, 10, 2 ]}"));
}
+ @Test // DATAMONGO-2370
+ public void shouldRenderRound() {
+ assertThat(transform("round(field)")).isEqualTo(Document.parse("{ \"$round\" : [\"$field\"]}"));
+ }
+
+ @Test // DATAMONGO-2370
+ public void shouldRenderRoundWithPlace() {
+ assertThat(transform("round(field, 2)")).isEqualTo(Document.parse("{ \"$round\" : [\"$field\", 2]}"));
+ }
+
private Object transform(String expression, Object... params) {
Object result = transformer.transform(expression, Aggregation.DEFAULT_CONTEXT, params);
return result == null ? null : (!(result instanceof org.bson.Document) ? result.toString() : result);
diff --git a/src/main/asciidoc/reference/mongodb.adoc b/src/main/asciidoc/reference/mongodb.adoc
index 3eb5ec511..f4a9a1985 100644
--- a/src/main/asciidoc/reference/mongodb.adoc
+++ b/src/main/asciidoc/reference/mongodb.adoc
@@ -2516,7 +2516,7 @@ At the time of this writing, we provide support for the following Aggregation Op
| `addToSet`, `first`, `last`, `max`, `min`, `avg`, `push`, `sum`, `(*count)`, `stdDevPop`, `stdDevSamp`
| Arithmetic Aggregation Operators
-| `abs`, `add` (*via `plus`), `ceil`, `divide`, `exp`, `floor`, `ln`, `log`, `log10`, `mod`, `multiply`, `pow`, `sqrt`, `subtract` (*via `minus`), `trunc`
+| `abs`, `add` (*via `plus`), `ceil`, `divide`, `exp`, `floor`, `ln`, `log`, `log10`, `mod`, `multiply`, `pow`, `sqrt`, `subtract` (*via `minus`), `trunc`, `round`
| String Aggregation Operators
| `concat`, `substr`, `toLower`, `toUpper`, `stcasecmp`, `indexOfBytes`, `indexOfCP`, `split`, `strLenBytes`, `strLenCP`, `substrCP`, `trim`, `ltrim`, `rtim`