DATAMONGO-1893 - Polishing.

Inherit fields from previous operation if at least one field is excluded. Extend FieldsExposingAggregationOperation to conditionally inherit fields.

Backport to Java 6 code.

Original pull request: #538.

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 the original author or authors.
+ * Copyright 2016-2018 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.
@@ -60,7 +60,7 @@ class AggregationOperationRenderer {
 				FieldsExposingAggregationOperation exposedFieldsOperation = (FieldsExposingAggregationOperation) operation;
 				ExposedFields fields = exposedFieldsOperation.getFields();
 
-				if (operation instanceof InheritsFieldsAggregationOperation) {
+				if (operation instanceof InheritsFieldsAggregationOperation || exposedFieldsOperation.inheritsFields()) {
 					contextToUse = new InheritingExposedFieldsAggregationOperationContext(fields, contextToUse);
 				} else {
 					contextToUse = fields.exposesNoFields() ? DEFAULT_CONTEXT

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 the original author or authors.
+ * Copyright 2016-2018 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.
@@ -169,6 +169,14 @@ public abstract class BucketOperationSupport<T extends BucketOperationSupport<T,
 		return outputs.asExposedFields();
 	}
 
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.FieldsExposingAggregationOperation#inheritsFields()
+	 */
+	@Override
+	public boolean inheritsFields() {
+		return false;
+	}
+
 	/**
 	 * Implementation hook to create a new bucket operation.
 	 *

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 the original author or authors.
+ * Copyright 2016-2018 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.
@@ -62,6 +62,14 @@ public class CountOperation implements FieldsExposingAggregationOperation {
 		return ExposedFields.from(new ExposedField(fieldName, true));
 	}
 
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.FieldsExposingAggregationOperation#inheritsFields()
+	 */
+	@Override
+	public boolean inheritsFields() {
+		return false;
+	}
+
 	/**
 	 * Builder for {@link CountOperation}.
 	 *

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2017 the original author or authors.
+ * Copyright 2016-2018 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.
@@ -96,6 +96,14 @@ public class FacetOperation implements FieldsExposingAggregationOperation {
 		return facets.asExposedFields();
 	}
 
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.FieldsExposingAggregationOperation#inheritsFields()
+	 */
+	@Override
+	public boolean inheritsFields() {
+		return false;
+	}
+
 	/**
 	 * Builder for {@link FacetOperation} by adding existing and the new pipeline of {@link AggregationOperation} to the
 	 * new {@link FacetOperation}.

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2016 the original author or authors.
+ * Copyright 2013-2018 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.
@@ -34,10 +34,13 @@ public interface FieldsExposingAggregationOperation extends AggregationOperation
 	ExposedFields getFields();
 
 	/**
-	 * Marker interface for {@link AggregationOperation} that inherits fields from previous operations.
+	 * @return {@literal true} to conditionally inherit fields from previous operations.
+	 * @since 1.10.12
 	 */
-	static interface InheritsFieldsAggregationOperation extends FieldsExposingAggregationOperation {
+	boolean inheritsFields();
-
-	}
 
+	/**
+	 * Marker interface for {@link AggregationOperation} that inherits fields from previous operations.
+	 */
+	static interface InheritsFieldsAggregationOperation extends FieldsExposingAggregationOperation {}
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2017 the original author or authors.
+ * Copyright 2016-2018 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.
@@ -132,6 +132,14 @@ public class GraphLookupOperation implements InheritsFieldsAggregationOperation
 		return ExposedFields.from(new ExposedField(as, true));
 	}
 
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.FieldsExposingAggregationOperation#inheritsFields()
+	 */
+	@Override
+	public boolean inheritsFields() {
+		return true;
+	}
+
 	/**
 	 * @author Mark Paluch
 	 */

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2017 the original author or authors.
+ * Copyright 2013-2018 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.
@@ -395,6 +395,14 @@ public class GroupOperation implements FieldsExposingAggregationOperation {
 		return fields;
 	}
 
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.FieldsExposingAggregationOperation#inheritsFields()
+	 */
+	@Override
+	public boolean inheritsFields() {
+		return false;
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2017 the original author or authors.
+ * Copyright 2016-2018 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.
@@ -73,6 +73,14 @@ public class LookupOperation implements FieldsExposingAggregationOperation, Inhe
 		return ExposedFields.from(as);
 	}
 
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.FieldsExposingAggregationOperation#inheritsFields()
+	 */
+	@Override
+	public boolean inheritsFields() {
+		return true;
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2017 the original author or authors.
+ * Copyright 2013-2018 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.
@@ -47,13 +47,12 @@ import com.mongodb.DBObject;
  * @author Christoph Strobl
  * @author Mark Paluch
  * @since 1.3
- * @see <a href="https://docs.mongodb.com/manual/reference/operator/aggregation/project/">MongoDB Aggregation Framework: $project</a>
+ * @see <a href="https://docs.mongodb.com/manual/reference/operator/aggregation/project/">MongoDB Aggregation Framework:
+ *      $project</a>
  */
 public class ProjectionOperation implements FieldsExposingAggregationOperation {
 
 	private static final List<Projection> NONE = Collections.emptyList();
-	private static final String EXCLUSION_ERROR = "Exclusion of field %s not allowed. Projections by the mongodb "
-			+ "aggregation framework only support the exclusion of the %s field!";
 
 	private final List<Projection> projections;
 
@@ -183,6 +182,25 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 		return fields;
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.FieldsExposingAggregationOperation#inheritsFields()
+	 */
+	@Override
+	public boolean inheritsFields() {
+
+		for (Projection projection : projections) {
+			if (projection instanceof FieldProjection) {
+
+				if (((FieldProjection) projection).isExcluded()) {
+					return true;
+				}
+			}
+		}
+
+		return false;
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
@@ -1332,6 +1350,13 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 				return projections;
 			}
 
+			/**
+			 * @return {@literal true} if this field is excluded.
+			 */
+			public boolean isExcluded() {
+				return Boolean.FALSE.equals(value);
+			}
+
 			/*
 			 * (non-Javadoc)
 			 * @see org.springframework.data.mongodb.core.aggregation.ProjectionOperation.Projection#toDBObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
@@ -1639,7 +1664,7 @@ public class ProjectionOperation implements FieldsExposingAggregationOperation {
 	/**
 	 * @author Thomas Darimont
 	 */
-	static class ExpressionProjection extends Projection {
+	static class ExpressionProjection extends ProjectionOperation.Projection {
 
 		private final AggregationExpression expression;
 		private final Field field;

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2017 the original author or authors.
+ * Copyright 2016-2018 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.
@@ -95,6 +95,14 @@ public class ReplaceRootOperation implements FieldsExposingAggregationOperation
 		return ExposedFields.from();
 	}
 
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.FieldsExposingAggregationOperation#inheritsFields()
+	 */
+	@Override
+	public boolean inheritsFields() {
+		return false;
+	}
+
 	/**
 	 * Builder for {@link ReplaceRootOperation}.
 	 *

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

@@ -117,6 +117,14 @@ public class UnwindOperation
 		return arrayIndex != null ? ExposedFields.from(arrayIndex) : ExposedFields.from();
 	}
 
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.FieldsExposingAggregationOperation#inheritsFields()
+	 */
+	@Override
+	public boolean inheritsFields() {
+		return true;
+	}
+
 	/**
 	 * Get a builder that allows creation of {@link LookupOperation}.
 	 *

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2017 the original author or authors.
+ * Copyright 2013-2018 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.
@@ -211,9 +211,19 @@ public class ProjectionOperationUnitTests {
 	public void excludeShouldAllowExclusionOfFieldsOtherThanUnderscoreId/* since MongoDB 3.4 */() {
 
 		ProjectionOperation projectionOp = new ProjectionOperation().andExclude("foo");
-		Document document = projectionOp.toDocument(Aggregation.DEFAULT_CONTEXT);
+		DBObject document = projectionOp.toDBObject(Aggregation.DEFAULT_CONTEXT);
-		Document projectClause = DocumentTestUtils.getAsDocument(document, PROJECT);
+		DBObject projectClause = DBObjectTestUtils.getAsDBObject(document, PROJECT);
-		assertThat((Integer) projectClause.get("foo")).isEqualTo(0);
+
+		assertThat(projectionOp.inheritsFields(), is(true));
+		assertThat((Integer) projectClause.get("foo"), is(0));
+	}
+
+	@Test // DATAMONGO-1893
+	public void includeShouldNotInheritFields() {
+
+		ProjectionOperation projectionOp = new ProjectionOperation().andInclude("foo");
+
+		assertThat(projectionOp.inheritsFields(), is(false));
 	}
 
 	@Test // DATAMONGO-758
@@ -1548,8 +1558,7 @@ public class ProjectionOperationUnitTests {
 						.andApply(AggregationFunctionExpressions.MULTIPLY.of(Fields.field("total"), Fields.field("discounted")))) //
 				.as("finalTotal").toDBObject(Aggregation.DEFAULT_CONTEXT);
 
-		assertThat(agg,
+		assertThat(agg, is(JSON.parse("{ $project:{  \"finalTotal\" : { \"$let\": {" + //
-				is(JSON.parse("{ $project:{  \"finalTotal\" : { \"$let\": {" + //
 				"\"vars\": {" + //
 				"\"total\": { \"$add\": [ \"$price\", \"$tax\" ] }," + //
 				"\"discounted\": { \"$cond\": { \"if\": \"$applyDiscount\", \"then\": 0.9, \"else\": 1.0 } }" + //
@@ -1572,8 +1581,7 @@ public class ProjectionOperationUnitTests {
 						AggregationFunctionExpressions.MULTIPLY.of(Fields.field("total"), Fields.field("discounted")))
 				.as("finalTotal").toDBObject(Aggregation.DEFAULT_CONTEXT);
 
-		assertThat(agg,
+		assertThat(agg, is(JSON.parse("{ $project:{ \"finalTotal\" : { \"$let\": {" + //
-				is(JSON.parse("{ $project:{ \"finalTotal\" : { \"$let\": {" + //
 				"\"vars\": {" + //
 				"\"total\": { \"$add\": [ \"$price\", \"$tax\" ] }," + //
 				"\"discounted\": { \"$cond\": { \"if\": \"$applyDiscount\", \"then\": 0.9, \"else\": 1.0 } }" + //

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2017 the original author or authors.
+ * Copyright 2013-2018 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.
@@ -22,6 +22,8 @@ import static org.springframework.data.mongodb.core.aggregation.Aggregation.*;
 import static org.springframework.data.mongodb.core.aggregation.Fields.*;
 import static org.springframework.data.mongodb.test.util.IsBsonObject.*;
 
+import lombok.AllArgsConstructor;
+
 import java.util.Arrays;
 import java.util.List;
 
@@ -34,7 +36,7 @@ import org.mockito.runners.MockitoJUnitRunner;
 import org.springframework.core.convert.converter.Converter;
 import org.springframework.core.convert.support.GenericConversionService;
 import org.springframework.data.annotation.Id;
-import org.springframework.data.annotation.PersistenceConstructor;
+import org.springframework.data.domain.Sort;
 import org.springframework.data.domain.Sort.Direction;
 import org.springframework.data.mapping.model.MappingException;
 import org.springframework.data.mongodb.core.aggregation.ExposedFields.DirectFieldReference;
@@ -196,6 +198,20 @@ public class TypeBasedAggregationOperationContextUnitTests {
 						.containing("age", "$age.value"));
 	}
 
+	@Test // DATAMONGO-1893
+	public void considersIncludedFieldsFromSingleExclusionsCorrectly() {
+
+		AggregationOperationContext context = getContext(FooPerson.class);
+		TypedAggregation<FooPerson> agg = newAggregation(FooPerson.class, project() //
+				.andExclude("name"), sort(new Sort("age.value", "lastName")));
+
+		DBObject dbo = agg.toDbObject("person", context);
+
+		DBObject sort = getPipelineElementFromAggregationAt(dbo, 1);
+		assertThat(getAsDBObject(sort, "$sort"),
+				is(equalTo((DBObject) new BasicDBObject("age.value", 1).append("last_name", 1))));
+	}
+
 	@Test // DATAMONGO-1133
 	public void shouldHonorAliasedFieldsInGroupExpressions() {
 
@@ -352,18 +368,13 @@ public class TypeBasedAggregationOperationContextUnitTests {
 	}
 
 	@Document(collection = "person")
+	@AllArgsConstructor
 	public static class FooPerson {
 
 		final ObjectId id;
 		final String name;
+		@org.springframework.data.mongodb.core.mapping.Field("last_name") final String lastName;
 		final Age age;
-
-		@PersistenceConstructor
-		FooPerson(ObjectId id, String name, Age age) {
-			this.id = id;
-			this.name = name;
-			this.age = age;
-		}
 	}
 
 	public static class Age {