Create a new conversion context for projection properties.

We now create a new conversion context to ensure that we use the correct property type to avoid type retention when mapping complex objects within a projection.

Closes #1240

Author: mp911de

spring-data-cassandra/src/main/java/org/springframework/data/cassandra/core/convert/MappingCassandraConverter.java

@@ -27,6 +27,7 @@
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.BeanClassLoaderAware;
 import org.springframework.context.ApplicationContext;
@@ -39,7 +40,16 @@
 import org.springframework.data.cassandra.core.mapping.*;
 import org.springframework.data.cassandra.core.mapping.Embedded.OnEmpty;
 import org.springframework.data.convert.CustomConversions;
-import org.springframework.data.mapping.*;
+import org.springframework.data.mapping.AccessOptions;
+import org.springframework.data.mapping.InstanceCreatorMetadata;
+import org.springframework.data.mapping.MappingException;
+import org.springframework.data.mapping.Parameter;
+import org.springframework.data.mapping.PersistentEntity;
+import org.springframework.data.mapping.PersistentProperty;
+import org.springframework.data.mapping.PersistentPropertyAccessor;
+import org.springframework.data.mapping.PersistentPropertyPath;
+import org.springframework.data.mapping.PersistentPropertyPathAccessor;
+import org.springframework.data.mapping.PreferredConstructor;
 import org.springframework.data.mapping.context.MappingContext;
 import org.springframework.data.mapping.model.ConvertingPropertyAccessor;
 import org.springframework.data.mapping.model.DefaultSpELExpressionEvaluator;
@@ -1022,8 +1032,7 @@ protected Object getPotentiallyConvertedSimpleRead(Object value, TypeInformation
 	@SuppressWarnings({ "rawtypes", "unchecked" })
 	private Object getPotentiallyConvertedSimpleRead(@Nullable Object value, @Nullable Class<?> target) {
 
-		if (value == null || target == null
-				|| ClassUtils.isAssignableValue(target, value)) {
+		if (value == null || target == null || ClassUtils.isAssignableValue(target, value)) {
 			return value;
 		}
 
@@ -1537,7 +1546,9 @@ ConversionContext forProperty(String name) {
 
 			EntityProjection<?, ?> property = projection.findProperty(name);
 			if (property == null) {
-				return super.forProperty(name);
+				return new ConversionContext(conversions, MappingCassandraConverter.this::doReadRow,
+						MappingCassandraConverter.this::doReadTupleValue, MappingCassandraConverter.this::doReadUdtValue,
+						collectionConverter, mapConverter, elementConverter);
 			}
 
 			return new ProjectingConversionContext(conversions, rowConverter, tupleConverter, udtConverter,

spring-data-cassandra/src/test/java/org/springframework/data/cassandra/core/convert/MappingCassandraConverterUnitTests.java

@@ -59,13 +59,15 @@
 import org.springframework.data.cassandra.domain.TypeWithMapId;
 import org.springframework.data.cassandra.domain.User;
 import org.springframework.data.cassandra.domain.UserToken;
+import org.springframework.data.cassandra.support.UserDefinedTypeBuilder;
 import org.springframework.data.cassandra.test.util.RowMockUtil;
 import org.springframework.data.projection.EntityProjection;
 import org.springframework.data.projection.EntityProjectionIntrospector;
 import org.springframework.data.projection.SpelAwareProxyProjectionFactory;
 
 import com.datastax.oss.driver.api.core.CqlIdentifier;
 import com.datastax.oss.driver.api.core.cql.Row;
+import com.datastax.oss.driver.api.core.data.UdtValue;
 import com.datastax.oss.driver.api.core.type.DataTypes;
 import com.datastax.oss.driver.internal.core.data.DefaultTupleValue;
 import com.datastax.oss.driver.internal.core.type.DefaultTupleType;
@@ -1378,6 +1380,29 @@ void shouldApplyCustomConverterToMapLikeType() {
 		assertThat(target.theJson.get("hello")).isEqualTo("world");
 	}
 
+	@Test // GH-1240
+	void shouldReadOpenProjectionWithNestedObject() {
+
+		com.datastax.oss.driver.api.core.type.UserDefinedType authorType = UserDefinedTypeBuilder.forName("author")
+				.withField("firstName", DataTypes.TEXT).withField("lastName", DataTypes.TEXT).build();
+
+		UdtValue udtValue = authorType.newValue().setString("firstName", "Walter").setString("lastName", "White");
+
+		Row source = RowMockUtil.newRowMock(column("id", "id-1", DataTypes.TEXT), column("name", "my-book", DataTypes.INT),
+				column("author", udtValue, authorType));
+
+		EntityProjectionIntrospector introspector = EntityProjectionIntrospector.create(
+				mappingCassandraConverter.getProjectionFactory(),
+				EntityProjectionIntrospector.ProjectionPredicate.typeHierarchy()
+						.and((target, underlyingType) -> !mappingCassandraConverter.getCustomConversions().isSimpleType(target)),
+				mappingContext);
+
+		BookProjection projection = mappingCassandraConverter
+				.project(introspector.introspect(BookProjection.class, Book.class), source);
+
+		assertThat(projection.getName()).isEqualTo("my-book by Walter White");
+	}
+
 	static class TypeWithJsonObject {
 
 		JSONObject theJson;
@@ -1406,4 +1431,33 @@ public String convert(JSONObject source) {
 		}
 
 	}
+
+	interface BookProjection {
+
+		@Value("#{target.name + ' by ' + target.author.firstName + ' ' + target.author.lastName}")
+		String getName();
+	}
+
+	@Data
+	static class Book {
+
+		@Id String id;
+
+		String name;
+
+		Author author = new Author();
+
+	}
+
+	@Data
+	@UserDefinedType
+	static class Author {
+
+		@Id String id;
+
+		String firstName;
+
+		String lastName;
+
+	}
 }