Consider custom converters in ConversionContext before applying collection converters.

We now inspect whether custom conversions should be applied before reading a value into a Map or Collection to consider converters for Map-like and Collection-like types.

Closes #1181

Author: mp911de

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

@@ -143,7 +143,7 @@ public MappingCassandraConverter(CassandraMappingContext mappingContext) {
 	 */
 	protected ConversionContext getConversionContext() {
 
-		return new ConversionContext(this::doReadRow, this::doReadTupleValue, this::doReadUdtValue,
+		return new ConversionContext(getCustomConversions(), this::doReadRow, this::doReadTupleValue, this::doReadUdtValue,
 				this::readCollectionOrArray, this::readMap, this::getPotentiallyConvertedSimpleRead);
 	}
 
@@ -1160,6 +1160,8 @@ protected <T> T potentiallyConvertSpelValue(Object object, Parameter<T, Cassandr
 	 */
 	protected static class ConversionContext {
 
+		private final org.springframework.data.convert.CustomConversions conversions;
+
 		private final ContainerValueConverter<Row> rowConverter;
 
 		private final ContainerValueConverter<TupleValue> tupleConverter;
@@ -1172,10 +1174,12 @@ protected static class ConversionContext {
 
 		private final ValueConverter<Object> elementConverter;
 
-		public ConversionContext(ContainerValueConverter<Row> rowConverter,
+		public ConversionContext(org.springframework.data.convert.CustomConversions conversions,
+				ContainerValueConverter<Row> rowConverter,
 				ContainerValueConverter<TupleValue> tupleConverter, ContainerValueConverter<UdtValue> udtConverter,
 				ContainerValueConverter<Collection<?>> collectionConverter, ContainerValueConverter<Map<?, ?>> mapConverter,
 				ValueConverter<Object> elementConverter) {
+			this.conversions = conversions;
 			this.rowConverter = rowConverter;
 			this.tupleConverter = tupleConverter;
 			this.udtConverter = udtConverter;
@@ -1196,6 +1200,10 @@ public <S extends Object> S convert(Object source, TypeInformation<? extends S>
 
 			Assert.notNull(typeHint, "TypeInformation must not be null");
 
+			if (conversions.hasCustomReadTarget(source.getClass(), typeHint.getType())) {
+				return (S) elementConverter.convert(source, typeHint);
+			}
+
 			if (source instanceof Collection) {
 
 				Class<?> rawType = typeHint.getType();

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

@@ -38,10 +38,14 @@
 import java.time.ZoneOffset;
 import java.util.*;
 
+import org.json.simple.JSONObject;
+import org.json.simple.parser.JSONParser;
+import org.json.simple.parser.ParseException;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.beans.factory.annotation.Value;
+import org.springframework.core.convert.converter.Converter;
 import org.springframework.data.annotation.Id;
 import org.springframework.data.annotation.ReadOnlyProperty;
 import org.springframework.data.annotation.Transient;
@@ -1445,4 +1449,53 @@ void readEmbeddedTypeWhenSourceDoesNotContainValues() {
 		WithNullableEmbeddedType target = mappingCassandraConverter.read(WithNullableEmbeddedType.class, source);
 		assertThat(target.nested).isNull();
 	}
+
+	@Test // DATACASS-1181
+	void shouldApplyCustomConverterToMapLikeType() {
+
+		CassandraCustomConversions conversions = new CassandraCustomConversions(
+				Arrays.asList(JsonToStringConverter.INSTANCE, StringToJsonConverter.INSTANCE));
+
+		this.mappingContext = new CassandraMappingContext();
+		this.mappingContext.setSimpleTypeHolder(conversions.getSimpleTypeHolder());
+
+		this.mappingCassandraConverter = new MappingCassandraConverter(mappingContext);
+		this.mappingCassandraConverter.setCustomConversions(conversions);
+		this.mappingCassandraConverter.afterPropertiesSet();
+
+		Row source = RowMockUtil.newRowMock(column("thejson", "{\"hello\":\"world\"}", DataTypes.TEXT));
+
+		TypeWithJsonObject target = mappingCassandraConverter.read(TypeWithJsonObject.class, source);
+		assertThat(target.theJson).isNotNull();
+		assertThat(target.theJson.get("hello")).isEqualTo("world");
+	}
+
+	static class TypeWithJsonObject {
+
+		JSONObject theJson;
+	}
+
+	enum StringToJsonConverter implements Converter<String, JSONObject> {
+		INSTANCE;
+
+		@Override
+		public JSONObject convert(String source) {
+			try {
+				return (JSONObject) new JSONParser().parse(source);
+			} catch (ParseException e) {
+				throw new RuntimeException(e);
+			}
+		}
+
+	}
+
+	enum JsonToStringConverter implements Converter<JSONObject, String> {
+		INSTANCE;
+
+		@Override
+		public String convert(JSONObject source) {
+			return source.toJSONString();
+		}
+
+	}
 }