DATAMONGO-1538 - Polishing.

Use InheritingExposedFieldsAggregationOperationContext instead of anonymous context class for condition mapping. Drop aggregation input collections before tests. Minor reformatting.

Original pull request: spring-projects#417.

Author: mp911de

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

@@ -29,7 +29,6 @@
 import org.springframework.data.mongodb.core.aggregation.AggregationExpressions.Filter.AsBuilder;
 import org.springframework.data.mongodb.core.aggregation.AggregationExpressions.Let.ExpressionVariable;
 import org.springframework.data.mongodb.core.aggregation.ExposedFields.ExposedField;
-import org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldReference;
 import org.springframework.data.mongodb.core.query.CriteriaDefinition;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
@@ -3903,31 +3902,19 @@ public static AsBuilder filter(List<?> values) {
 		 */
 		@Override
 		public Document toDocument(final AggregationOperationContext context) {
-
-			return toFilter(new ExposedFieldsAggregationOperationContext(ExposedFields.from(as), context) {
-
-				@Override
-				public FieldReference getReference(Field field) {
-
-					FieldReference ref = null;
-					try {
-						ref = context.getReference(field);
-					} catch (Exception e) {
-						// just ignore that one.
-					}
-					return ref != null ? ref : super.getReference(field);
-				}
-			});
+			return toFilter(ExposedFields.from(as), context);
 		}
 
-		private Document toFilter(AggregationOperationContext context) {
+		private Document toFilter(ExposedFields exposedFields, AggregationOperationContext context) {
 
 			Document filterExpression = new Document();
+			InheritingExposedFieldsAggregationOperationContext operationContext = new InheritingExposedFieldsAggregationOperationContext(
+					exposedFields, context);
 
 			filterExpression.putAll(context.getMappedObject(new Document("input", getMappedInput(context))));
 			filterExpression.put("as", as.getTarget());
 
-			filterExpression.putAll(context.getMappedObject(new Document("cond", getMappedCondition(context))));
+			filterExpression.putAll(context.getMappedObject(new Document("cond", getMappedCondition(operationContext))));
 
 			return new Document("$filter", filterExpression);
 		}
@@ -6017,27 +6004,14 @@ public Map andApply(final AggregationExpression expression) {
 
 		@Override
 		public Document toDocument(final AggregationOperationContext context) {
-
-			return toMap(new ExposedFieldsAggregationOperationContext(
-					ExposedFields.synthetic(Fields.fields(itemVariableName)), context) {
-
-				@Override
-				public FieldReference getReference(Field field) {
-
-					FieldReference ref = null;
-					try {
-						ref = context.getReference(field);
-					} catch (Exception e) {
-						// just ignore that one.
-					}
-					return ref != null ? ref : super.getReference(field);
-				}
-			});
+			return toMap(ExposedFields.synthetic(Fields.fields(itemVariableName)), context);
 		}
 
-		private Document toMap(AggregationOperationContext context) {
+		private Document toMap(ExposedFields exposedFields, AggregationOperationContext context) {
 
 			Document map = new Document();
+			InheritingExposedFieldsAggregationOperationContext operationContext = new InheritingExposedFieldsAggregationOperationContext(
+					exposedFields, context);
 
 			Document input;
 			if (sourceArray instanceof Field) {
@@ -6048,7 +6022,8 @@ private Document toMap(AggregationOperationContext context) {
 
 			map.putAll(context.getMappedObject(input));
 			map.put("as", itemVariableName);
-			map.put("in", functionToApply.toDocument(new NestedDelegatingExpressionAggregationOperationContext(context)));
+			map.put("in",
+					functionToApply.toDocument(new NestedDelegatingExpressionAggregationOperationContext(operationContext)));
 
 			return new Document("$map", map);
 		}
@@ -6790,22 +6765,7 @@ public interface LetBuilder {
 
 		@Override
 		public Document toDocument(final AggregationOperationContext context) {
-
-			return toLet(new ExposedFieldsAggregationOperationContext(
-					ExposedFields.synthetic(Fields.fields(getVariableNames())), context) {
-
-				@Override
-				public FieldReference getReference(Field field) {
-
-					FieldReference ref = null;
-					try {
-						ref = context.getReference(field);
-					} catch (Exception e) {
-						// just ignore that one.
-					}
-					return ref != null ? ref : super.getReference(field);
-				}
-			});
+			return toLet(ExposedFields.synthetic(Fields.fields(getVariableNames())), context);
 		}
 
 		private String[] getVariableNames() {
@@ -6814,20 +6774,24 @@ private String[] getVariableNames() {
 			for (int i = 0; i < this.vars.size(); i++) {
 				varNames[i] = this.vars.get(i).variableName;
 			}
+
 			return varNames;
 		}
 
-		private Document toLet(AggregationOperationContext context) {
+		private Document toLet(ExposedFields exposedFields, AggregationOperationContext context) {
 
 			Document letExpression = new Document();
 
 			Document mappedVars = new Document();
+			InheritingExposedFieldsAggregationOperationContext operationContext = new InheritingExposedFieldsAggregationOperationContext(
+					exposedFields, context);
+
 			for (ExpressionVariable var : this.vars) {
 				mappedVars.putAll(getMappedVariable(var, context));
 			}
 
 			letExpression.put("vars", mappedVars);
-			letExpression.put("in", getMappedIn(context));
+			letExpression.put("in", getMappedIn(operationContext));
 
 			return new Document("$let", letExpression);
 		}

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

@@ -13,17 +13,16 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
 package org.springframework.data.mongodb.core.aggregation;
 
 import org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldReference;
-import org.springframework.util.Assert;
 
 /**
  * {@link ExposedFieldsAggregationOperationContext} that inherits fields from its parent
  * {@link AggregationOperationContext}.
  *
  * @author Mark Paluch
+ * @since 1.9
  */
 class InheritingExposedFieldsAggregationOperationContext extends ExposedFieldsAggregationOperationContext {
 
@@ -40,7 +39,7 @@ public InheritingExposedFieldsAggregationOperationContext(ExposedFields exposedF
 			AggregationOperationContext previousContext) {
 
 		super(exposedFields, previousContext);
-		Assert.notNull(previousContext, "PreviousContext must not be null!");
+
 		this.previousContext = previousContext;
 	}
 

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

@@ -138,6 +138,8 @@ private void cleanDb() {
 		mongoTemplate.dropCollection(MeterData.class);
 		mongoTemplate.dropCollection(LineItem.class);
 		mongoTemplate.dropCollection(InventoryItem.class);
+		mongoTemplate.dropCollection(Sales.class);
+		mongoTemplate.dropCollection(Sales2.class);
 	}
 
 	/**