GH-4139 add support for $sortArray direction sort

for simple arrays of literals, there is no field to sort on, just have to provide direction.

Signed-off-by: Nathan McDonald <[email protected]>

Author: nathanukey

Diff for: spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/ArrayOperators.java

@@ -24,6 +24,7 @@
 import org.bson.Document;
 import org.springframework.data.domain.Range;
 import org.springframework.data.domain.Sort;
+import org.springframework.data.domain.Sort.Direction;
 import org.springframework.data.mongodb.core.aggregation.ArrayOperators.Filter.AsBuilder;
 import org.springframework.data.mongodb.core.aggregation.ArrayOperators.Reduce.PropertyExpression;
 import org.springframework.data.mongodb.core.aggregation.ExposedFields.ExposedField;
@@ -336,6 +337,22 @@ public SortArray sort(Sort sort) {
 			return (usesExpression() ? SortArray.sortArrayOf(expression) : SortArray.sortArray(values)).by(sort);
 		}
 
+		/**
+		 * Creates new {@link AggregationExpression} that takes the associated array and sorts it by the given {@link Sort
+		 * order}.
+		 *
+		 * @return new instance of {@link SortArray}.
+		 * @since 4.0
+		 */
+		public SortArray sort(Direction direction) {
+
+			if (usesFieldRef()) {
+				return SortArray.sortArrayOf(fieldReference).by(direction);
+			}
+
+			return (usesExpression() ? SortArray.sortArrayOf(expression) : SortArray.sortArray(values)).by(direction);
+		}
+
 		/**
 		 * Creates new {@link AggregationExpression} that transposes an array of input arrays so that the first element of
 		 * the output array would be an array containing, the first element of the first input array, the first element of
@@ -2059,6 +2076,16 @@ public SortArray by(Sort sort) {
 			return new SortArray(append("sortBy", sort));
 		}
 
+		/**
+		 * Set the order to put elements in.
+		 *
+		 * @param direction must not be {@literal null}.
+		 * @return new instance of {@link SortArray}.
+		 */
+		public SortArray by(Direction direction) {
+			return new SortArray(append("sortBy", direction.isAscending() ? 1 : -1));
+		}
+
 		/*
 		 * (non-Javadoc)
 		 * @see org.springframework.data.mongodb.core.aggregation.AbstractAggregationExpression#getMongoMethod()

Diff for: spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/ArrayOperatorsUnitTests.java

@@ -24,6 +24,7 @@
 import org.bson.Document;
 import org.junit.jupiter.api.Test;
 import org.springframework.data.domain.Sort;
+import org.springframework.data.domain.Sort.Direction;
 import org.springframework.data.mongodb.core.aggregation.ArrayOperators.ArrayToObject;
 
 /**
@@ -179,4 +180,11 @@ void sortByWithFieldRef() {
 		assertThat(ArrayOperators.arrayOf("team").sort(Sort.by("name")).toDocument(Aggregation.DEFAULT_CONTEXT))
 				.isEqualTo("{ $sortArray: { input: \"$team\", sortBy: { name: 1 } } }");
 	}
+
+	@Test // GH-4929
+	void sortByWithDirection() {
+
+		assertThat(ArrayOperators.arrayOf(List.of("a", "b", "d", "c")).sort(Direction.DESC).toDocument(Aggregation.DEFAULT_CONTEXT))
+			.isEqualTo("{ $sortArray: { input: [\"a\", \"b\", \"d\", \"c\"], sortBy: -1 } }");
+	}
 }