Add support for $tsSecond aggregation operator.

See #4139
Original pull request: #4182.

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

@@ -833,6 +833,21 @@ public class DateOperators {
 			return TsIncrement.tsIncrement(dateReference());
 		}
 
+		/**
+		 * Creates new {@link AggregationExpression} that returns the seconds from a timestamp.
+		 *
+		 * @return new instance of {@link TsIncrement}.
+		 * @since 4.0
+		 */
+		public TsSecond tsSecond() {
+
+			if(timezone != null && !Timezone.none().equals(timezone)) {
+				throw new IllegalArgumentException("$tsSecond does not support timezones");
+			}
+
+			return TsSecond.tsSecond(dateReference());
+		}
+
 		private Object dateReference() {
 
 			if (usesFieldRef()) {
@@ -3254,6 +3269,63 @@ public class DateOperators {
 		}
 	}
 
+	/**
+	 * {@link AggregationExpression} for {@code $tsSecond}.
+	 *
+	 * @author Christoph Strobl
+	 * @since 4.0
+	 */
+	public static class TsSecond extends AbstractAggregationExpression {
+
+		private TsSecond(Object value) {
+			super(value);
+		}
+
+		/**
+		 * Creates new {@link TsSecond} that returns the incrementing ordinal from a timestamp.
+		 *
+		 * @param value must not be {@literal null}.
+		 * @return new instance of {@link TsSecond}.
+		 * @throws IllegalArgumentException if given {@literal value} is {@literal null}.
+		 */
+		public static TsSecond tsSecond(Object value) {
+
+			Assert.notNull(value, "Value must not be null");
+			return new TsSecond(value);
+		}
+
+		/**
+		 * Creates new {@link TsSecond} that returns the incrementing ordinal from a timestamp.
+		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return new instance of {@link TsSecond}.
+		 * @throws IllegalArgumentException if given {@literal fieldReference} is {@literal null}.
+		 */
+		public static TsSecond tsSecondValueOf(String fieldReference) {
+
+			Assert.notNull(fieldReference, "FieldReference must not be null");
+			return tsSecond(Fields.field(fieldReference));
+		}
+
+		/**
+		 * Creates new {@link TsSecond}.
+		 *
+		 * @param expression must not be {@literal null}.
+		 * @return new instance of {@link TsSecond}.
+		 * @throws IllegalArgumentException if given {@literal expression} is {@literal null}.
+		 */
+		public static TsSecond tsSecondValueOf(AggregationExpression expression) {
+
+			Assert.notNull(expression, "Expression must not be null");
+			return tsSecond(expression);
+		}
+
+		@Override
+		protected String getMongoMethod() {
+			return "$tsSecond";
+		}
+	}
+
 	/**
 	 * Interface defining a temporal unit for date operators.
 	 *

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/spel/MethodReferenceNode.java

@@ -192,6 +192,7 @@ public class MethodReferenceNode extends ExpressionNode {
 		map.put("isoWeek", singleArgRef().forOperator("$isoWeek"));
 		map.put("isoWeekYear", singleArgRef().forOperator("$isoWeekYear"));
 		map.put("tsIncrement", singleArgRef().forOperator("$tsIncrement"));
+		map.put("tsSecond", singleArgRef().forOperator("$tsSecond"));
 
 		// CONDITIONAL OPERATORS
 		map.put("cond", mapArgRef().forOperator("$cond") //

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

@@ -130,4 +130,18 @@ class DateOperatorsUnitTests {
 		assertThatExceptionOfType(IllegalArgumentException.class)
 				.isThrownBy(() -> DateOperators.zonedDateOf("purchaseDate", Timezone.valueOf("America/Chicago")).tsIncrement());
 	}
+
+	@Test // GH-4139
+	void rendersTsSecond() {
+
+		assertThat(DateOperators.dateOf("saleTimestamp").tsSecond().toDocument(Aggregation.DEFAULT_CONTEXT)).isEqualTo(
+				"{ $tsSecond: \"$saleTimestamp\" }");
+	}
+
+	@Test // GH-4139
+	void tsSecondErrorsOnTimezone() {
+
+		assertThatExceptionOfType(IllegalArgumentException.class)
+				.isThrownBy(() -> DateOperators.zonedDateOf("purchaseDate", Timezone.valueOf("America/Chicago")).tsSecond());
+	}
 }

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

@@ -1245,6 +1245,11 @@ public class SpelExpressionTransformerUnitTests {
 	void shouldTsIncrement() {
 		assertThat(transform("tsIncrement(saleTimestamp)")).isEqualTo("{ $tsIncrement: \"$saleTimestamp\" }");
 	}
+
+	@Test // GH-4139
+	void shouldTsSecond() {
+		assertThat(transform("tsSecond(saleTimestamp)")).isEqualTo("{ $tsSecond: \"$saleTimestamp\" }");
+	}
 	
 	private Document transform(String expression, Object... params) {
 		return (Document) transformer.transform(expression, Aggregation.DEFAULT_CONTEXT, params);