DATAMONGO-1540 - Polishing.

Reduce Map aggregation expression builder entrypoint. Fix JavaDoc.

Original pull request: spring-projects#420.

Author: mp911de

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

@@ -25,7 +25,6 @@
 import com.mongodb.DBObject;
 import org.bson.Document;
 import org.springframework.data.mongodb.core.aggregation.AggregationExpressions.Filter.AsBuilder;
-import org.springframework.data.mongodb.core.aggregation.AggregationExpressions.Map.ArrayOfBuilder;
 import org.springframework.data.mongodb.core.aggregation.ExposedFields.ExposedField;
 import org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldReference;
 import org.springframework.util.Assert;
@@ -1782,20 +1781,33 @@ private boolean usesFieldRef() {
 	}
 
 	/**
-	 * Gateway to {@literal Date} aggregation operations.
+	 * Gateway to {@literal variable} aggregation operations.
 	 *
 	 * @author Christoph Strobl
+	 * @author Mark Paluch
 	 */
 	class VariableOperators {
 
 		/**
 		 * Starts building new {@link Map} that applies an {@link AggregationExpression} to each item of a referenced array
 		 * and returns an array with the applied results.
 		 *
+		 * @param fieldReference must not be {@literal null}.
+		 * @return
+		 */
+		public static Map.AsBuilder mapItemsOf(String fieldReference) {
+			return Map.itemsOf(fieldReference);
+		}
+
+		/**
+		 * Starts building new {@link Map} that applies an {@link AggregationExpression} to each item of a referenced array
+		 * and returns an array with the applied results.
+		 *
+		 * @param expression must not be {@literal null}.
 		 * @return
 		 */
-		public static ArrayOfBuilder map() {
-			return Map.map();
+		public static Map.AsBuilder mapItemsOf(AggregationExpression expression) {
+			return Map.itemsOf(expression);
 		}
 	}
 
@@ -5757,51 +5769,52 @@ private Map(Object sourceArray, String itemVariableName, AggregationExpression f
 		 * Starts building new {@link Map} that applies an {@link AggregationExpression} to each item of a referenced array
 		 * and returns an array with the applied results.
 		 *
+		 * @param fieldReference must not be {@literal null}.
 		 * @return
 		 */
-		static ArrayOfBuilder map() {
+		static AsBuilder itemsOf(final String fieldReference) {
 
-			return new ArrayOfBuilder() {
+			return new AsBuilder() {
 
 				@Override
-				public AsBuilder itemsOf(final String fieldReference) {
+				public FunctionBuilder as(final String variableName) {
 
-					return new AsBuilder() {
+					return new FunctionBuilder() {
 
 						@Override
-						public FunctionBuilder as(final String variableName) {
-
-							return new FunctionBuilder() {
-
-								@Override
-								public Map andApply(final AggregationExpression expression) {
-									return new Map(Fields.field(fieldReference), variableName, expression);
-								}
-							};
+						public Map andApply(final AggregationExpression expression) {
+							return new Map(Fields.field(fieldReference), variableName, expression);
 						}
 					};
 				}
 
-				@Override
-				public AsBuilder itemsOf(final AggregationExpression source) {
+			};
+		};
 
-					return new AsBuilder() {
+		/**
+		 * Starts building new {@link Map} that applies an {@link AggregationExpression} to each item of a referenced array
+		 * and returns an array with the applied results.
+		 *
+		 * @param source must not be {@literal null}.
+		 * @return
+		 */
+		public static AsBuilder itemsOf(final AggregationExpression source) {
 
-						@Override
-						public FunctionBuilder as(final String variableName) {
+			return new AsBuilder() {
+
+				@Override
+				public FunctionBuilder as(final String variableName) {
 
-							return new FunctionBuilder() {
+					return new FunctionBuilder() {
 
-								@Override
-								public Map andApply(final AggregationExpression expression) {
-									return new Map(source, variableName, expression);
-								}
-							};
+						@Override
+						public Map andApply(final AggregationExpression expression) {
+							return new Map(source, variableName, expression);
 						}
 					};
 				}
 			};
-		};
+		}
 
 		@Override
 		public Document toDocument(final AggregationOperationContext context) {
@@ -5841,26 +5854,6 @@ private Document toMap(AggregationOperationContext context) {
 			return new Document("$map", map);
 		}
 
-		interface ArrayOfBuilder {
-
-			/**
-			 * Set the field that resolves to an array on which to apply the {@link AggregationExpression}.
-			 *
-			 * @param fieldReference must not be {@literal null}.
-			 * @return
-			 */
-			AsBuilder itemsOf(String fieldReference);
-
-			/**
-			 * Set the {@link AggregationExpression} that results in an array on which to apply the
-			 * {@link AggregationExpression}.
-			 *
-			 * @param expression must not be {@literal null}.
-			 * @return
-			 */
-			AsBuilder itemsOf(AggregationExpression expression);
-		}
-
 		interface AsBuilder {
 
 			/**

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

@@ -1674,13 +1674,13 @@ public void shouldRenderNotAggregationExpression() {
 	}
 
 	/**
-	 * @see DATAMONGO-784
+	 * @see DATAMONGO-1540
 	 */
 	@Test
 	public void shouldRenderMapAggregationExpression() {
 
 		Document agg = Aggregation.project()
-				.and(VariableOperators.map().itemsOf("quizzes").as("grade")
+				.and(VariableOperators.mapItemsOf("quizzes").as("grade")
 						.andApply(AggregationFunctionExpressions.ADD.of(field("grade"), 2)))
 				.as("adjustedGrades").toDocument(Aggregation.DEFAULT_CONTEXT);
 
@@ -1689,13 +1689,13 @@ public void shouldRenderMapAggregationExpression() {
 	}
 
 	/**
-	 * @see DATAMONGO-784
+	 * @see DATAMONGO-1540
 	 */
 	@Test
 	public void shouldRenderMapAggregationExpressionOnExpression() {
 
 		Document agg = Aggregation.project()
-				.and(VariableOperators.map().itemsOf(AggregationFunctionExpressions.SIZE.of("foo")).as("grade")
+				.and(VariableOperators.mapItemsOf(AggregationFunctionExpressions.SIZE.of("foo")).as("grade")
 						.andApply(AggregationFunctionExpressions.ADD.of(field("grade"), 2)))
 				.as("adjustedGrades").toDocument(Aggregation.DEFAULT_CONTEXT);
 

src/main/asciidoc/reference/mongodb.adoc

@@ -1702,6 +1702,10 @@ At the time of this writing we provide support for the following Aggregation Ope
 | Date Aggregation Operators
 | dayOfYear, dayOfMonth, dayOfWeek, year, month, week, hour, minute, second, millisecond, dateToString
 
+| Variable Operators
+| map
+
+
 | Conditional Aggregation Operators
 | cond, ifNull